Question

我编写了自己的MediaPlayer类来播放特定路径中的文件并播放assets文件夹中的文件。这是班级：

public class CMediaPlayer extends MediaPlayer{

public void play(String audioPath){

   this.setOnCompletionListener(new OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mp) {
            mp.release();
        }
    });

    File f = new File(audioPath);
    if(f.exists()){
        try{
            FileInputStream fis = new FileInputStream(f);
            FileDescriptor fileD = fis.getFD();
            this.setDataSource(fileD);
            this.prepare();

        }catch(IOException e){

        }
       this.start();
}
}

    public void play(AssetFileDescriptor descriptor){

        this.setOnCompletionListener(new OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
               mp.release();
            }
        });
        try {
            this.setDataSource(descriptor.getFileDescriptor(), descriptor.getStartOffset(), descriptor.getLength());
            descriptor.close();
            this.prepare();
        }catch (IOException e){

        }
        this.start();
    }

}

我想在活动中播放该类的几种声音。这是我的代码：

public class playGame extends Activity {

//a lot of variables

    CMediaPlayer mediaPlayer; //declare my mediaplayer

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK ) {
            //release??????
            Intent myIntent = new Intent(getBaseContext(), startView.class);
            startActivity(myIntent);
        }
        return super.onKeyDown(keyCode, event);
    }

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_play_question2);

        mediaPlayer = new CMediaPlayer(); //define my mediaplayer

       //stuff
    }

    //more variables

    public void playQuestion(File question){

        //stuff

        TextView myTextView = (TextView) findViewById(R.id.textViewQuestion);
        //stuff
        myTextView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            mediaPlayer.play(pathSoundQuestion); //play sound when clicked
            }
        });

    //stuff

        myImageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               mediaPlayer.play(pathSoundQuestion); //play sound when clicked
            }
        });

        //stuff
        mediaPlayer.play(pathSoundQuestion); //plays sound immediatly, first played sound (works fine)

        //button1
        Button myButton = (Button) findViewById(R.id.button1);
        //stuff
        myButton.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(lastClickedButton == v){
                   //stuff
                    return;
                }
                //stuff
                mediaPlayer.play(pathAudio1); //play sound when clicked (error)
            }
        });

        //button2
        myButton = (Button) findViewById(R.id.button2);
       //stuff
        myButton.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(lastClickedButton == v){
                    //stuff
                    return;
                }
                //stuff
                mediaPlayer.play(pathAudio2); //play sound, same problem
            }
        });

       //goes on like this some more times...
    }

    public void logIn(View v, String right){
        //stuff

        if(right.equals("true")){
           //stuff
            try {
                AssetFileDescriptor descriptor = getAssets().openFd("Right");
                mediaPlayer.play(descriptor); //play sound from assets
                Intent myIntent = new Intent(getApplication(), playGame.class);
                startActivity(myIntent);
            }catch (IOException e){
            }
        }else{
          //stuff
            try {
                AssetFileDescriptor descriptor = getAssets().openFd("Wrong");
                mediaPlayer.play(descriptor); //play sound from assets
                Intent myIntent = new Intent(getApplication(), playGame.class);
                startActivity(myIntent);
            }catch (IOException e){
            }
        }
    }
}

应用播放我的代码中的评论中提到的第一个声音。当我点击一个应该开始另一个声音的按钮时，我收到以下错误：

03-16 23:07:38.478  13646-13646/com.example.cello.myownquiz E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.IllegalStateException
            at android.media.MediaPlayer.setDataSource(Native Method)
            at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1005)

我的MediaPlayer课程是否正常，或者我是否遗漏某些内容取决于州？这个班级是唯一可以发布电话的地方，还是我必须把它放在我的活动中？

有人看到我的错吗？ mediaPlayer的这个问题花了我一整天的时间，希望你能帮助我...

Answer 1

将mp.release();更改为mp.reset();

public void reset（）

将MediaPlayer重置为未初始化状态。调用此方法后，您必须通过设置数据源并调用prepare（）来重新初始化它。

public void release（）

释放与此MediaPlayer对象关联的资源。完成使用MediaPlayer后调用此方法被认为是一种好习惯。特别是，每当应用程序的Activity暂停（调用其onPause（）方法）或停止（调用其onStop（）方法）时，应该调用此方法来释放MediaPlayer对象，除非应用程序特别需要保持对象。除了持有不必要的资源（例如内存和编解码器实例）之外，如果不再需要MediaPlayer对象，则无法立即调用此方法也可能导致移动设备的电池持续消耗，如果没有则会导致其他应用程序的播放失败设备支持相同编解码器的多个实例。即使支持相同编解码器的多个实例，当同时使用不必要的多个实例时，也可能预期性能下降。

您需要保留对象。

你可以用一种简单的方式做到这一点

        MediaPlayer mediaPlayer = new MediaPlayer();
        mediaPlayer.setDataSource(context, ringtone);
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MEDIA);
        mediaPlayer.prepare();
        mediaPlayer.start();

Answer 2

我也有这个问题，但我用过：

public void play(String name){
    try {
        AssetFileDescriptor afd = getAssets().openFd(name);
        if(myPlayer == null){
            myPlayer = new MediaPlayer();
        }
        myPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
        myPlayer.prepare();
        myPlayer.start();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

并停止：

public void stopPlayer(){
    if(myPlayer!= null && myPlayer.isPlaying()){
        myPlayer.stop();
        myPlayer = null;
    }else{
        myPlayer = null;
    }
}

Android MediaPlayer - setDataSource和Release - IllegalStateException

2 个答案: