如题：谷歌自身的bug，VideoView持有ActivityContext引用，导致内存泄漏。

解决方法：

1.  xml中定义容器【如果在xml定义VideoView，那么VideoView持有的是ActivityContext】

        <RelativeLayout
            android:id="@+id/video_view_container"
            android:layout_width="match_parent"
            android:layout_height="202dp"
            android:layout_alignParentLeft="true"
            android:layout_alignParentRight="true"/>

2. activity 或 fragment中，通过容器加载VideoView

    if (mVideoViewContainer != null) {
      mVideoViewContainer.removeAllViews();
    }
    mVideoViewContainer = view.findViewById(R.id.video_view_container);
    mVideoView = new VideoView(mContext.getApplicationContext());
    mVideoViewContainer.addView(mVideoView);

3. 界面转后台或退出时，资源释放：

  @Override
  public void onDestroyView() {
    super.onDestroyView();
    mVideoView.stopPlayback();
    mVideoView.setOnCompletionListener(null);
    mVideoView.setOnPreparedListener(null);
  }

  @Override
  public void onDestroy() {
    super.onDestroy();
    mVideoViewContainer.removeAllViews();
    mVideoView = null;
  }