Android 广播实现原理解析_android 广播userid的作用详解

Android 广播实现原理解析

前言

Android四大组件中的BroadcastReceiver，在我们实际工作中被频繁的使用，我们可以利用系统的开机广播，网络状态改变的广播等等实现我们的业务逻辑，也可以通过广播实现跨进程间的通信（实际上是利用binder机制）。那么广播的原理呢？是不是值得我们去深入学习一下呢。广播，简单来说分为动态注册和静态注册两种，本文将着重讲解动态注册，静态注册将与packageManagerService一起分析。注册，字面意思就是，对与我需要收到的广播报备一下，告诉系统我想要接收这个广播。这么看来，它的报备过程肯定是把相关信息保存起来嘛，有了广播后进行匹配筛选，谁要发给谁嘛。好，解析结束，下课。哈哈，开个玩笑咱们下面一步一步的开始记录。

客户端的注册

首先，我们写一个demo，对于动态注册一个广播。

   @Override
    protected void onStart() {
        super.onStart();
        IntentFilter filter = new IntentFilter();
        filter.addAction("come.letv.gaomh");
        gaomhReceiver = new GaomhReceiver();
        this.registerReceiver(gaomhReceiver,filter);
    }

    public class GaomhReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {

        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(gaomhReceiver);
    }
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注意，为了防止引起内存泄露问题，在onDestroy()中需要解除注册。动态注册的广播当进程被杀死后，又不能帮你重新拉起进程，你要是不取消注册，除了坏处，一点好处没有。
这样我们，进注册了一个广播，接下来我们看一下，它究竟注册到了什么地方。
frameworks/base/core/java/android/content/ContextWrapper.java

 @Override
    public Intent registerReceiver(
        BroadcastReceiver receiver, IntentFilter filter) {
        return mBase.registerReceiver(receiver, filter);
    }
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frameworks/base/core/java/android/app/ContextImpl.java

    @Override
    public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter) {
        return registerReceiver(receiver, filter, null, null);
    }

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 @Override
    public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter,
            String broadcastPermission, Handler scheduler) {
        return registerReceiverInternal(receiver, getUserId(),
                filter, broadcastPermission, scheduler, getOuterContext(), 0);
    }
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    private Intent registerReceiverInternal(BroadcastReceiver receiver, int userId,
            IntentFilter filter, String broadcastPermission,
            Handler scheduler, Context context, int flags) {
        IIntentReceiver rd = null;
        if (receiver != null) {
            if (mPackageInfo != null && context != null) {
                if (scheduler == null) {
                    scheduler = mMainThread.getHandler();
                }
                rd = mPackageInfo.getReceiverDispatcher(
                    receiver, context, scheduler,
                    mMainThread.getInstrumentation(), true);
            } else {
                if (scheduler == null) {
                    scheduler = mMainThread.getHandler();
                }
                rd = new LoadedApk.ReceiverDispatcher(
                        receiver, context, scheduler, null, true).getIIntentReceiver();
            }
        }
        try {
            final Intent intent = ActivityManager.getService().registerReceiver(
                    mMainThread.getApplicationThread(), mBasePackageName, rd, filter,
                    broadcastPermission, userId, flags);
            if (intent != null) {
                intent.setExtrasClassLoader(getClassLoader());
                intent.prepareToEnterProcess();
            }
            return intent;
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }
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反正是一顿调用最后来到了registerReceiverInternal()这个方法。我们很清楚的看到啊activityManager.getService().registerReceiver(),这个方法马上就要调到ActivityManagerService（之后一律写成AMS）了，那不就注册成功了？等等，好像有点不对，过去倒是过去了，咋回来啊，肉包子打狗，一去不回了。
我们发现在跑到AMS之前，还有点东西IIntentReceiver rd ，我合理猜测，这个rd会不会就是广播回来的桥梁呢？
IIntentReceiver是什么？
这里的ReceiverDispatcher又是什么呢？
它是LoadedApk中的一个内部类，保存了这个receiver的信息，用于在广播派发到本进程的时候执行，上面这方法最重要的是getIIntentReceiver，这个就非常重要了，它是一个Binder对象，说在广播注册的时候将这个binder对象传递到了AMS，然后当广播派发到本进程的时候，通过这个binder对象再会调回来，它在ReceiverDispatcher创建的时候创建。（参考资料里的文章copy的，感觉总结的很到位。）

public IIntentReceiver getReceiverDispatcher(BroadcastReceiver r,
            Context context, Handler handler,
            Instrumentation instrumentation, boolean registered) {
        synchronized (mReceivers) {
            LoadedApk.ReceiverDispatcher rd = null;
            ArrayMap<BroadcastReceiver, LoadedApk.ReceiverDispatcher> map = null;
            if (registered) {
                map = mReceivers.get(context);
                if (map != null) {
                    rd = map.get(r);
                }
            }
            if (rd == null) {
                rd = new ReceiverDispatcher(r, context, handler,
                        instrumentation, registered);
                if (registered) {
                    if (map == null) {
                        map = new ArrayMap<BroadcastReceiver, LoadedApk.ReceiverDispatcher>();
                        mReceivers.put(context, map);
                    }
                    map.put(r, rd);
                }
            } else {
                rd.validate(context, handler);
            }
            rd.mForgotten = false;
            return rd.getIIntentReceiver();
        }
    }
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 ReceiverDispatcher(BroadcastReceiver receiver, Context context,
                Handler activityThread, Instrumentation instrumentation,
                boolean registered) {
            if (activityThread == null) {
                throw new NullPointerException("Handler must not be null");
            }

            mIIntentReceiver = new InnerReceiver(this, !registered);
            mReceiver = receiver;
            mContext = context;
            mActivityThread = activityThread;
            mInstrumentation = instrumentation;
            mRegistered = registered;
            mLocation = new IntentReceiverLeaked(null);
            mLocation.fillInStackTrace();
        }
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ReceiverDispatcher 中的

  public void performReceive(Intent intent, int resultCode, String data,
                Bundle extras, boolean ordered, boolean sticky, int sendingUser) {
            if (ActivityThread.DEBUG_BROADCAST) {
                int seq = intent.getIntExtra("seq", -1);
                Slog.i(ActivityThread.TAG, "Enqueueing broadcast " + intent.getAction() + " seq=" + seq
                        + " to " + mReceiver);
            }
            Args args = new Args(intent, resultCode, data, extras, ordered,
                    sticky, sendingUser);
            if (!mActivityThread.post(args)) {
                if (mRegistered && ordered) {
                    IActivityManager mgr = ActivityManagerNative.getDefault();
                    if (ActivityThread.DEBUG_BROADCAST) Slog.i(ActivityThread.TAG,
                            "Finishing sync broadcast to " + mReceiver);
                    args.sendFinished(mgr);
                }
            }
        }
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这里就是广播真正派发到本进程的时候从systemserver binder call过来执行的。
到这里我们就把注册的去处以及回来的路都铺垫好了，下面我们一起走到AMS中一探究竟。

AMS对于动态注册广播的处理

这也太长了吧，我其实一直在想，之前到底是谁和我说的一个方法最好不要超过多少多少行，出来一下，谢谢。
嫌太长的兄弟再往下翻翻，我会把步骤提取出来。

    public Intent registerReceiver(IApplicationThread caller, String callerPackage,
            IIntentReceiver receiver, IntentFilter filter, String permission, int userId) {
        enforceNotIsolatedCaller("registerReceiver");
        ArrayList<Intent> stickyIntents = null;
        ProcessRecord callerApp = null;
        int callingUid;
        int callingPid;
        synchronized(this) {
            if (caller != null) {
                callerApp = getRecordForAppLocked(caller);
                if (callerApp == null) {
                    throw new SecurityException(
                            "Unable to find app for caller " + caller
                            + " (pid=" + Binder.getCallingPid()
                            + ") when registering receiver " + receiver);
                }
                if (callerApp.info.uid != Process.SYSTEM_UID &&
                        !callerApp.pkgList.containsKey(callerPackage) &&
                        !"android".equals(callerPackage)) {
                    throw new SecurityException("Given caller package " + callerPackage
                            + " is not running in process " + callerApp);
                }
                callingUid = callerApp.info.uid;
                callingPid = callerApp.pid;
            } else {
                callerPackage = null;
                callingUid = Binder.getCallingUid();
                callingPid = Binder.getCallingPid();
            }

            userId = handleIncomingUser(callingPid, callingUid, userId,
                    true, ALLOW_FULL_ONLY, "registerReceiver", callerPackage);

            Iterator<String> actions = filter.actionsIterator();
            if (actions == null) {
                ArrayList<String> noAction = new ArrayList<String>(1);
                noAction.add(null);
                actions = noAction.iterator();
            }

            // Collect stickies of users
            int[] userIds = { UserHandle.USER_ALL, UserHandle.getUserId(callingUid) };
            while (actions.hasNext()) {
                String action = actions.next();
                for (int id : userIds) {
                    ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(id);
                    if (stickies != null) {
                        ArrayList<Intent> intents = stickies.get(action);
                        if (intents != null) {
                            if (stickyIntents == null) {
                                stickyIntents = new ArrayList<Intent>();
                            }
                            stickyIntents.addAll(intents);
                        }
                    }
                }
            }
        }

        ArrayList<Intent> allSticky = null;
        if (stickyIntents != null) {
            final ContentResolver resolver = mContext.getContentResolver();
            // Look for any matching sticky broadcasts...
            for (int i = 0, N = stickyIntents.size(); i < N; i++) {
                Intent intent = stickyIntents.get(i);
                // If intent has scheme "content", it will need to acccess
                // provider that needs to lock mProviderMap in ActivityThread
                // and also it may need to wait application response, so we
                // cannot lock ActivityManagerService here.
                if (filter.match(resolver, intent, true, TAG) >= 0) {
                    if (allSticky == null) {
                        allSticky = new ArrayList<Intent>();
                    }
                    allSticky.add(intent);
                }
            }
        }

        // The first sticky in the list is returned directly back to the client.
        Intent sticky = allSticky != null ? allSticky.get(0) : null;
        if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Register receiver " + filter + ": " + sticky);
        if (receiver == null) {
            return sticky;
        }

        synchronized (this) {
            if (callerApp != null && (callerApp.thread == null
                    || callerApp.thread.asBinder() != caller.asBinder())) {
                // Original caller already died
                return null;
            }
            ReceiverList rl = mRegisteredReceivers.get(receiver.asBinder());
            if (rl == null) {
                rl = new ReceiverList(this, callerApp, callingPid, callingUid,
                        userId, receiver);
                if (rl.app != null) {
                    rl.app.receivers.add(rl);
                } else {
                    try {
                        receiver.asBinder().linkToDeath(rl, 0);
                    } catch (RemoteException e) {
                        return sticky;
                    }
                    rl.linkedToDeath = true;
                }
                mRegisteredReceivers.put(receiver.asBinder(), rl);
            } else if (rl.uid != callingUid) {
                throw new IllegalArgumentException(
                        "Receiver requested to register for uid " + callingUid
                        + " was previously registered for uid " + rl.uid);
            } else if (rl.pid != callingPid) {
                throw new IllegalArgumentException(
                        "Receiver requested to register for pid " + callingPid
                        + " was previously registered for pid " + rl.pid);
            } else if (rl.userId != userId) {
                throw new IllegalArgumentException(
                        "Receiver requested to register for user " + userId
                        + " was previously registered for user " + rl.userId);
            }
            BroadcastFilter bf = new BroadcastFilter(filter, rl, callerPackage,
                    permission, callingUid, userId);
            rl.add(bf);
            if (!bf.debugCheck()) {
                Slog.w(TAG, "==> For Dynamic broadcast");
            }
            mReceiverResolver.addFilter(bf);

            // Enqueue broadcasts for all existing stickies that match
            // this filter.
            if (allSticky != null) {
                ArrayList receivers = new ArrayList();
                receivers.add(bf);

                final int stickyCount = allSticky.size();
                for (int i = 0; i < stickyCount; i++) {
                    Intent intent = allSticky.get(i);
                    BroadcastQueue queue = broadcastQueueForIntent(intent);
                    BroadcastRecord r = new BroadcastRecord(queue, intent, null,
                            null, -1, -1, null, null, AppOpsManager.OP_NONE, null, receivers,
                            null, 0, null, null, false, true, true, -1);
                    queue.enqueueParallelBroadcastLocked(r);
                    queue.scheduleBroadcastsLocked();
                }
            }

            return sticky;
        }
    }
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下面这些代码一句话解释：判断注册的广播，粘性广播的话加入到allSticky

 userId = handleIncomingUser(callingPid, callingUid, userId,
                    true, ALLOW_FULL_ONLY, "registerReceiver", callerPackage);

            Iterator<String> actions = filter.actionsIterator();
            if (actions == null) {
                ArrayList<String> noAction = new ArrayList<String>(1);
                noAction.add(null);
                actions = noAction.iterator();
            }

            // Collect stickies of users
            int[] userIds = { UserHandle.USER_ALL, UserHandle.getUserId(callingUid) };
            while (actions.hasNext()) {
                String action = actions.next();
                for (int id : userIds) {
                    ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(id);
                    if (stickies != null) {
                        ArrayList<Intent> intents = stickies.get(action);
                        if (intents != null) {
                            if (stickyIntents == null) {
                                stickyIntents = new ArrayList<Intent>();
                            }
                            stickyIntents.addAll(intents);
                        }
                    }
                }
            }
            ArrayList<Intent> allSticky = null;
        if (stickyIntents != null) {
            final ContentResolver resolver = mContext.getContentResolver();
            // Look for any matching sticky broadcasts...
            for (int i = 0, N = stickyIntents.size(); i < N; i++) {
                Intent intent = stickyIntents.get(i);
                // If intent has scheme "content", it will need to acccess
                // provider that needs to lock mProviderMap in ActivityThread
                // and also it may need to wait application response, so we
                // cannot lock ActivityManagerService here.
                if (filter.match(resolver, intent, true, TAG) >= 0) {
                    if (allSticky == null) {
                        allSticky = new ArrayList<Intent>();
                    }
                    allSticky.add(intent);
                }
            }
        }
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1.rl用来储存广播接受者
2.bf用来描述注册的广播接受者
3.rl.add(bf)
4. mReceiverResolver.addFilter(bf)
到这个时候，我们就完成了注册，其实就是把相关的一系列参数进行存储，我们之后就可以根据这些参数进行匹配，然后通过binder发送广播到这些已经注册的广播接收者。

 synchronized (this) {
          ...
            ReceiverList rl = mRegisteredReceivers.get(receiver.asBinder());
            if (rl == null) {
                rl = new ReceiverList(this, callerApp, callingPid, callingUid,
                        userId, receiver);
                if (rl.app != null) {
                    rl.app.receivers.add(rl);
                } 
                ...
            }
            ...
            BroadcastFilter bf = new BroadcastFilter(filter, rl, callerPackage,
                    permission, callingUid, userId);
            rl.add(bf);
            if (!bf.debugCheck()) {
                Slog.w(TAG, "==> For Dynamic broadcast");
            }
            mReceiverResolver.addFilter(bf);
            ...
            return sticky;
        }

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上面主要做了几件事情：

1.对caller的判断
2.遍历action，查询是否有匹配的sticky广播
3.将本次注册的广播放到mRegisteredReceivers中记录
4.如果是sticky广播，开始派发

广播的发送

终于注册完了，现在我们只需要安安静静的等待广播的来到。
其实广播的发送又有很多内容，有序广播，无序广播，粘性广播，静态注册的广播怎么发送，动态注册的广播怎么发送。
提一个问题：广播接收者，是动态注册的接收的快，还是静态注册的接收的快？（这个问题是我来北京的第一家公司面试我的一道面试题，我当时贼痛快的蒙了一个，结果答错了，不过最后居然还是面过了，哈哈）。
广播的发送流程，其实还是从系统去调到AMS中的broadcastIntent()方法，可以参考下上面的注册调到AMS，也可以写个demo自己跑跑断点哈，偷个懒直接从AMS开始写。

  public final int broadcastIntent(IApplicationThread caller,
            Intent intent, String resolvedType, IIntentReceiver resultTo,
            int resultCode, String resultData, Bundle map,
            String requiredPermission, int appOp, boolean serialized, boolean sticky, int userId) {
        enforceNotIsolatedCaller("broadcastIntent");
        synchronized(this) {
            intent = verifyBroadcastLocked(intent);

            final ProcessRecord callerApp = getRecordForAppLocked(caller);
            final int callingPid = Binder.getCallingPid();
            final int callingUid = Binder.getCallingUid();
            final long origId = Binder.clearCallingIdentity();
            int res = broadcastIntentLocked(callerApp,
                    callerApp != null ? callerApp.info.packageName : null,
                    intent, resolvedType, resultTo,
                    resultCode, resultData, map, requiredPermission, appOp, serialized, sticky,
                    callingPid, callingUid, userId);
            Binder.restoreCallingIdentity(origId);
            return res;
        }
    }
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此方法是对广播合法性进行检查，看方法名字就能看出来这不是verify吗，继续往下看。

  final Intent verifyBroadcastLocked(Intent intent) {
        // Refuse possible leaked file descriptors
        if (intent != null && intent.hasFileDescriptors() == true) {
            throw new IllegalArgumentException("File descriptors passed in Intent");
        }

        int flags = intent.getFlags();

        if (!mProcessesReady) {
            // if the caller really truly claims to know what they're doing, go
            // ahead and allow the broadcast without launching any receivers
            if ((flags&Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT) != 0) {
                intent = new Intent(intent);
                intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
            } else if ((flags&Intent.FLAG_RECEIVER_REGISTERED_ONLY) == 0) {
                Slog.e(TAG, "Attempt to launch receivers of broadcast intent " + intent
                        + " before boot completion");
                throw new IllegalStateException("Cannot broadcast before boot completed");
            }
        }

        if ((flags&Intent.FLAG_RECEIVER_BOOT_UPGRADE) != 0) {
            throw new IllegalArgumentException(
                    "Can't use FLAG_RECEIVER_BOOT_UPGRADE here");
        }

        return intent;
    }
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再疯狂@一下当初和我说方法不能超过多少行的哥们，老规矩，拆分步骤往下看。有兴趣的自己慢慢看看。

    final int broadcastIntentLocked(ProcessRecord callerApp,
            String callerPackage, Intent intent, String resolvedType,
            IIntentReceiver resultTo, int resultCode, String resultData,
            Bundle resultExtras, String[] requiredPermissions, int appOp, Bundle bOptions,
            boolean ordered, boolean sticky, int callingPid, int callingUid, int userId) {
        intent = new Intent(intent);

        final boolean callerInstantApp = isInstantApp(callerApp, callerPackage, callingUid);
        // Instant Apps cannot use FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS
        if (callerInstantApp) {
            intent.setFlags(intent.getFlags() & ~Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
        }

        // By default broadcasts do not go to stopped apps.
        intent.addFlags(Intent.FLAG_EXCLUDE_STOPPED_PACKAGES);

        // If we have not finished booting, don't allow this to launch new processes.
        if (!mProcessesReady && (intent.getFlags()&Intent.FLAG_RECEIVER_BOOT_UPGRADE) == 0) {
            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
        }

        if (DEBUG_BROADCAST_LIGHT) Slog.v(TAG_BROADCAST,
                (sticky ? "Broadcast sticky: ": "Broadcast: ") + intent
                + " ordered=" + ordered + " userid=" + userId);
        if ((resultTo != null) && !ordered) {
            Slog.w(TAG, "Broadcast " + intent + " not ordered but result callback requested!");
        }

        userId = mUserController.handleIncomingUser(callingPid, callingUid, userId, true,
                ALLOW_NON_FULL, "broadcast", callerPackage);

        // Make sure that the user who is receiving this broadcast is running.
        // If not, we will just skip it. Make an exception for shutdown broadcasts
        // and upgrade steps.

        if (userId != UserHandle.USER_ALL && !mUserController.isUserRunningLocked(userId, 0)) {
            if ((callingUid != SYSTEM_UID
                    || (intent.getFlags() & Intent.FLAG_RECEIVER_BOOT_UPGRADE) == 0)
                    && !Intent.ACTION_SHUTDOWN.equals(intent.getAction())) {
                Slog.w(TAG, "Skipping broadcast of " + intent
                        + ": user " + userId + " is stopped");
                return ActivityManager.BROADCAST_FAILED_USER_STOPPED;
            }
        }

        BroadcastOptions brOptions = null;
        if (bOptions != null) {
            brOptions = new BroadcastOptions(bOptions);
            if (brOptions.getTemporaryAppWhitelistDuration() > 0) {
                // See if the caller is allowed to do this.  Note we are checking against
                // the actual real caller (not whoever provided the operation as say a
                // PendingIntent), because that who is actually supplied the arguments.
                if (checkComponentPermission(
                        android.Manifest.permission.CHANGE_DEVICE_IDLE_TEMP_WHITELIST,
                        Binder.getCallingPid(), Binder.getCallingUid(), -1, true)
                        != PackageManager.PERMISSION_GRANTED) {
                    String msg = "Permission Denial: " + intent.getAction()
                            + " broadcast from " + callerPackage + " (pid=" + callingPid
                            + ", uid=" + callingUid + ")"
                            + " requires "
                            + android.Manifest.permission.CHANGE_DEVICE_IDLE_TEMP_WHITELIST;
                    Slog.w(TAG, msg);
                    throw new SecurityException(msg);
                }
            }
        }

        // Verify that protected broadcasts are only being sent by system code,
        // and that system code is only sending protected broadcasts.
        final String action = intent.getAction();
        final boolean isProtectedBroadcast;
        try {
            isProtectedBroadcast = AppGlobals.getPackageManager().isProtectedBroadcast(action);
        } catch (RemoteException e) {
            Slog.w(TAG, "Remote exception", e);
            return ActivityManager.BROADCAST_SUCCESS;
        }

        final boolean isCallerSystem;
        switch (UserHandle.getAppId(callingUid)) {
            case ROOT_UID:
            case SYSTEM_UID:
            case PHONE_UID:
            case BLUETOOTH_UID:
            case NFC_UID:
                isCallerSystem = true;
                break;
            default:
                isCallerSystem = (callerApp != null) && callerApp.persistent;
                break;
        }

        // First line security check before anything else: stop non-system apps from
        // sending protected broadcasts.
        if (!isCallerSystem) {
            if (isProtectedBroadcast) {
                String msg = "Permission Denial: not allowed to send broadcast "
                        + action + " from pid="
                        + callingPid + ", uid=" + callingUid;
                Slog.w(TAG, msg);
                throw new SecurityException(msg);

            } else if (AppWidgetManager.ACTION_APPWIDGET_CONFIGURE.equals(action)
                    || AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) {
                // Special case for compatibility: we don't want apps to send this,
                // but historically it has not been protected and apps may be using it
                // to poke their own app widget.  So, instead of making it protected,
                // just limit it to the caller.
                if (callerPackage == null) {
                    String msg = "Permission Denial: not allowed to send broadcast "
                            + action + " from unknown caller.";
                    Slog.w(TAG, msg);
                    throw new SecurityException(msg);
                } else if (intent.getComponent() != null) {
                    // They are good enough to send to an explicit component...  verify
                    // it is being sent to the calling app.
                    if (!intent.getComponent().getPackageName().equals(
                            callerPackage)) {
                        String msg = "Permission Denial: not allowed to send broadcast "
                                + action + " to "
                                + intent.getComponent().getPackageName() + " from "
                                + callerPackage;
                        Slog.w(TAG, msg);
                        throw new SecurityException(msg);
                    }
                } else {
                    // Limit broadcast to their own package.
                    intent.setPackage(callerPackage);
                }
            }
        }

        if (action != null) {
            if (getBackgroundLaunchBroadcasts().contains(action)) {
                if (DEBUG_BACKGROUND_CHECK) {
                    Slog.i(TAG, "Broadcast action " + action + " forcing include-background");
                }
                intent.addFlags(Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
            }

            switch (action) {
                case Intent.ACTION_UID_REMOVED:
                case Intent.ACTION_PACKAGE_REMOVED:
                case Intent.ACTION_PACKAGE_CHANGED:
                case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
                case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
                case Intent.ACTION_PACKAGES_SUSPENDED:
                case Intent.ACTION_PACKAGES_UNSUSPENDED:
                    // Handle special intents: if this broadcast is from the package
                    // manager about a package being removed, we need to remove all of
                    // its activities from the history stack.
                    if (checkComponentPermission(
                            android.Manifest.permission.BROADCAST_PACKAGE_REMOVED,
                            callingPid, callingUid, -1, true)
                            != PackageManager.PERMISSION_GRANTED) {
                        String msg = "Permission Denial: " + intent.getAction()
                                + " broadcast from " + callerPackage + " (pid=" + callingPid
                                + ", uid=" + callingUid + ")"
                                + " requires "
                                + android.Manifest.permission.BROADCAST_PACKAGE_REMOVED;
                        Slog.w(TAG, msg);
                        throw new SecurityException(msg);
                    }
                    switch (action) {
                        case Intent.ACTION_UID_REMOVED:
                            final int uid = getUidFromIntent(intent);
                            if (uid >= 0) {
                                mBatteryStatsService.removeUid(uid);
                                mAppOpsService.uidRemoved(uid);
                            }
                            break;
                        case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
                            // If resources are unavailable just force stop all those packages
                            // and flush the attribute cache as well.
                            String list[] =
                                    intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
                            if (list != null && list.length > 0) {
                                for (int i = 0; i < list.length; i++) {
                                    forceStopPackageLocked(list[i], -1, false, true, true,
                                            false, false, userId, "storage unmount");
                                }
                                mRecentTasks.cleanupLocked(UserHandle.USER_ALL);
                                sendPackageBroadcastLocked(
                                        ApplicationThreadConstants.EXTERNAL_STORAGE_UNAVAILABLE,
                                        list, userId);
                            }
                            break;
                        case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
                            mRecentTasks.cleanupLocked(UserHandle.USER_ALL);
                            break;
                        case Intent.ACTION_PACKAGE_REMOVED:
                        case Intent.ACTION_PACKAGE_CHANGED:
                            Uri data = intent.getData();
                            String ssp;
                            if (data != null && (ssp=data.getSchemeSpecificPart()) != null) {
                                boolean removed = Intent.ACTION_PACKAGE_REMOVED.equals(action);
                                final boolean replacing =
                                        intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
                                final boolean killProcess =
                                        !intent.getBooleanExtra(Intent.EXTRA_DONT_KILL_APP, false);
                                final boolean fullUninstall = removed && !replacing;
                                if (removed) {
                                    if (killProcess) {
                                        forceStopPackageLocked(ssp, UserHandle.getAppId(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1)),
                                                false, true, true, false, fullUninstall, userId,
                                                removed ? "pkg removed" : "pkg changed");
                                    }
                                    final int cmd = killProcess
                                            ? ApplicationThreadConstants.PACKAGE_REMOVED
                                            : ApplicationThreadConstants.PACKAGE_REMOVED_DONT_KILL;
                                    sendPackageBroadcastLocked(cmd,
                                            new String[] {ssp}, userId);
                                    if (fullUninstall) {
                                        mAppOpsService.packageRemoved(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1), ssp);

                                        // Remove all permissions granted from/to this package
                                        removeUriPermissionsForPackageLocked(ssp, userId, true);

                                        removeTasksByPackageNameLocked(ssp, userId);

                                        mServices.forceStopPackageLocked(ssp, userId);

                                        // Hide the "unsupported display" dialog if necessary.
                                        if (mUnsupportedDisplaySizeDialog != null && ssp.equals(
                                                mUnsupportedDisplaySizeDialog.getPackageName())) {
                                            mUnsupportedDisplaySizeDialog.dismiss();
                                            mUnsupportedDisplaySizeDialog = null;
                                        }
                                        mCompatModePackages.handlePackageUninstalledLocked(ssp);
                                        mBatteryStatsService.notePackageUninstalled(ssp);
                                    }
                                } else {
                                    if (killProcess) {
                                        killPackageProcessesLocked(ssp, UserHandle.getAppId(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1)),
                                                userId, ProcessList.INVALID_ADJ,
                                                false, true, true, false, "change " + ssp);
                                    }
                                    cleanupDisabledPackageComponentsLocked(ssp, userId, killProcess,
                                            intent.getStringArrayExtra(
                                                    Intent.EXTRA_CHANGED_COMPONENT_NAME_LIST));
                                }
                            }
                            break;
                        case Intent.ACTION_PACKAGES_SUSPENDED:
                        case Intent.ACTION_PACKAGES_UNSUSPENDED:
                            final boolean suspended = Intent.ACTION_PACKAGES_SUSPENDED.equals(
                                    intent.getAction());
                            final String[] packageNames = intent.getStringArrayExtra(
                                    Intent.EXTRA_CHANGED_PACKAGE_LIST);
                            final int userHandle = intent.getIntExtra(
                                    Intent.EXTRA_USER_HANDLE, UserHandle.USER_NULL);

                            synchronized(ActivityManagerService.this) {
                                mRecentTasks.onPackagesSuspendedChanged(
                                        packageNames, suspended, userHandle);
                            }
                            break;
                    }
                    break;
                case Intent.ACTION_PACKAGE_REPLACED:
                {
                    final Uri data = intent.getData();
                    final String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        ApplicationInfo aInfo = null;
                        try {
                            aInfo = AppGlobals.getPackageManager()
                                    .getApplicationInfo(ssp, 0 /*flags*/, userId);
                        } catch (RemoteException ignore) {}
                        if (aInfo == null) {
                            Slog.w(TAG, "Dropping ACTION_PACKAGE_REPLACED for non-existent pkg:"
                                    + " ssp=" + ssp + " data=" + data);
                            return ActivityManager.BROADCAST_SUCCESS;
                        }
                        mStackSupervisor.updateActivityApplicationInfoLocked(aInfo);
                        sendPackageBroadcastLocked(ApplicationThreadConstants.PACKAGE_REPLACED,
                                new String[] {ssp}, userId);
                    }
                    break;
                }
                case Intent.ACTION_PACKAGE_ADDED:
                {
                    // Special case for adding a package: by default turn on compatibility mode.
                    Uri data = intent.getData();
                    String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        final boolean replacing =
                                intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
                        mCompatModePackages.handlePackageAddedLocked(ssp, replacing);

                        try {
                            ApplicationInfo ai = AppGlobals.getPackageManager().
                                    getApplicationInfo(ssp, 0, 0);
                            mBatteryStatsService.notePackageInstalled(ssp,
                                    ai != null ? ai.versionCode : 0);
                        } catch (RemoteException e) {
                        }
                    }
                    break;
                }
                case Intent.ACTION_PACKAGE_DATA_CLEARED:
                {
                    Uri data = intent.getData();
                    String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        // Hide the "unsupported display" dialog if necessary.
                        if (mUnsupportedDisplaySizeDialog != null && ssp.equals(
                                mUnsupportedDisplaySizeDialog.getPackageName())) {
                            mUnsupportedDisplaySizeDialog.dismiss();
                            mUnsupportedDisplaySizeDialog = null;
                        }
                        mCompatModePackages.handlePackageDataClearedLocked(ssp);
                    }
                    break;
                }
                case Intent.ACTION_TIMEZONE_CHANGED:
                    // If this is the time zone changed action, queue up a message that will reset
                    // the timezone of all currently running processes. This message will get
                    // queued up before the broadcast happens.
                    mHandler.sendEmptyMessage(UPDATE_TIME_ZONE);
                    break;
                case Intent.ACTION_TIME_CHANGED:
                    // EXTRA_TIME_PREF_24_HOUR_FORMAT is optional so we must distinguish between
                    // the tri-state value it may contain and "unknown".
                    // For convenience we re-use the Intent extra values.
                    final int NO_EXTRA_VALUE_FOUND = -1;
                    final int timeFormatPreferenceMsgValue = intent.getIntExtra(
                            Intent.EXTRA_TIME_PREF_24_HOUR_FORMAT,
                            NO_EXTRA_VALUE_FOUND /* defaultValue */);
                    // Only send a message if the time preference is available.
                    if (timeFormatPreferenceMsgValue != NO_EXTRA_VALUE_FOUND) {
                        Message updateTimePreferenceMsg =
                                mHandler.obtainMessage(UPDATE_TIME_PREFERENCE_MSG,
                                        timeFormatPreferenceMsgValue, 0);
                        mHandler.sendMessage(updateTimePreferenceMsg);
                    }
                    BatteryStatsImpl stats = mBatteryStatsService.getActiveStatistics();
                    synchronized (stats) {
                        stats.noteCurrentTimeChangedLocked();
                    }
                    break;
                case Intent.ACTION_CLEAR_DNS_CACHE:
                    mHandler.sendEmptyMessage(CLEAR_DNS_CACHE_MSG);
                    break;
                case Proxy.PROXY_CHANGE_ACTION:
                    ProxyInfo proxy = intent.getParcelableExtra(Proxy.EXTRA_PROXY_INFO);
                    mHandler.sendMessage(mHandler.obtainMessage(UPDATE_HTTP_PROXY_MSG, proxy));
                    break;
                case android.hardware.Camera.ACTION_NEW_PICTURE:
                case android.hardware.Camera.ACTION_NEW_VIDEO:
                    // In N we just turned these off; in O we are turing them back on partly,
                    // only for registered receivers.  This will still address the main problem
                    // (a spam of apps waking up when a picture is taken putting significant
                    // memory pressure on the system at a bad point), while still allowing apps
                    // that are already actively running to know about this happening.
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
                    break;
                case android.security.KeyChain.ACTION_TRUST_STORE_CHANGED:
                    mHandler.sendEmptyMessage(HANDLE_TRUST_STORAGE_UPDATE_MSG);
                    break;
                case "com.android.launcher.action.INSTALL_SHORTCUT":
                    // As of O, we no longer support this broadcasts, even for pre-O apps.
                    // Apps should now be using ShortcutManager.pinRequestShortcut().
                    Log.w(TAG, "Broadcast " + action
                            + " no longer supported. It will not be delivered.");
                    return ActivityManager.BROADCAST_SUCCESS;
            }

            if (Intent.ACTION_PACKAGE_ADDED.equals(action) ||
                    Intent.ACTION_PACKAGE_REMOVED.equals(action) ||
                    Intent.ACTION_PACKAGE_REPLACED.equals(action)) {
                final int uid = getUidFromIntent(intent);
                if (uid != -1) {
                    final UidRecord uidRec = mActiveUids.get(uid);
                    if (uidRec != null) {
                        uidRec.updateHasInternetPermission();
                    }
                }
            }
        }

        // Add to the sticky list if requested.
        if (sticky) {
            if (checkPermission(android.Manifest.permission.BROADCAST_STICKY,
                    callingPid, callingUid)
                    != PackageManager.PERMISSION_GRANTED) {
                String msg = "Permission Denial: broadcastIntent() requesting a sticky broadcast from pid="
                        + callingPid + ", uid=" + callingUid
                        + " requires " + android.Manifest.permission.BROADCAST_STICKY;
                Slog.w(TAG, msg);
                throw new SecurityException(msg);
            }
            if (requiredPermissions != null && requiredPermissions.length > 0) {
                Slog.w(TAG, "Can't broadcast sticky intent " + intent
                        + " and enforce permissions " + Arrays.toString(requiredPermissions));
                return ActivityManager.BROADCAST_STICKY_CANT_HAVE_PERMISSION;
            }
            if (intent.getComponent() != null) {
                throw new SecurityException(
                        "Sticky broadcasts can't target a specific component");
            }
            // We use userId directly here, since the "all" target is maintained
            // as a separate set of sticky broadcasts.
            if (userId != UserHandle.USER_ALL) {
                // But first, if this is not a broadcast to all users, then
                // make sure it doesn't conflict with an existing broadcast to
                // all users.
                ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(
                        UserHandle.USER_ALL);
                if (stickies != null) {
                    ArrayList<Intent> list = stickies.get(intent.getAction());
                    if (list != null) {
                        int N = list.size();
                        int i;
                        for (i=0; i<N; i++) {
                            if (intent.filterEquals(list.get(i))) {
                                throw new IllegalArgumentException(
                                        "Sticky broadcast " + intent + " for user "
                                        + userId + " conflicts with existing global broadcast");
                            }
                        }
                    }
                }
            }
            ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(userId);
            if (stickies == null) {
                stickies = new ArrayMap<>();
                mStickyBroadcasts.put(userId, stickies);
            }
            ArrayList<Intent> list = stickies.get(intent.getAction());
            if (list == null) {
                list = new ArrayList<>();
                stickies.put(intent.getAction(), list);
            }
            final int stickiesCount = list.size();
            int i;
            for (i = 0; i < stickiesCount; i++) {
                if (intent.filterEquals(list.get(i))) {
                    // This sticky already exists, replace it.
                    list.set(i, new Intent(intent));
                    break;
                }
            }
            if (i >= stickiesCount) {
                list.add(new Intent(intent));
            }
        }

        int[] users;
        if (userId == UserHandle.USER_ALL) {
            // Caller wants broadcast to go to all started users.
            users = mUserController.getStartedUserArrayLocked();
        } else {
            // Caller wants broadcast to go to one specific user.
            users = new int[] {userId};
        }

        // Figure out who all will receive this broadcast.
        List receivers = null;
        List<BroadcastFilter> registeredReceivers = null;
        // Need to resolve the intent to interested receivers...
        if ((intent.getFlags()&Intent.FLAG_RECEIVER_REGISTERED_ONLY)
                 == 0) {
            receivers = collectReceiverComponents(intent, resolvedType, callingUid, users);
        }
        if (intent.getComponent() == null) {
            if (userId == UserHandle.USER_ALL && callingUid == SHELL_UID) {
                // Query one target user at a time, excluding shell-restricted users
                for (int i = 0; i < users.length; i++) {
                    if (mUserController.hasUserRestriction(
                            UserManager.DISALLOW_DEBUGGING_FEATURES, users[i])) {
                        continue;
                    }
                    List<BroadcastFilter> registeredReceiversForUser =
                            mReceiverResolver.queryIntent(intent,
                                    resolvedType, false /*defaultOnly*/, users[i]);
                    if (registeredReceivers == null) {
                        registeredReceivers = registeredReceiversForUser;
                    } else if (registeredReceiversForUser != null) {
                        registeredReceivers.addAll(registeredReceiversForUser);
                    }
                }
            } else {
                registeredReceivers = mReceiverResolver.queryIntent(intent,
                        resolvedType, false /*defaultOnly*/, userId);
            }
        }

        final boolean replacePending =
                (intent.getFlags()&Intent.FLAG_RECEIVER_REPLACE_PENDING) != 0;

        if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing broadcast: " + intent.getAction()
                + " replacePending=" + replacePending);

        int NR = registeredReceivers != null ? registeredReceivers.size() : 0;
        if (!ordered && NR > 0) {
            // If we are not serializing this broadcast, then send the
            // registered receivers separately so they don't wait for the
            // components to be launched.
            if (isCallerSystem) {
                checkBroadcastFromSystem(intent, callerApp, callerPackage, callingUid,
                        isProtectedBroadcast, registeredReceivers);
            }
            final BroadcastQueue queue = broadcastQueueForIntent(intent);
            BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
                    callerPackage, callingPid, callingUid, callerInstantApp, resolvedType,
                    requiredPermissions, appOp, brOptions, registeredReceivers, resultTo,
                    resultCode, resultData, resultExtras, ordered, sticky, false, userId);
            if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing parallel broadcast " + r);
            final boolean replaced = replacePending
                    && (queue.replaceParallelBroadcastLocked(r) != null);
            // Note: We assume resultTo is null for non-ordered broadcasts.
            if (!replaced) {
                queue.enqueueParallelBroadcastLocked(r);
                queue.scheduleBroadcastsLocked();
            }
            registeredReceivers = null;
            NR = 0;
        }

        // Merge into one list.
        int ir = 0;
        if (receivers != null) {
            // A special case for PACKAGE_ADDED: do not allow the package
            // being added to see this broadcast.  This prevents them from
            // using this as a back door to get run as soon as they are
            // installed.  Maybe in the future we want to have a special install
            // broadcast or such for apps, but we'd like to deliberately make
            // this decision.
            String skipPackages[] = null;
            if (Intent.ACTION_PACKAGE_ADDED.equals(intent.getAction())
                    || Intent.ACTION_PACKAGE_RESTARTED.equals(intent.getAction())
                    || Intent.ACTION_PACKAGE_DATA_CLEARED.equals(intent.getAction())) {
                Uri data = intent.getData();
                if (data != null) {
                    String pkgName = data.getSchemeSpecificPart();
                    if (pkgName != null) {
                        skipPackages = new String[] { pkgName };
                    }
                }
            } else if (Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE.equals(intent.getAction())) {
                skipPackages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
            }
            if (skipPackages != null && (skipPackages.length > 0)) {
                for (String skipPackage : skipPackages) {
                    if (skipPackage != null) {
                        int NT = receivers.size();
                        for (int it=0; it<NT; it++) {
                            ResolveInfo curt = (ResolveInfo)receivers.get(it);
                            if (curt.activityInfo.packageName.equals(skipPackage)) {
                                receivers.remove(it);
                                it--;
                                NT--;
                            }
                        }
                    }
                }
            }

            int NT = receivers != null ? receivers.size() : 0;
            int it = 0;
            ResolveInfo curt = null;
            BroadcastFilter curr = null;
            while (it < NT && ir < NR) {
                if (curt == null) {
                    curt = (ResolveInfo)receivers.get(it);
                }
                if (curr == null) {
                    curr = registeredReceivers.get(ir);
                }
                if (curr.getPriority() >= curt.priority) {
                    // Insert this broadcast record into the final list.
                    receivers.add(it, curr);
                    ir++;
                    curr = null;
                    it++;
                    NT++;
                } else {
                    // Skip to the next ResolveInfo in the final list.
                    it++;
                    curt = null;
                }
            }
        }
        while (ir < NR) {
            if (receivers == null) {
                receivers = new ArrayList();
            }
            receivers.add(registeredReceivers.get(ir));
            ir++;
        }

        if (isCallerSystem) {
            checkBroadcastFromSystem(intent, callerApp, callerPackage, callingUid,
                    isProtectedBroadcast, receivers);
        }

        if ((receivers != null && receivers.size() > 0)
                || resultTo != null) {
            BroadcastQueue queue = broadcastQueueForIntent(intent);
            BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
                    callerPackage, callingPid, callingUid, callerInstantApp, resolvedType,
                    requiredPermissions, appOp, brOptions, receivers, resultTo, resultCode,
                    resultData, resultExtras, ordered, sticky, false, userId);

            if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing ordered broadcast " + r
                    + ": prev had " + queue.mOrderedBroadcasts.size());
            if (DEBUG_BROADCAST) Slog.i(TAG_BROADCAST,
                    "Enqueueing broadcast " + r.intent.getAction());

            final BroadcastRecord oldRecord =
                    replacePending ? queue.replaceOrderedBroadcastLocked(r) : null;
            if (oldRecord != null) {
                // Replaced, fire the result-to receiver.
                if (oldRecord.resultTo != null) {
                    final BroadcastQueue oldQueue = broadcastQueueForIntent(oldRecord.intent);
                    try {
                        oldQueue.performReceiveLocked(oldRecord.callerApp, oldRecord.resultTo,
                                oldRecord.intent,
                                Activity.RESULT_CANCELED, null, null,
                                false, false, oldRecord.userId);
                    } catch (RemoteException e) {
                        Slog.w(TAG, "Failure ["
                                + queue.mQueueName + "] sending broadcast result of "
                                + intent, e);

                    }
                }
            } else {
                queue.enqueueOrderedBroadcastLocked(r);
                queue.scheduleBroadcastsLocked();
            }
        } else {
            // There was nobody interested in the broadcast, but we still want to record
            // that it happened.
            if (intent.getComponent() == null && intent.getPackage() == null
                    && (intent.getFlags()&Intent.FLAG_RECEIVER_REGISTERED_ONLY) == 0) {
                // This was an implicit broadcast... let's record it for posterity.
                addBroadcastStatLocked(intent.getAction(), callerPackage, 0, 0, 0);
            }
        }

        return ActivityManager.BROADCAST_SUCCESS;
    }
         
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broadcastIntentLocked 函数主要功能

1 移除Stopped Package来接收此广播
2 判断广播是否是PRE_Boot接收
3 Protected broadcast
4 特殊ACTION处理
5 StickBroadcast
6 Sticky广播数据结构
7 根据Intent Figure out 对应的Receiver
8 优先处理并行广播
9 处理静态注册Receiver和Order动态广播
10 整理mReceiver和registeredReceivers
11 无Receiver接收此Intent仅记录
12 开始进入广播队列BroadcastQeueue
13 scheduleBroadcastsLocked

1.移除Stopped Package来接收此广播

     intent = new Intent(intent);

        final boolean callerInstantApp = isInstantApp(callerApp, callerPackage, callingUid);
        // Instant Apps cannot use FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS
        if (callerInstantApp) {
            intent.setFlags(intent.getFlags() & ~Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
        }

        // By default broadcasts do not go to stopped apps.
        intent.addFlags(Intent.FLAG_EXCLUDE_STOPPED_PACKAGES);
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FLAG_INCLUDE_STOPPED_PACKAGES
FLAG_EXCLUDE_STOPPED_PACKAGES
广播目前存在两个flag，广播的发送是否包含已经停止的进程，这也是为了提高Android的安全性。

2. 判断广播是否是PRE_Boot接收

   // If we have not finished booting, don't allow this to launch new processes.
        if (!mProcessesReady && (intent.getFlags()&Intent.FLAG_RECEIVER_BOOT_UPGRADE) == 0) {
            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
        }

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是否启动完成，没有完成的话添加 Intent.FLAG_RECEIVER_REGISTERED_ONLY，为什么会有这样的操作呢，做个之后博客的铺垫，Android的静态注册广播其实是PackageManagerService对于xml文件的解析，如果说系统还没有ready，完全有可能存在xml还没有解析完成。这个时候加上之前的那个flag，我们就只对于动态注册的广播进行处理。反正没有ready的时候，静态广播也可能存在不准确的情况，那好我干脆就不去处理了。

3. Protected broadcast

protected-broadcast用来指定一个广播，该广播只能被系统发送，如果普通APP在自己的xml里声明了这些广播，发送时也会被提示错误。“Permission Denial: not allowed to send broadcast”。
ProtectedBroadcast,主要定义在系统级应用的Manfiest.xml中，可见frameworks/base/core/res/AndroidManifest.xml

        // First line security check before anything else: stop non-system apps from
        // sending protected broadcasts.
        if (!isCallerSystem) {
            if (isProtectedBroadcast) {
                String msg = "Permission Denial: not allowed to send broadcast "
                        + action + " from pid="
                        + callingPid + ", uid=" + callingUid;
                Slog.w(TAG, msg);
                throw new SecurityException(msg);

            } else if (AppWidgetManager.ACTION_APPWIDGET_CONFIGURE.equals(action)
                    || AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) {
                // Special case for compatibility: we don't want apps to send this,
                // but historically it has not been protected and apps may be using it
                // to poke their own app widget.  So, instead of making it protected,
                // just limit it to the caller.
                if (callerPackage == null) {
                    String msg = "Permission Denial: not allowed to send broadcast "
                            + action + " from unknown caller.";
                    Slog.w(TAG, msg);
                    throw new SecurityException(msg);
                } else if (intent.getComponent() != null) {
                    // They are good enough to send to an explicit component...  verify
                    // it is being sent to the calling app.
                    if (!intent.getComponent().getPackageName().equals(
                            callerPackage)) {
                        String msg = "Permission Denial: not allowed to send broadcast "
                                + action + " to "
                                + intent.getComponent().getPackageName() + " from "
                                + callerPackage;
                        Slog.w(TAG, msg);
                        throw new SecurityException(msg);
                    }
                } else {
                    // Limit broadcast to their own package.
                    intent.setPackage(callerPackage);
                }
            }
        }
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4 特殊ACTION处理

这个就很明显对于action的处理，有兴趣或者用到了自己看看哈。

        if (action != null) {
            if (getBackgroundLaunchBroadcasts().contains(action)) {
                if (DEBUG_BACKGROUND_CHECK) {
                    Slog.i(TAG, "Broadcast action " + action + " forcing include-background");
                }
                intent.addFlags(Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
            }

            switch (action) {
                case Intent.ACTION_UID_REMOVED:
                case Intent.ACTION_PACKAGE_REMOVED:
                case Intent.ACTION_PACKAGE_CHANGED:
                case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
                case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
                case Intent.ACTION_PACKAGES_SUSPENDED:
                case Intent.ACTION_PACKAGES_UNSUSPENDED:
                    // Handle special intents: if this broadcast is from the package
                    // manager about a package being removed, we need to remove all of
                    // its activities from the history stack.
                    if (checkComponentPermission(
                            android.Manifest.permission.BROADCAST_PACKAGE_REMOVED,
                            callingPid, callingUid, -1, true)
                            != PackageManager.PERMISSION_GRANTED) {
                        String msg = "Permission Denial: " + intent.getAction()
                                + " broadcast from " + callerPackage + " (pid=" + callingPid
                                + ", uid=" + callingUid + ")"
                                + " requires "
                                + android.Manifest.permission.BROADCAST_PACKAGE_REMOVED;
                        Slog.w(TAG, msg);
                        throw new SecurityException(msg);
                    }
                    switch (action) {
                        case Intent.ACTION_UID_REMOVED:
                            final int uid = getUidFromIntent(intent);
                            if (uid >= 0) {
                                mBatteryStatsService.removeUid(uid);
                                mAppOpsService.uidRemoved(uid);
                            }
                            break;
                        case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
                            // If resources are unavailable just force stop all those packages
                            // and flush the attribute cache as well.
                            String list[] =
                                    intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
                            if (list != null && list.length > 0) {
                                for (int i = 0; i < list.length; i++) {
                                    forceStopPackageLocked(list[i], -1, false, true, true,
                                            false, false, userId, "storage unmount");
                                }
                                mRecentTasks.cleanupLocked(UserHandle.USER_ALL);
                                sendPackageBroadcastLocked(
                                        ApplicationThreadConstants.EXTERNAL_STORAGE_UNAVAILABLE,
                                        list, userId);
                            }
                            break;
                        case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
                            mRecentTasks.cleanupLocked(UserHandle.USER_ALL);
                            break;
                        case Intent.ACTION_PACKAGE_REMOVED:
                        case Intent.ACTION_PACKAGE_CHANGED:
                            Uri data = intent.getData();
                            String ssp;
                            if (data != null && (ssp=data.getSchemeSpecificPart()) != null) {
                                boolean removed = Intent.ACTION_PACKAGE_REMOVED.equals(action);
                                final boolean replacing =
                                        intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
                                final boolean killProcess =
                                        !intent.getBooleanExtra(Intent.EXTRA_DONT_KILL_APP, false);
                                final boolean fullUninstall = removed && !replacing;
                                if (removed) {
                                    if (killProcess) {
                                        forceStopPackageLocked(ssp, UserHandle.getAppId(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1)),
                                                false, true, true, false, fullUninstall, userId,
                                                removed ? "pkg removed" : "pkg changed");
                                    }
                                    final int cmd = killProcess
                                            ? ApplicationThreadConstants.PACKAGE_REMOVED
                                            : ApplicationThreadConstants.PACKAGE_REMOVED_DONT_KILL;
                                    sendPackageBroadcastLocked(cmd,
                                            new String[] {ssp}, userId);
                                    if (fullUninstall) {
                                        mAppOpsService.packageRemoved(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1), ssp);

                                        // Remove all permissions granted from/to this package
                                        removeUriPermissionsForPackageLocked(ssp, userId, true);

                                        removeTasksByPackageNameLocked(ssp, userId);

                                        mServices.forceStopPackageLocked(ssp, userId);

                                        // Hide the "unsupported display" dialog if necessary.
                                        if (mUnsupportedDisplaySizeDialog != null && ssp.equals(
                                                mUnsupportedDisplaySizeDialog.getPackageName())) {
                                            mUnsupportedDisplaySizeDialog.dismiss();
                                            mUnsupportedDisplaySizeDialog = null;
                                        }
                                        mCompatModePackages.handlePackageUninstalledLocked(ssp);
                                        mBatteryStatsService.notePackageUninstalled(ssp);
                                    }
                                } else {
                                    if (killProcess) {
                                        killPackageProcessesLocked(ssp, UserHandle.getAppId(
                                                intent.getIntExtra(Intent.EXTRA_UID, -1)),
                                                userId, ProcessList.INVALID_ADJ,
                                                false, true, true, false, "change " + ssp);
                                    }
                                    cleanupDisabledPackageComponentsLocked(ssp, userId, killProcess,
                                            intent.getStringArrayExtra(
                                                    Intent.EXTRA_CHANGED_COMPONENT_NAME_LIST));
                                }
                            }
                            break;
                        case Intent.ACTION_PACKAGES_SUSPENDED:
                        case Intent.ACTION_PACKAGES_UNSUSPENDED:
                            final boolean suspended = Intent.ACTION_PACKAGES_SUSPENDED.equals(
                                    intent.getAction());
                            final String[] packageNames = intent.getStringArrayExtra(
                                    Intent.EXTRA_CHANGED_PACKAGE_LIST);
                            final int userHandle = intent.getIntExtra(
                                    Intent.EXTRA_USER_HANDLE, UserHandle.USER_NULL);

                            synchronized(ActivityManagerService.this) {
                                mRecentTasks.onPackagesSuspendedChanged(
                                        packageNames, suspended, userHandle);
                            }
                            break;
                    }
                    break;
                case Intent.ACTION_PACKAGE_REPLACED:
                {
                    final Uri data = intent.getData();
                    final String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        ApplicationInfo aInfo = null;
                        try {
                            aInfo = AppGlobals.getPackageManager()
                                    .getApplicationInfo(ssp, 0 /*flags*/, userId);
                        } catch (RemoteException ignore) {}
                        if (aInfo == null) {
                            Slog.w(TAG, "Dropping ACTION_PACKAGE_REPLACED for non-existent pkg:"
                                    + " ssp=" + ssp + " data=" + data);
                            return ActivityManager.BROADCAST_SUCCESS;
                        }
                        mStackSupervisor.updateActivityApplicationInfoLocked(aInfo);
                        sendPackageBroadcastLocked(ApplicationThreadConstants.PACKAGE_REPLACED,
                                new String[] {ssp}, userId);
                    }
                    break;
                }
                case Intent.ACTION_PACKAGE_ADDED:
                {
                    // Special case for adding a package: by default turn on compatibility mode.
                    Uri data = intent.getData();
                    String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        final boolean replacing =
                                intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
                        mCompatModePackages.handlePackageAddedLocked(ssp, replacing);

                        try {
                            ApplicationInfo ai = AppGlobals.getPackageManager().
                                    getApplicationInfo(ssp, 0, 0);
                            mBatteryStatsService.notePackageInstalled(ssp,
                                    ai != null ? ai.versionCode : 0);
                        } catch (RemoteException e) {
                        }
                    }
                    break;
                }
                case Intent.ACTION_PACKAGE_DATA_CLEARED:
                {
                    Uri data = intent.getData();
                    String ssp;
                    if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
                        // Hide the "unsupported display" dialog if necessary.
                        if (mUnsupportedDisplaySizeDialog != null && ssp.equals(
                                mUnsupportedDisplaySizeDialog.getPackageName())) {
                            mUnsupportedDisplaySizeDialog.dismiss();
                            mUnsupportedDisplaySizeDialog = null;
                        }
                        mCompatModePackages.handlePackageDataClearedLocked(ssp);
                    }
                    break;
                }
                case Intent.ACTION_TIMEZONE_CHANGED:
                    // If this is the time zone changed action, queue up a message that will reset
                    // the timezone of all currently running processes. This message will get
                    // queued up before the broadcast happens.
                    mHandler.sendEmptyMessage(UPDATE_TIME_ZONE);
                    break;
                case Intent.ACTION_TIME_CHANGED:
                    // EXTRA_TIME_PREF_24_HOUR_FORMAT is optional so we must distinguish between
                    // the tri-state value it may contain and "unknown".
                    // For convenience we re-use the Intent extra values.
                    final int NO_EXTRA_VALUE_FOUND = -1;
                    final int timeFormatPreferenceMsgValue = intent.getIntExtra(
                            Intent.EXTRA_TIME_PREF_24_HOUR_FORMAT,
                            NO_EXTRA_VALUE_FOUND /* defaultValue */);
                    // Only send a message if the time preference is available.
                    if (timeFormatPreferenceMsgValue != NO_EXTRA_VALUE_FOUND) {
                        Message updateTimePreferenceMsg =
                                mHandler.obtainMessage(UPDATE_TIME_PREFERENCE_MSG,
                                        timeFormatPreferenceMsgValue, 0);
                        mHandler.sendMessage(updateTimePreferenceMsg);
                    }
                    BatteryStatsImpl stats = mBatteryStatsService.getActiveStatistics();
                    synchronized (stats) {
                        stats.noteCurrentTimeChangedLocked();
                    }
                    break;
                case Intent.ACTION_CLEAR_DNS_CACHE:
                    mHandler.sendEmptyMessage(CLEAR_DNS_CACHE_MSG);
                    break;
                case Proxy.PROXY_CHANGE_ACTION:
                    ProxyInfo proxy = intent.getParcelableExtra(Proxy.EXTRA_PROXY_INFO);
                    mHandler.sendMessage(mHandler.obtainMessage(UPDATE_HTTP_PROXY_MSG, proxy));
                    break;
                case android.hardware.Camera.ACTION_NEW_PICTURE:
                case android.hardware.Camera.ACTION_NEW_VIDEO:
                    // In N we just turned these off; in O we are turing them back on partly,
                    // only for registered receivers.  This will still address the main problem
                    // (a spam of apps waking up when a picture is taken putting significant
                    // memory pressure on the system at a bad point), while still allowing apps
                    // that are already actively running to know about this happening.
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
                    break;
                case android.security.KeyChain.ACTION_TRUST_STORE_CHANGED:
                    mHandler.sendEmptyMessage(HANDLE_TRUST_STORAGE_UPDATE_MSG);
                    break;
                case "com.android.launcher.action.INSTALL_SHORTCUT":
                    // As of O, we no longer support this broadcasts, even for pre-O apps.
                    // Apps should now be using ShortcutManager.pinRequestShortcut().
                    Log.w(TAG, "Broadcast " + action
                            + " no longer supported. It will not be delivered.");
                    return ActivityManager.BROADCAST_SUCCESS;
            }

            if (Intent.ACTION_PACKAGE_ADDED.equals(action) ||
                    Intent.ACTION_PACKAGE_REMOVED.equals(action) ||
                    Intent.ACTION_PACKAGE_REPLACED.equals(action)) {
                final int uid = getUidFromIntent(intent);
                if (uid != -1) {
                    final UidRecord uidRec = mActiveUids.get(uid);
                    if (uidRec != null) {
                        uidRec.updateHasInternetPermission();
                    }
                }
            }
        }
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5 StickBroadcast

判断粘性广播，并且更新stickies。

       // Add to the sticky list if requested.
        if (sticky) {
            if (checkPermission(android.Manifest.permission.BROADCAST_STICKY,
                    callingPid, callingUid)
                    != PackageManager.PERMISSION_GRANTED) {
                String msg = "Permission Denial: broadcastIntent() requesting a sticky broadcast from pid="
                        + callingPid + ", uid=" + callingUid
                        + " requires " + android.Manifest.permission.BROADCAST_STICKY;
                Slog.w(TAG, msg);
                throw new SecurityException(msg);
            }
            if (requiredPermissions != null && requiredPermissions.length > 0) {
                Slog.w(TAG, "Can't broadcast sticky intent " + intent
                        + " and enforce permissions " + Arrays.toString(requiredPermissions));
                return ActivityManager.BROADCAST_STICKY_CANT_HAVE_PERMISSION;
            }
            if (intent.getComponent() != null) {
                throw new SecurityException(
                        "Sticky broadcasts can't target a specific component");
            }
            // We use userId directly here, since the "all" target is maintained
            // as a separate set of sticky broadcasts.
            if (userId != UserHandle.USER_ALL) {
                // But first, if this is not a broadcast to all users, then
                // make sure it doesn't conflict with an existing broadcast to
                // all users.
                ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(
                        UserHandle.USER_ALL);
                if (stickies != null) {
                    ArrayList<Intent> list = stickies.get(intent.getAction());
                    if (list != null) {
                        int N = list.size();
                        int i;
                        for (i=0; i<N; i++) {
                            if (intent.filterEquals(list.get(i))) {
                                throw new IllegalArgumentException(
                                        "Sticky broadcast " + intent + " for user "
                                        + userId + " conflicts with existing global broadcast");
                            }
                        }
                    }
                }
            }
            ArrayMap<String, ArrayList<Intent>> stickies = mStickyBroadcasts.get(userId);
            if (stickies == null) {
                stickies = new ArrayMap<>();
                mStickyBroadcasts.put(userId, stickies);
            }
            ArrayList<Intent> list = stickies.get(intent.getAction());
            if (list == null) {
                list = new ArrayList<>();
                stickies.put(intent.getAction(), list);
            }
            final int stickiesCount = list.size();
            int i;
            for (i = 0; i < stickiesCount; i++) {
                if (intent.filterEquals(list.get(i))) {
                    // This sticky already exists, replace it.
                    list.set(i, new Intent(intent));
                    break;
                }
            }
            if (i >= stickiesCount) {
                list.add(new Intent(intent));
            }
        }
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6 根据Intent Figure out 对应的Receiver

根据intent匹配出Receiver，其实就是查询，储存，为下一步发送做准备，你总得知道我们需要发给谁，对吧。
receivers静态注册的接收者
registeredReceivers所有动态注册的接收者

 // Figure out who all will receive this broadcast.
        List receivers = null;
        List<BroadcastFilter> registeredReceivers = null;
        // Need to resolve the intent to interested receivers...
        if ((intent.getFlags()&Intent.FLAG_RECEIVER_REGISTERED_ONLY)
                 == 0) {
            receivers = collectReceiverComponents(intent, resolvedType, callingUid, users);
        }
        if (intent.getComponent() == null) {
            if (userId == UserHandle.USER_ALL && callingUid == SHELL_UID) {
                // Query one target user at a time, excluding shell-restricted users
                for (int i = 0; i < users.length; i++) {
                    if (mUserController.hasUserRestriction(
                            UserManager.DISALLOW_DEBUGGING_FEATURES, users[i])) {
                        continue;
                    }
                    List<BroadcastFilter> registeredReceiversForUser =
                            mReceiverResolver.queryIntent(intent,
                                    resolvedType, false /*defaultOnly*/, users[i]);
                    if (registeredReceivers == null) {
                        registeredReceivers = registeredReceiversForUser;
                    } else if (registeredReceiversForUser != null) {
                        registeredReceivers.addAll(registeredReceiversForUser);
                    }
                }
            } else {
                registeredReceivers = mReceiverResolver.queryIntent(intent,
                        resolvedType, false /*defaultOnly*/, userId);
            }
        }
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8 优先处理并行广播

        final boolean replacePending =
                (intent.getFlags()&Intent.FLAG_RECEIVER_REPLACE_PENDING) != 0;

        if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing broadcast: " + intent.getAction()
                + " replacePending=" + replacePending);

        int NR = registeredReceivers != null ? registeredReceivers.size() : 0;
        if (!ordered && NR > 0) {
            // If we are not serializing this broadcast, then send the
            // registered receivers separately so they don't wait for the
            // components to be launched.
            if (isCallerSystem) {
                checkBroadcastFromSystem(intent, callerApp, callerPackage, callingUid,
                        isProtectedBroadcast, registeredReceivers);
            }
            final BroadcastQueue queue = broadcastQueueForIntent(intent);
            BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
                    callerPackage, callingPid, callingUid, callerInstantApp, resolvedType,
                    requiredPermissions, appOp, brOptions, registeredReceivers, resultTo,
                    resultCode, resultData, resultExtras, ordered, sticky, false, userId);
            if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing parallel broadcast " + r);
            final boolean replaced = replacePending
                    && (queue.replaceParallelBroadcastLocked(r) != null);
            // Note: We assume resultTo is null for non-ordered broadcasts.
            if (!replaced) {
                queue.enqueueParallelBroadcastLocked(r);
                queue.scheduleBroadcastsLocked();
            }
            registeredReceivers = null;
            NR = 0;
        }
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9 处理静态注册Receiver和Order动态广播

将最终的结果发给BroadCastQueue

    if ((receivers != null && receivers.size() > 0)
            || resultTo != null) {
        BroadcastQueue queue = broadcastQueueForIntent(intent);
        BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
                callerPackage, callingPid, callingUid, resolvedType,
                requiredPermissions, appOp, brOptions, receivers, resultTo, resultCode,
                resultData, resultExtras, ordered, sticky, false, userId);
        if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Enqueueing ordered broadcast " + r
                + ": prev had " + queue.mOrderedBroadcasts.size());
        if (DEBUG_BROADCAST) Slog.i(TAG_BROADCAST,
                "Enqueueing broadcast " + r.intent.getAction());
        boolean replaced = replacePending && queue.replaceOrderedBroadcastLocked(r);
        if (!replaced) {
            queue.enqueueOrderedBroadcastLocked(r);
            queue.scheduleBroadcastsLocked();
        }
    } else {
        // There was nobody interested in the broadcast, but we still want to record
        // that it happened.
        if (intent.getComponent() == null && intent.getPackage() == null
                && (intent.getFlags()&Intent.FLAG_RECEIVER_REGISTERED_ONLY) == 0) {
            // This was an implicit broadcast... let's record it for posterity.
            addBroadcastStatLocked(intent.getAction(), callerPackage, 0, 0, 0);
        }
    }
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10 整理mReceiver和registeredReceivers

mParallelBroadcasts表中，每个BroadcastRecord只可能携带BroadcastFilter，因为平行处理的节点只会对应动态receiver，
而所有静态receiver只能是串行处理的，另一方面，在mOrderedBroadcasts表中BroadcastRecord中则既可能携带BroadcastFilter，也可能携带ResolveInfo。这个其实很容易理解，

mReceiver解析

首先，ResolveInfo对应静态receiver，放到这里自不待言，
其次，如果用户在发送广播时明确指定要按ordered方式发送的话，那么即使目标方的receiver是动态注册的，它对应的BroadcastFilter也会被强制放到这里。

 public void enqueueParallelBroadcastLocked(BroadcastRecord r) {
        mParallelBroadcasts.add(r);
    }

    public void enqueueOrderedBroadcastLocked(BroadcastRecord r) {
        mOrderedBroadcasts.add(r);
    }
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AMS其实是调用这两个方法在解析判断后add到对应的数据结构当中。

11 开始进入广播队列BroadcastQeueue

调用scheduleBroadcastsLocked(),进入到BroadcastQeueue。

    public void scheduleBroadcastsLocked() {
        if (DEBUG_BROADCAST) Slog.v(TAG, "Schedule broadcasts ["
                + mQueueName + "]: current="
                + mBroadcastsScheduled);

        if (mBroadcastsScheduled) {
            return;
        }
        mHandler.sendMessage(mHandler.obtainMessage(BROADCAST_INTENT_MSG, this));
        mBroadcastsScheduled = true;
    }

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12 scheduleBroadcastsLocked

之后，我们最终会调用到BroadcastQeueue的processNextBroadcast()方法。
来来来，划重点，前面我曾经说过一个问题，静态注册的广播先接收到还是动态注册的广播先接收到呢。先给出答案：动态广播 > 静态注册的广播。
我们应该知道的是，我们可以通过静态广播，当进程死掉的时候，发送这个广播将他拉起来但是动态却不能实现，他比静态广播可少步骤啊，那好吧，google的思想就是先把简单的处理了再处理复杂的，至少有个快的，对不对。所以，他们选择优先处理并行广播。
首先我们会处理平行广播。

    // First, deliver any non-serialized broadcasts right away.
            while (mParallelBroadcasts.size() > 0) {
                r = mParallelBroadcasts.remove(0);
                r.dispatchTime = SystemClock.uptimeMillis();
                r.dispatchClockTime = System.currentTimeMillis();
                final int N = r.receivers.size();
                if (DEBUG_BROADCAST_LIGHT) Slog.v(TAG, "Processing parallel broadcast ["
                        + mQueueName + "] " + r);
                for (int i=0; i<N; i++) {
                    Object target = r.receivers.get(i);
                    if (DEBUG_BROADCAST)  Slog.v(TAG,
                            "Delivering non-ordered on [" + mQueueName + "] to registered "
                            + target + ": " + r);
                  
                    deliverToRegisteredReceiverLocked(r, (BroadcastFilter)target, false);
                }
                addBroadcastToHistoryLocked(r);
                if (DEBUG_BROADCAST_LIGHT) Slog.v(TAG, "Done with parallel broadcast ["
                        + mQueueName + "] " + r);
            }
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deliverToRegisteredReceiverLocked(r, (BroadcastFilter)target, false);看这个方法，看名字就像是发送广播的方法，这个时候就体现命名规范的作用了，我记得我最开始写代码的时候，那名字起的，过段时间自己都不知道自己写的啥。看了看这个方法，果然啊，一会再分析他，继续往下看。

deliverToRegisteredReceiverLocked(),又会调用performReceiveLocked().

  private static void performReceiveLocked(ProcessRecord app, IIntentReceiver receiver,
            Intent intent, int resultCode, String data, Bundle extras,
            boolean ordered, boolean sticky, int sendingUser) throws RemoteException {
        // Send the intent to the receiver asynchronously using one-way binder calls.
        if (app != null && app.thread != null) {
            // If we have an app thread, do the call through that so it is
            // correctly ordered with other one-way calls.
            app.thread.scheduleRegisteredReceiver(receiver, intent, resultCode,
                    data, extras, ordered, sticky, sendingUser, app.repProcState);
        } else {
            receiver.performReceive(intent, resultCode, data, extras, ordered,
                    sticky, sendingUser);
        }
    }

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之后会开始处理有序动态注册广播

 if (nextReceiver instanceof BroadcastFilter) {
                // Simple case: this is a registered receiver who gets
                // a direct call.
                BroadcastFilter filter = (BroadcastFilter)nextReceiver;
                if (DEBUG_BROADCAST)  Slog.v(TAG,
                        "Delivering ordered ["
                        + mQueueName + "] to registered "
                        + filter + ": " + r);
                deliverToRegisteredReceiverLocked(r, filter, r.ordered);
                if (r.receiver == null || !r.ordered) {
                    // The receiver has already finished, so schedule to
                    // process the next one.
                    if (DEBUG_BROADCAST) Slog.v(TAG, "Quick finishing ["
                            + mQueueName + "]: ordered="
                            + r.ordered + " receiver=" + r.receiver);
                    r.state = BroadcastRecord.IDLE;
                    scheduleBroadcastsLocked();
                }
                return;
            }
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然后会处理静态注册的广播

   ProcessRecord app = mService.getProcessRecordLocked(targetProcess,
                    info.activityInfo.applicationInfo.uid, false);
            if (app != null && app.thread != null) {
                try {
                    app.addPackage(info.activityInfo.packageName, mService.mProcessStats);
                    processCurBroadcastLocked(r, app);
                    return;
                } catch (RemoteException e) {
                    Slog.w(TAG, "Exception when sending broadcast to "
                          + r.curComponent, e);
                } catch (RuntimeException e) {
                    Log.wtf(TAG, "Failed sending broadcast to "
                            + r.curComponent + " with " + r.intent, e);
                    // If some unexpected exception happened, just skip
                    // this broadcast.  At this point we are not in the call
                    // from a client, so throwing an exception out from here
                    // will crash the entire system instead of just whoever
                    // sent the broadcast.
                    logBroadcastReceiverDiscardLocked(r);
                    finishReceiverLocked(r, r.resultCode, r.resultData,
                            r.resultExtras, r.resultAbort, false);
                    scheduleBroadcastsLocked();
                    // We need to reset the state if we failed to start the receiver.
                    r.state = BroadcastRecord.IDLE;
                    return;
                }

                // If a dead object exception was thrown -- fall through to
                // restart the application.
            }
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 private final void processCurBroadcastLocked(BroadcastRecord r,
            ProcessRecord app) throws RemoteException {
        if (DEBUG_BROADCAST)  Slog.v(TAG,
                "Process cur broadcast " + r + " for app " + app);
        if (app.thread == null) {
            throw new RemoteException();
        }
        r.receiver = app.thread.asBinder();
        r.curApp = app;
        app.curReceiver = r;
        app.forceProcessStateUpTo(ActivityManager.PROCESS_STATE_RECEIVER);
        mService.updateLruProcessLocked(app, false, null);
        mService.updateOomAdjLocked();

        // Tell the application to launch this receiver.
        r.intent.setComponent(r.curComponent);

        boolean started = false;
        try {
            if (DEBUG_BROADCAST_LIGHT) Slog.v(TAG,
                    "Delivering to component " + r.curComponent
                    + ": " + r);
            mService.ensurePackageDexOpt(r.intent.getComponent().getPackageName());
            app.thread.scheduleReceiver(new Intent(r.intent), r.curReceiver,
                    mService.compatibilityInfoForPackageLocked(r.curReceiver.applicationInfo),
                    r.resultCode, r.resultData, r.resultExtras, r.ordered, r.userId,
                    app.repProcState);
            if (DEBUG_BROADCAST)  Slog.v(TAG,
                    "Process cur broadcast " + r + " DELIVERED for app " + app);
            started = true;
        } finally {
            if (!started) {
                if (DEBUG_BROADCAST)  Slog.v(TAG,
                        "Process cur broadcast " + r + ": NOT STARTED!");
                r.receiver = null;
                r.curApp = null;
                app.curReceiver = null;
            }
        }
    }
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如果说当前进程不存在的话需要重新拉起进程，这个也就是静态注册的广播能够被死掉的进程所接收的原因。

if (DEBUG_BROADCAST)  Slog.v(TAG,
                    "Need to start app ["
                            + mQueueName + "] " + targetProcess + " for broadcast " + r);
            if ((r.curApp=mService.startProcessLocked(targetProcess,
                    info.activityInfo.applicationInfo, true,
                    r.intent.getFlags() | Intent.FLAG_FROM_BACKGROUND,
                    "broadcast", r.curComponent,
                    (r.intent.getFlags()&Intent.FLAG_RECEIVER_BOOT_UPGRADE) != 0, false, false))
                            == null) {
                // Ah, this recipient is unavailable.  Finish it if necessary,
                // and mark the broadcast record as ready for the next.
                Slog.w(TAG, "Unable to launch app "
                        + info.activityInfo.applicationInfo.packageName + "/"
                        + info.activityInfo.applicationInfo.uid + " for broadcast "
                        + r.intent + ": process is bad");
                logBroadcastReceiverDiscardLocked(r);
                finishReceiverLocked(r, r.resultCode, r.resultData,
                        r.resultExtras, r.resultAbort, false);
                scheduleBroadcastsLocked();
                r.state = BroadcastRecord.IDLE;
                return;
            }
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兜兜转转的,终于来到了最后一步，我太难了。。。。。。

//静态的
  app.thread.scheduleReceiver(new Intent(r.intent), r.curReceiver,
                    mService.compatibilityInfoForPackageLocked(r.curReceiver.applicationInfo),
                    r.resultCode, r.resultData, r.resultExtras, r.ordered, r.userId,
                    app.repProcState);
//动态的
      app.thread.scheduleRegisteredReceiver(receiver, intent, resultCode,
                    data, extras, ordered, sticky, sendingUser, app.repProcState);
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总结

兜兜转转的整整写了两天，广播其实就是注册，匹配，发送的过程。动态注册就是将相关的信息保存到AMS中，静态注册其实是在安装时，PKMS解析xml文件进行保存的。匹配其实是AMS做的主要工作，静态注册的广播需要通过PKMS进行查询匹配，动态注册的广播就保存在他自己这里呀。发送，额，也就是发送了，通过binder机制。

参考文献

Android Broadcast原理分析之registerReceiver（一）
[Android]Ams 广播发送原理（三）
Android8.0.0-r4——广播的注册、发送和接收过程