Question

我在片段中创建了一个媒体播放器。我把它初始化为：

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Main.mp = new MediaPlayer();

    }

首先，当按下这首歌还在播放时我遇到了问题。为什么添加以下代码： -

public void onPause() {
        super.onPause();
        if (Main.prepared && !error) {
            if (Main.mp.isPlaying()) {
                Main.mp.stop();
            }
        }
    }

public void onBackPressed() {

        if (getFragmentManager().getBackStackEntryCount() > 0) {
            getFragmentManager().popBackStack();
        }
        // super.onBackPressed();
    }

现在当我按下它时会停止媒体播放器。但是，当我按下那首歌并按下播放按钮时，它会再次崩溃。我得到这个错误：

08-14 12:07:16.650: E/AndroidRuntime(9913): FATAL EXCEPTION: main
08-14 12:07:16.650: E/AndroidRuntime(9913): java.lang.IllegalStateException
08-14 12:07:16.650: E/AndroidRuntime(9913):     at android.media.MediaPlayer.isPlaying(Native Method)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at com.fragment.StreamFragment$7.run(StreamFragment.java:290)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at android.os.Handler.handleCallback(Handler.java:615)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at android.os.Looper.loop(Looper.java:213)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at android.app.ActivityThread.main(ActivityThread.java:4787)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at java.lang.reflect.Method.invokeNative(Native Method)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at java.lang.reflect.Method.invoke(Method.java:511)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
08-14 12:07:16.650: E/AndroidRuntime(9913):     at dalvik.system.NativeStart.main(Native Method)

编写的代码（StreamFragment.java:290）是：

// set seeker to follow media player
                    handler = new Handler();
                    r = new Runnable() {
                        @Override
                        public void run() {
                            if (Main.prepared) {
                                if (Main.mp.isPlaying() ) {
                                    seeker.setProgress(Main.mp
                                            .getCurrentPosition());
                                }
                            }
                            seeker.postDelayed(r, 200);
                        }
                    };
                    handler.postDelayed(r, 1000);

Answer 1

你必须在片段中按下键，检查键码。 onBackPress（）方法可以在Activity中使用 - 它是片段的逻辑父级。

试试这个：

frag.getView().setFocusableInTouchMode(true);
frag.getView().setOnKeyListener( new OnKeyListener(){
    @Override
    public boolean onKey( View v, int keyCode, KeyEvent event ){
        if( keyCode == KeyEvent.KEYCODE_BACK ){

               // your media player code

            if (getFragmentManager().getBackStackEntryCount() > 0)
               {
                getFragmentManager().popBackStack();
                 }
            return true;
        }
        return false;
    }
} );

Answer 2

试试这个

MediaPlayer mediaPlayer;
Button buttonPlayPause, buttonQuit;
TextView textState;

private int stateMediaPlayer;
private final int stateMP_NotStarter = 0;
private final int stateMP_Playing = 1;
private final int stateMP_Pausing = 2;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    buttonPlayPause = (Button)findViewById(R.id.playpause);
    buttonQuit = (Button)findViewById(R.id.quit);
    textState = (TextView)findViewById(R.id.state);

    buttonPlayPause.setOnClickListener(buttonPlayPauseOnClickListener);
    buttonQuit.setOnClickListener(buttonQuitOnClickListener);

    initMediaPlayer();

}

private void initMediaPlayer()
{
 mediaPlayer = new  MediaPlayer();
    mediaPlayer = MediaPlayer.create(AndroidMediaPlayer.this, R.raw.music);
    stateMediaPlayer = stateMP_NotStarter;
    textState.setText("- IDLE -");
}

Button.OnClickListener buttonPlayPauseOnClickListener
 = new Button.OnClickListener(){

 @Override
 public void onClick(View v) {
  // TODO Auto-generated method stub
  switch(stateMediaPlayer){
  case stateMP_NotStarter:
   mediaPlayer.start();
   buttonPlayPause.setText("Pause");
   textState.setText("- PLAYING -");
   stateMediaPlayer = stateMP_Playing;
   break;
  case stateMP_Playing:
   mediaPlayer.pause();
   buttonPlayPause.setText("Play");
   textState.setText("- PAUSING -");
   stateMediaPlayer = stateMP_Pausing;
   break;
  case stateMP_Pausing:
   mediaPlayer.start();
   buttonPlayPause.setText("Pause");
   textState.setText("- PLAYING -");
   stateMediaPlayer = stateMP_Playing;
   break;
  }

 }
};

Button.OnClickListener buttonQuitOnClickListener
= new Button.OnClickListener(){

@Override
public void onClick(View v) {
 // TODO Auto-generated method stub
 mediaPlayer.stop();
 mediaPlayer.release();
 finish();
}
};
}

在Main.mp.isPlaying（）中获取java.lang.IllegalStateException

2 个答案: