像 RemoteView 一样加载其他应用的资源Load another application's resource

Load another application's resource like RemoteView do, just for fun!

声明：

通过包名和资源名即可加载到其他应用的资源，仅用于学习RemoteView远程加载布局，复杂布局下存在很多兼容性问题。

使用步骤:

1.根据包名创建可以加载到其他应用资源的Context

InflaterContext inflaterContext = new InflaterContext(this, "pw.qlm.otherapp");

2.根据上面Context创建LayoutInflater

LayoutInflater layoutInflater = LayoutInflater.from(inflaterContext);

3.获取其他应用的资源id

int layoutId = inflaterContext.getResources().getIdentifier("activity_main", "layout", inflaterContext.getPackageName());

4.根据资源id加载布局

View view = layoutInflater.inflate(layoutId, (ViewGroup) getWindow().getDecorView(), false);

原理：

public InflaterContext(Context base, String packageName) {
      super(base);
      //关键1.根据包名创建可以读取对方资源的Context
      contextForResources = ApplicationUtil.createApplicationContext(base, packageName);
      //关键2.使用该ContextWrapper克隆LayoutInflater
      inflater = LayoutInflater.from(base).cloneInContext(this);
      //关键3.若布局中用到了自定义View，需要使用该ClassLoader
      mClassLoader = new DexClassLoader(ApplicationUtil.getApkPath(contextForResources), getDir("dex", 0).getAbsolutePath(), getDir("so", 0).getAbsolutePath(), super.getClassLoader());
  }

参考RemoteView.apply()方法：

   public View apply(Context context, ViewGroup parent, OnClickHandler handler) {
      RemoteViews rvToApply = getRemoteViewsToApply(context);

      View result;
      // RemoteViews may be built by an application installed in another
      // user. So build a context that loads resources from that user but
      // still returns the current users userId so settings like data / time formats
      // are loaded without requiring cross user persmissions.
      final Context contextForResources = getContextForResources(context);
      Context inflationContext = new ContextWrapper(context) {
          @Override
          public Resources getResources() {
              return contextForResources.getResources();
          }
          @Override
          public Resources.Theme getTheme() {
              return contextForResources.getTheme();
          }
          @Override
          public String getPackageName() {
              return contextForResources.getPackageName();
          }
      };

      LayoutInflater inflater = (LayoutInflater)
              context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

      // Clone inflater so we load resources from correct context and
      // we don't add a filter to the static version returned by getSystemService.
      inflater = inflater.cloneInContext(inflationContext);
      inflater.setFilter(this);
      result = inflater.inflate(rvToApply.getLayoutId(), parent, false);

      rvToApply.performApply(result, parent, handler);

      return result;
  }