在另一个活动中播放媒体文件

Question

I have retrieved the songs present on my phone and when I click on the list item it switches to the next activity and plays the song.

But when I go back to my playlist and click again on another song, the previous song is still being played as well as the song I just clicked.

Here is the code of Playlist.java :

package com.example.padyplayer;

import java.io.IOException;
import java.util.ArrayList;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;

 public class Playlist extends Activity implements OnItemClickListener {

ListView tracks_view;
ArrayList<String> songs;
ArrayAdapter<String> songs_items;
//MediaPlayer mediaplayer;
//AudioManager audiomanager;
Cursor cursor;
Uri uri;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_playlist);
    tracks_view = (ListView) findViewById(R.id.tracks);
    generate_Playlist();
    songs_items = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, songs);
    //mediaplayer = new MediaPlayer();
    //audiomanager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    tracks_view.setAdapter(songs_items);
    tracks_view.setOnItemClickListener(this); 

}

@SuppressWarnings("deprecation")
private void generate_Playlist() {
    // TODO Auto-generated method stub
    uri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    String projection[] = { android.provider.MediaStore.Audio.Media.DATA,
            android.provider.MediaStore.Audio.Media.TITLE,
            android.provider.MediaStore.Audio.Media.ARTIST,
            android.provider.MediaStore.Audio.Media.ALBUM,
            android.provider.MediaStore.Audio.Media.DURATION };
    cursor=this.managedQuery(uri, projection, null, null, null);
    songs=new ArrayList<String>();
    while(cursor.moveToNext())
    {
        songs.add(cursor.getString(1));
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.playlist, menu);
    return true;
}

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position, long id) {
    // TODO Auto-generated method stub
    //cursor.moveToPosition(position);
    int index1=position;
    Intent i=new Intent(getApplicationContext(),Controls.class);
    i.putExtra("index", index1);
    startActivity(i);

}

}

Here is the second class Controls.java :

package com.example.padyplayer;

import java.io.IOException;
import java.util.ArrayList;

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class Controls extends Activity implements OnClickListener {

TextView song_view,artist_view;
Button play,next,back;
MediaPlayer mediaplayer=new MediaPlayer();
AudioManager audiomanager;
ArrayList<String> songs;
Cursor cursor;
Uri uri;
private int index=0;
//ArrayAdapter<String> song_items;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_controls);
    play=(Button)findViewById(R.id.play);
    next=(Button)findViewById(R.id.next);
    back=(Button)findViewById(R.id.back);
    play.setOnClickListener(this);
    next.setOnClickListener(this);
    back.setOnClickListener(this);
    //mediaplayer=new MediaPlayer();
    audiomanager=(AudioManager)getSystemService(Context.AUDIO_SERVICE);
    getMusic();
    Bundle b=getIntent().getExtras();
    index = b.getInt("index");
    playSong(index);
}




@SuppressWarnings("deprecation")
private void getMusic() {
    // TODO Auto-generated method stub
    uri=android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    String projection[]={android.provider.MediaStore.Audio.Media.DATA,
            android.provider.MediaStore.Audio.Media.TITLE,
            android.provider.MediaStore.Audio.Media.ARTIST,
            android.provider.MediaStore.Audio.Media.ALBUM,
            android.provider.MediaStore.Audio.Media.DURATION};
    cursor=this.managedQuery(uri, projection, null, null,null);
    songs=new ArrayList<String>();
    while (cursor.moveToNext()) {
        songs.add(cursor.getString(1));
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.controls, menu);
    return true;
}

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()) {
    case R.id.play:
        if(mediaplayer.isPlaying())
        {
            mediaplayer.pause();
            play.setText("play");
        }
        else if(mediaplayer!=null)
        {
            mediaplayer.start();
            play.setText("pause");

        }
        break;
    case R.id.next:
        if(index<(songs.size()-1)){
            index+=1;
            playSong(index);
        }
        else
        {
            index=0;
            playSong(index);
        }
        break;
    case R.id.back:
        if(index>0){
            index-=1;
            playSong(index);
        }
        else
        {
            index=songs.size()-1;
            playSong(index);
        }
        break;


    default:
        break;
    }
    //

}

private void playSong(int index2) {
    // TODO Auto-generated method stub
    cursor.moveToPosition(index2);
    int song_id=cursor.getColumnIndex(MediaStore.Audio.Media.DATA);
    String song_name=cursor.getString(song_id);

    try {
        mediaplayer.reset();
        mediaplayer.setDataSource(song_name);
        mediaplayer.prepare();
        mediaplayer.start();
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

I'm stuck with this problem since two days. Please help.

Answer 1

My advice: use a Service to host the MediaPlayer and have your Activities communicate with the Service to play and stop songs. Don't forget to call release on the MediaPlayer when you are done (if you use a new player for the next song).

Edit:

The Activity is not going to be the same instance each time it opens, and you create a new MediaPlayer each time an instance of the Activity is created. Underneath the hood, there is a native object actually playing the music that is not intrinsically tied to the life cycle of the Activity, and you aren't calling stop or pause anywhere that would get called when Activities are changed. You could potentially stop and release the MediaPlayer in an appropriate callback (onPause or onDestroy), but that will prevent you from playing music continuously. If you insist on using an Activity to host the MediaPlayer, then music playback has to be completely integrated into the life cycle of the Activity. When the Activity is changed, you need to stop and release its resources explicitly. If you put it in a Service, you won't have that limitation. You can manage one or more MediaPlayers ( note the setNextMediaPlayer method ) without them being tied to any particular Activity.

Answer 2

it will keep playing. You need to free your media player object when you press back button. In onPause(), release your media player object otherwise it will keep playing.

To implement music player, you can refer open source code. Refer VLC player source code.

Answer 3

每次从mMediaPlayer.reset()开始播放歌曲之前，您都可以每次播放新歌曲，或者检查是否正在播放mediaplayer，如果停止播放