Question

大家好我想制作Mp3播放器和firebase存储上的歌曲。我能够第一次运行这首歌时，我改变了歌曲应用程序很遗憾地停止并给我这个错误

07-29 23:24:17.359 23466-23466/com.example.daniyal.audioplayer E/AndroidRuntime: FATAL EXCEPTION: main
                                                                             Process: com.example.daniyal.audioplayer, PID: 23466
                                                                             java.lang.IllegalStateException
                                                                                 at android.media.MediaPlayer.nativeSetDataSource(Native Method)
                                                                                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1071)
                                                                                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1032)
                                                                                 at com.example.daniyal.audioplayer.MainActivity$4.onSuccess(MainActivity.java:82)
                                                                                 at com.example.daniyal.audioplayer.MainActivity$4.onSuccess(MainActivity.java:76)
                                                                                 at com.google.android.gms.tasks.zzj.run(Unknown Source)
                                                                                 at android.os.Handler.handleCallback(Handler.java:739)
                                                                                 at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                 at android.os.Looper.loop(Looper.java:135)
                                                                                 at android.app.ActivityThread.main(ActivityThread.java:5343)
                                                                                 at java.lang.reflect.Method.invoke(Native Method)
                                                                                 at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
                                                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)

我的代码在这里：

 MediaPlayer mediaPlayer;
FirebaseStorage firebaseStorage;
Button btn1 , btn2;
String jai = "https://firebasestorage.googleapis.com/v0/b/audioplayer-49893.appspot.com/o/jai.mp3?alt=media&token=f315beb6-83ea-44f0-9beb-91d5108d9baa";
String tose = "https://firebasestorage.googleapis.com/v0/b/audioplayer-49893.appspot.com/o/tose.mp3?alt=media&token=4b3d9449-ff26-4fe4-9f5c-b5d3e006a640";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn1 = (Button) findViewById(R.id.jai);
    btn2 = (Button) findViewById(R.id.tose);

    mediaPlayer = new MediaPlayer();
    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);

    btn1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
               playjai();
        }
    });
    btn2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
        playtose();

        }
    });

}

public void playjai(){

    if (mediaPlayer.isPlaying()){
        mediaPlayer.stop();
    }
    playmusic(jai);

}

public void playtose(){
    if (mediaPlayer.isPlaying()){
        mediaPlayer.stop();
    }
    playmusic(tose);

}

private void playmusic(String url){

    firebaseStorage = FirebaseStorage.getInstance();
    StorageReference storageRef = firebaseStorage.getReferenceFromUrl(url);
    storageRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
        @Override
        public void onSuccess(Uri uri) {
            try {
                // Download url of file
                 String url = uri.toString();
                mediaPlayer.setDataSource(url);
                // wait for media player to get prepare
                mediaPlayer.setOnPreparedListener( MainActivity.this);
                mediaPlayer.prepareAsync();

            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    })

            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.i("TAG", e.getMessage());
                }
            });


}


@Override
public void onPrepared(MediaPlayer mediaPlayer) {
    try {
        mediaPlayer.start();
    } catch (IllegalStateException e) {
        e.printStackTrace();
    }
}

}

我刚刚添加了两个用于测试应用的按钮。我第一次点击任何按钮，当我点击另一个按钮应用程序时，它将开始播放歌曲。

Answer 1

非常仔细地研究MediaPlayer state diagram及其描述。每次在MediaPlayer上调用方法时，它都必须符合有效的状态转换，否则会抛出IllegalStateException。

您只能在MediaPlayer处于空闲状态时调用setDataSource()。在第一次播放之后，你试图再次调用它。如果要重用同一个MediaPlayer实例，则需要在其上调用reset()将其重新发送回空闲状态，然后再次调用setDataSource()。

具有Firebase多个Mp3文件的Android Media Player

1 个答案: