//匿名內(nèi)部類  
  Handler handler=new Handler(){
    @Override
    public void handleMessage(Message msg) {
      super.handleMessage(msg);
    }
  };

  //非靜態(tài)內(nèi)部類
  protected class AppHandler extends Handler {

    @Override
    public void handleMessage(Message msg) {
      switch (msg.what) {
        // TODO: 2019/4/30 
      }
    }
  }

  // 清空消息隊列，移除對外部類的引用
  @Override
  protected void onDestroy() {
    super.onDestroy();
    mHandler.removeCallbacksAndMessages(null);

  }

 
  //Handler源碼中removeCallbacksAndMessages()注釋含義
  /**
   * Remove any pending posts of callbacks and sent messages whose
   * <var>obj</var> is <var>token</var>. If <var>token</var> is null,
   * all callbacks and messages will be removed.
   */
  public final void removeCallbacksAndMessages(Object token) {
    mQueue.removeCallbacksAndMessages(this, token);
  }

  private static class AppHandler extends Handler {
    //弱引用，在垃圾回收時，被回收
    WeakReference<Activity> activity;

    AppHandler(Activity activity){
      this.activity=new WeakReference<Activity>(activity);
    }

    public void handleMessage(Message message){
      switch (message.what){
        //todo
      }
    }
  }