startForegroundService与startService 使用浅析

 
public class MyService extends Service {
 
    @Override
    public void onCreate() {
        super.onCreate();
    }
 
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return startCommandReturnId;
    }
 
    @Override
    public void onDestroy() {
        super.onDestroy();
    }
 
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

....// 业务启动流程结束
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && (guildInfo != null)) {
    getApp().applicationContext.startForegroundService(serviceIntent)
} else {
    getApp().applicationContext.startService(serviceIntent)
       }

// Service类中
public int onStartCommand(Intent intent, int flags, int startId) {
   ....
mAudioNotification = createAudioNotification(); //创建通知栏展示内容
startForeground(NID, mAudioNotification); // 展示服务通知
   ....
}

Context.startForegroundService() did not then call Service.startForeground(): ServiceRecord

@Override
    public ComponentName startService(Intent service) {
        warnIfCallingFromSystemProcess();
        return startServiceCommon(service, false, mUser);
    }
 
    @Override
    public ComponentName startForegroundService(Intent service) {
        warnIfCallingFromSystemProcess();
        return startServiceCommon(service, true, mUser);
    }
    private ComponentName startServiceCommon(Intent service, boolean requireForeground, 
       UserHandle user）

private ComponentName startServiceCommon(Intent service, boolean requireForeground,
            UserHandle user) {
        try {
            validateServiceIntent(service);
            service.prepareToLeaveProcess(this);
            ComponentName cn = ActivityManager.getService().startService(
                    mMainThread.getApplicationThread(), service,
                    service.resolveTypeIfNeeded(getContentResolver()), requireForeground,
                    getOpPackageName(), getAttributionTag(), user.getIdentifier());
            if (cn != null) {
                // 异常匹配
                if (cn.getPackageName().equals("!")) {
                    throw new SecurityException(
                            "Not allowed to start service " + service
                            + " without permission " + cn.getClassName());
                } else if (cn.getPackageName().equals("!!")) {
                    throw new SecurityException(
                            "Unable to start service " + service
                            + ": " + cn.getClassName());
                } else if (cn.getPackageName().equals("?")) {
                    throw ServiceStartNotAllowedException.newInstance(requireForeground,
                            "Not allowed to start service " + service + ": " + cn.getClassName());
                }
            }
           ....
            return cn;
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }

if (forcedStandby || (!r.startRequested && !fgRequired)) {
            // 调用startService，(!r.startRequested && !fgRequired) 条件为true
            final int allowed = mAm.getAppStartModeLOSP(r.appInfo.uid, r.packageName,
                    r.appInfo.targetSdkVersion, callingPid, false, false, forcedStandby);
            if (allowed != ActivityManager.APP_START_MODE_NORMAL) {
                if (allowed == ActivityManager.APP_START_MODE_DELAYED || forceSilentAbort) {
                    return null;
                }
                if (forcedStandby) {
                    if (fgRequired) {
                        return null;
                    }
                }
                UidRecord uidRec = mAm.mProcessList.getUidRecordLOSP(r.appInfo.uid);
                return new ComponentName("?", "app is in background uid " + uidRec);
            }
        }

// Unified app-op and target sdk check
    @GuardedBy(anyOf = {"this", "mProcLock"})
    int appRestrictedInBackgroundLOSP(int uid, String packageName, int packageTargetSdk) {
        // 安卓8限制
        if (packageTargetSdk >= Build.VERSION_CODES.O) {
            if (DEBUG_BACKGROUND_CHECK) {
                Slog.i(TAG, "App " + uid + "/" + packageName + " targets O+, restricted");
            }
            return ActivityManager.APP_START_MODE_DELAYED_RIGID;
        }
        .....
    }

private final void sendServiceArgsLocked(ServiceRecord r, boolean execInFg,
        boolean oomAdjusted) throws TransactionTooLargeException {
    ...
    ArrayList<ServiceStartArgs> args = new ArrayList<>();
    while (r.pendingStarts.size() > 0) {
        ServiceRecord.StartItem si = r.pendingStarts.remove(0);
        ...
        if (r.fgRequired && !r.fgWaiting) {
            if (!r.isForeground) {
            <!--监听是否5S内startForeground-->
                scheduleServiceForegroundTransitionTimeoutLocked(r);
            } ...
       try {
        r.app.thread.scheduleServiceArgs(r, slice);
    }

void scheduleServiceForegroundTransitionTimeoutLocked(ServiceRecord r) {
        if (r.app.mServices.numberOfExecutingServices() == 0 || r.app.getThread() == null) {
            return;
        }
        Message msg = mAm.mHandler.obtainMessage(
                ActivityManagerService.SERVICE_FOREGROUND_TIMEOUT_MSG);
        msg.obj = r;
        r.fgWaiting = true;
        mAm.mHandler.sendMessageDelayed(msg, mAm.mConstants.mServiceStartForegroundTimeoutMs);
    }
/**
     * How long the Context.startForegroundService() grace period is to get around to
     * calling Service.startForeground() before we generate ANR.
     */
    volatile int mServiceStartForegroundTimeoutMs = DEFAULT_SERVICE_START_FOREGROUND_TIMEOUT_MS;

 修改 r.fgWaiting = true启动任务延迟TimeoutMs后发送 SERVICE_FOREGROUND_TIMEOUT_MSG

// handler处理 SERVICE_FOREGROUND_TIMEOUT_MSG
void serviceForegroundTimeout(ServiceRecord r) {
        ProcessRecord app;
        synchronized (mAm) {
            if (!r.fgRequired || !r.fgWaiting || r.destroying) {
                return;
            }
            app = r.app;
            if (app != null && app.isDebugging()) {
                // The app's being debugged; let it ride
                return;
            }
            if (DEBUG_BACKGROUND_CHECK) {
                Slog.i(TAG, "Service foreground-required timeout for " + r);
            }
            r.fgWaiting = false;
            stopServiceLocked(r, false);
        }
        if (app != null) {
// 就是我们之前遇到的异常
            final String annotation = "Context.startForegroundService() did not then call "+ "Service.startForeground(): " + r;
            Message msg = mAm.mHandler.obtainMessage(ActivityManagerService.SERVICE_FOREGROUND_TIMEOUT_ANR_MSG);
            SomeArgs args = SomeArgs.obtain();
            args.arg1 = app;
            args.arg2 = annotation;
            msg.obj = args;
            mAm.mHandler.sendMessageDelayed(msg,
                    mAm.mConstants.mServiceStartForegroundAnrDelayMs);
        }
    }

private final void bringDownServiceLocked(ServiceRecord r) {
        ...
        if (r.fgRequired) {
        r.fgRequired = false;
        r.fgWaiting = false;
        mAm.mAppOpsService.finishOperation(AppOpsManager.getToken(mAm.mAppOpsService),
                AppOpsManager.OP_START_FOREGROUND, r.appInfo.uid, r.packageName);
        mAm.mHandler.removeMessages(
                ActivityManagerService.SERVICE_FOREGROUND_TIMEOUT_MSG, r);
        if (r.app != null) {
            Message msg = mAm.mHandler.obtainMessage(
                    ActivityManagerService.SERVICE_FOREGROUND_CRASH_MSG);
            msg.obj = r.app;
            msg.getData().putCharSequence(
                ActivityManagerService.SERVICE_RECORD_KEY, r.toString());
            mAm.mHandler.sendMessage(msg);
        }
    }