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Android换肤实现原理_getresourceentryname getidentifier

作者：繁依Fanyi0 | 2024-02-15 21:00:01

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getresourceentryname getidentifier

流程分析

1.创建skip.apk,里面只有要修改的资源文件，没有代码
2.将skip.apk放在data/data目录下
3.通过原apk中的资源id获取到资源的name和type,然后通过mSkinResources.getIdentifier获取到皮肤包中的资源（mSkinResources是skip.apk资源包中获取的Resources,下面会讲怎么获取skip.apk中的资源）

  1. /**
  2.      * 1.通过原始app中的resId(R.color.XX)获取到自己的 名字
  3.      * 2.根据名字和类型获取皮肤包中的ID
  4.      */
  5.     public int getIdentifier(int resId){
  6.         if(isDefaultSkin){
  7.             return resId;
  8.         }
  9.         String resName=mAppResources.getResourceEntryName(resId);
  10.         String resType=mAppResources.getResourceTypeName(resId);
  11.         int skinId=mSkinResources.getIdentifier(resName,resType,mSkinPkgName);
  12.         return skinId;
  13.     }

4.对view更换新的资源 

1.Resource是怎么加载进内存的

当我们的app进程创建出来的时候，回执行我们app的入口函数ActivityThread.main()方法

  1. //创建ActivityThread
  2.  ActivityThread thread = new ActivityThread();
  3.  thread.attach(true, 0);
  4. //查看attach
  5. final IActivityManager mgr = ActivityManager.getService();
  6.       //通过AMS的代理对象，会执行AMS的attachApplication()
  7.       mgr.attachApplication(mAppThread, startSeq);
  8. //来到AMS中,通过ApplicationThread的代理类，执行thread.bindApplication
  9. //查看ApplicationThread的bindApplication()方法,通过handler执行handleBindApplication()
  10. //handleBindApplication()中会makeApplication(data.restrictedBackupMode, null);
  11. //makeApplication 中ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);
  1.     static ContextImpl createAppContext(ActivityThread mainThread, LoadedApk packageInfo) {
  2.         if (packageInfo == null) throw new IllegalArgumentException("packageInfo");
  3.         ContextImpl context = new ContextImpl(null, mainThread, packageInfo, null, null, null, 0,
  4.                 null);
  5.         //获取Resources
  6.         context.setResources(packageInfo.getResources());
  7.         return context;
  8.     }

 

  1. //LoadApk
  2.     public Resources getResources() {
  3.         if (mResources == null) {
  4.             final String[] splitPaths;
  5.             try {
  6.                 splitPaths = getSplitPaths(null);
  7.             } catch (NameNotFoundException e) {
  8.                 // This should never fail.
  9.                 throw new AssertionError("null split not found");
  10.             }
  11.  
  12.             mResources = ResourcesManager.getInstance().getResources(null, mResDir,
  13.                     splitPaths, mOverlayDirs, mApplicationInfo.sharedLibraryFiles,
  14.                     Display.DEFAULT_DISPLAY, null, getCompatibilityInfo(),
  15.                     getClassLoader());
  16.         }
  17.         return mResources;
  18.     }

 

  1.     private @Nullable Resources getOrCreateResources(@Nullable IBinder activityToken,
  2.             @NonNull ResourcesKey key, @NonNull ClassLoader classLoader) {
  3.         ...
  4.             ResourcesImpl resourcesImpl = createResourcesImpl(key);
  5.             if (resourcesImpl == null) {
  6.                 return null;
  7.             }
  8.  
  9.             // Add this ResourcesImpl to the cache.
  10.             mResourceImpls.put(key, new WeakReference<>(resourcesImpl));
  11.  
  12.             final Resources resources;
  13.             if (activityToken != null) {
  14.                 resources = getOrCreateResourcesForActivityLocked(activityToken, classLoader,
  15.                         resourcesImpl, key.mCompatInfo);
  16.             } else {
  17.                 resources = getOrCreateResourcesLocked(classLoader, resourcesImpl, key.mCompatInfo);
  18.             }
  19.             return resources;
  20.         }
  21.     }

重点重点，创建我们的Resource 

  1.     private @Nullable ResourcesImpl createResourcesImpl(@NonNull ResourcesKey key) {
  2.         final DisplayAdjustments daj = new DisplayAdjustments(key.mOverrideConfiguration);
  3.         daj.setCompatibilityInfo(key.mCompatInfo);
  4.         //关键代码
  5.  
  6.         final AssetManager assets = createAssetManager(key);
  7.         if (assets == null) {
  8.             return null;
  9.         }
  10.  
  11.         final DisplayMetrics dm = getDisplayMetrics(key.mDisplayId, daj);
  12.         final Configuration config = generateConfig(key, dm);
  13.         final ResourcesImpl impl = new ResourcesImpl(assets, dm, config, daj);
  14.  
  15.         if (DEBUG) {
  16.             Slog.d(TAG, "- creating impl=" + impl + " with key: " + key);
  17.         }
  18.         return impl;
  19.     }

 到这里，我们将新的资源加载进去了，demo代码

  1.  //宿主app的 resources;
  2.                 Resources appResource = mContext.getResources();
  3. //
  4.                 //反射创建AssetManager 与 Resource
  5.                 AssetManager assetManager = AssetManager.class.newInstance();
  6.                 //资源路径设置 目录或压缩包
  7.                 Method addAssetPath = assetManager.getClass().getMethod("addAssetPath",
  8.                         String.class);
  9.                 addAssetPath.invoke(assetManager, skinPath);
  10.  
  11.                 //根据当前的设备显示器信息 与 配置(横竖屏、语言等) 创建Resources
  12.                 Resources skinResource = new Resources(assetManager, appResource.getDisplayMetrics
  13.                         (), appResource.getConfiguration());

1.从setContentView()流程查看View是怎么创建出来的

activity中setContentView(layoutResID);
调用到getWindow().setContentView(layoutResID);Window的实现类是PhoneWindow
  1. public void setContentView(int layoutResID) {
  2.         // Note: FEATURE_CONTENT_TRANSITIONS may be set in the process of installing the window
  3.         // decor, when theme attributes and the like are crystalized. Do not check the feature
  4.         // before this happens.
  5.         if (mContentParent == null) {
  6.             installDecor();
  7.         } else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
  8.             mContentParent.removeAllViews();
  9.         }
  10.  
  11.         if (hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
  12.             final Scene newScene = Scene.getSceneForLayout(mContentParent, layoutResID,
  13.                     getContext());
  14.             transitionTo(newScene);
  15.         } else {
  16.             //重点看inflate工程
  17.             mLayoutInflater.inflate(layoutResID, mContentParent);
  18.         }
  19.         mContentParent.requestApplyInsets();
  20.         final Callback cb = getCallback();
  21.         if (cb != null && !isDestroyed()) {
  22.             cb.onContentChanged();
  23.         }
  24.         mContentParentExplicitlySet = true;
  25.     }

一直跟进去，到LayoutInflater中

  1.     public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
  2.         synchronized (mConstructorArgs) {
  3.            ...
  4.                     // Temp is the root view that was found in the xml
  5.                     //创建view
  6.                     final View temp = createViewFromTag(root, name, inflaterContext, attrs);
  7.  
  8.                     ... 
  9.         }
  10.     }
  1.     View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
  2.             boolean ignoreThemeAttr) {
  3.  
  4.         ...
  5.         try {
  6.             View view;
  7.             //重点来了
  8.             //默认mFactory2为空，这个是Google默认给我们留的一个入口，我们重写mFactory2后就可以修改view, 换肤我们就从这儿开始，LayoutInflaterCompat.setFactory2(layoutInflater, skinLayoutInflaterFactory);
  9.             if (mFactory2 != null) {
  10.                 view = mFactory2.onCreateView(parent, name, context, attrs);
  11.             } else if (mFactory != null) {
  12.                 //默认是用的mFactory
  13.                 view = mFactory.onCreateView(name, context, attrs);
  14.             } else {
  15.                 view = null;
  16.             }
  17.  
  18.             if (view == null && mPrivateFactory != null) {
  19.                 view = mPrivateFactory.onCreateView(parent, name, context, attrs);
  20.             }
  21.  
  22.             if (view == null) {
  23.                 final Object lastContext = mConstructorArgs[0];
  24.                 mConstructorArgs[0] = context;
  25.                 try {
  26.                     //上面创建失败，创建view的工程，我们会在mFactory2中抄袭这块儿代码
  27.                     //普通view
  28.                     if (-1 == name.indexOf('.')) {
  29.                         view = onCreateView(parent, name, attrs);
  30.                     } else {
  31.                     //a.b.c.View一般是自定义view
  32.                         view = createView(name, null, attrs);
  33.                     }
  34.                 } finally {
  35.                     mConstructorArgs[0] = lastContext;
  36.                 }
  37.             }
  38.  
  39.             return view;
  40.         }
  41. ...
  42.     }

2.分析如何重写Factory2中创建view的方法

  1. public interface Factory2 extends Factory {
  2.         public View onCreateView(View parent, String name, Context context, AttributeSet attrs);
  3.     }

2.1创建SkinLayoutInflaterFactory.java实现Factory2接口，重写onCreateView()创建我们的View
抄写LayoutInflater中创建view的方式
 

  1. public class SkinLayoutInflaterFactory implements LayoutInflater.Factory2 {
  2.  
  3.     private static final String[] mClassPrefixList = {
  4.             "android.widget.",
  5.             "android.webkit.",
  6.             "android.app.",
  7.             "android.view."
  8.     };
  9.  
  10.     //记录对应VIEW的构造函数
  11.     private static final Class<?>[] mConstructorSignature = new Class[] {
  12.             Context.class, AttributeSet.class};
  13.  
  14.     private static final HashMap<String, Constructor<? extends View>> mConstructorMap =
  15.             new HashMap<String, Constructor<? extends View>>();
  16.  
  17.     
  18.     private Activity activity;
  19.  
  20.  
  21.     @Override
  22.     public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
  23.         //换肤就是在需要时候替换 View的属性(src、background等)
  24.         //所以这里创建 View,从而修改View属性
  25.         View view = createSDKView(name, context, attrs);
  26.         if (null == view) {
  27.             view = createView(name, context, attrs);
  28.         }
  29. //拿到view,就可以对其更换资源
  30.        
  31.         return view;
  32.     }
  33.  
  34.  
  35.     private View createSDKView(String name, Context context, AttributeSet
  36.             attrs) {
  37.         //如果包含 . 则不是SDK中的view 可能是自定义view包括support库中的View
  38.         if (-1 != name.indexOf('.')) {
  39.             return null;
  40.         }
  41.         //不包含就要在解析的 节点 name前，拼上： android.widget. 等尝试去反射
  42.         for (int i = 0; i < mClassPrefixList.length; i++) {
  43.             View view = createView(mClassPrefixList[i] + name, context, attrs);
  44.             if(view!=null){
  45.                 return view;
  46.             }
  47.         }
  48.         return null;
  49.     }
  50.  
  51.     private View createView(String name, Context context, AttributeSet
  52.             attrs) {
  53.         Constructor<? extends View> constructor = findConstructor(context, name);
  54.         try {
  55.             return constructor.newInstance(context, attrs);
  56.         } catch (Exception e) {
  57.         }
  58.         return null;
  59.     }
  60.  
  61.  
  62.  
  63.     private Constructor<? extends View> findConstructor(Context context, String name) {
  64.         Constructor<? extends View> constructor = mConstructorMap.get(name);
  65.         if (constructor == null) {
  66.             try {
  67.                 Class<? extends View> clazz = context.getClassLoader().loadClass
  68.                         (name).asSubclass(View.class);
  69.                 constructor = clazz.getConstructor(mConstructorSignature);
  70.                 mConstructorMap.put(name, constructor);
  71.             } catch (Exception e) {
  72.             }
  73.         }
  74.         return constructor;
  75.     }
  76.  
  77.  
  78.  
  79.  
  80.     @Override
  81.     public View onCreateView(String name, Context context, AttributeSet attrs) {
  82.         return null;
  83.     }
  84.  
  85. }

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