Question

我在我的活动背景中使用音乐。但是当我试图取消它时它不起作用。音乐一直在持续运行，直到它完成。以下是代码：

public class xx extends Activity 
{ BackgroundSound mBackgroundSound = new BackgroundSound();

  @Override
protected void onCreate(Bundle savedInstanceState) 
{ ....
     }

  @Override
protected void onResume() 
{
    super.onResume();
    mBackgroundSound.execute();
}

@Override
protected  void onPause()
  {
      super.onPause();
      mBackgroundSound.cancel(true);
      }

和选项菜单选择：

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
         mBackgroundSound.cancel(true);
                NavUtils.navigateUpFromSameTask(this);

                return true;
    case R.id.menu_Add:
        { mBackgroundSound.cancel(true);
            Intent intent = new Intent(xx.this,yy.class);
                intent.putExtra("flag", "add");
                intent.putExtra("AddObj", "mm");

            startActivity(intent);
            break;
        }
    case R.id.menu_list_quote:
        {
            mBackgroundSound.cancel(true);
            Intent intent = new   Intent(xx.this,zz.class);
                intent.putExtra("Obj", "nn");

            startActivity(intent);

            break;
        }   


    }
    //return true;
    return super.onOptionsItemSelected(item);
}

和asynTask：

 public class BackgroundSound extends AsyncTask<Void, Void, Void> {
     @Override
     protected Void doInBackground(Void... params) {
         try
         {
             while( !isCancelled())
             {

            // FileDescriptor afd = openFd("cock_alarm.mp3");
             MediaPlayer player = new MediaPlayer();
             player.setDataSource(_musicFilePath);
             player.prepare();
             //player.setLooping(true); // Set looping 
             player.setVolume(100,100); 
             player.start(); 
           //  if(isCancelled())
            //   player.stop();
             }

         }
         catch(Exception exp)
         {
             exp.printStackTrace();
         }
         return null;
      }
        }

另外，尝试使用for循环：

  for(int i=0;i<100 && !isCancelled();i++)

并在asyncTask的try块中尝试了这个：

if(isCancelled())
 player.stop();

我将如何解决它？

Answer 1

为什么不创建MediaPlayer，而不是创建AsyncTask，而是从您的活动中启动它？

MediaPlayer内置了自己的线程逻辑。您不需要创建一个线程来管理媒体播放器。您可以在此处阅读更多内容：http://developer.android.com/guide/topics/media/mediaplayer.html

在您的活动中，您可以执行以下操作：

private MediaPlayer mMediaPlayer;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Initalize the media player
    mMediaPlayer = ... however you are initializing it ...;

    // Set the listener so the media player can tell you when it is finished preparing
    mMediaPlayer.setOnPreparedListener(this);

    // Prepare the MediaPlayer asynchronously so that the UI thread does not lock up
    mMediaPlayer.prepareAsync();
}

// You need to listen for when the Media Player is finished preparing and is ready
public void onPrepared(MediaPlayer player) {
    // Start the player
    player.start();
}

然后，只要您需要停止播放器，只需拨打

即可

mMediaPlayer.stop();

Answer 2

正如，vogella在他的网站上解释的那样： “AsyncTask不会自动处理配置更改，即如果重新创建活动，程序员必须在编码时处理它。

一个常见的解决方案是在保留的无头片段中声明AsyncTask。“

查找全文： http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html#androidbackground

使用asyncTask播放的音乐不会因使用取消而停止

2 个答案: