Question

这是我的MainActivity.class。我正在尝试为Android制作音乐播放器应用。此播放器将在后台运行。它播放一首歌，但是当我按下后退按钮时，它会在第105和118行显示以下错误。

import com.example.shadowman.audio_player_two.MusicService.MusicBinder;
import android.app.Activity;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.MediaController.MediaPlayerControl;



import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

import static android.content.Context.BIND_AUTO_CREATE;



public class MainActivity extends Activity implements MediaPlayerControl {

    //song list variables
    private ArrayList<Song> songList;
    private ListView songView;

    //service
    private MusicService musicSrv;
    private Intent playIntent;
    //binding
    private boolean musicBound=false;

    //controller
    private MusicController controller;

    //activity and playback pause flags
    private boolean paused=false, playbackPaused=false;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //retrieve list view
        songView = (ListView)findViewById(R.id.song_list);
        //instantiate list
        songList = new ArrayList<Song>();
        //get songs from device
        getSongList();
        //sort alphabetically by title
        Collections.sort(songList, new Comparator<Song>(){
            public int compare(Song a, Song b){
                return a.getTitle().compareTo(b.getTitle());
            }
        });
        //create and set adapter
        SongAdapter songAdt = new SongAdapter(this, songList);
        songView.setAdapter(songAdt);

        //setup controller
        setController();
    }

    //connect to the service
    private ServiceConnection musicConnection = new ServiceConnection(){

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            MusicBinder binder = (MusicBinder)service;
            //get service
            musicSrv = binder.getService();
            //pass list
            musicSrv.setList(songList);
            musicBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            musicBound = false;
        }
    };

    //start and bind the service when the activity starts
    @Override
    protected void onStart() {
        super.onStart();
        if(playIntent==null){
            playIntent = new Intent(this, MusicService.class);
            bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE);
            startService(playIntent);
        }
    }

    //user song select
    public void songPicked(View view){
        musicSrv.setSong(Integer.parseInt(view.getTag().toString()));
        musicSrv.playSong();
        if(playbackPaused){
            setController();
            playbackPaused=false;
        }
        controller.show(0);
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        //menu item selected
        switch (item.getItemId()) {
        case R.id.action_shuffle:
            musicSrv.setShuffle();
            break;
        case R.id.action_end:
            stopService(playIntent);
            musicSrv=null;
            System.exit(0);
            break;
        }
        return super.onOptionsItemSelected(item);
    }

    //method to retrieve song info from device
    public void getSongList(){
        //query external audio
        ContentResolver musicResolver = getContentResolver();
        Uri musicUri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        Cursor musicCursor = musicResolver.query(musicUri, null, null, null, null);
        //iterate over results if valid
        if(musicCursor!=null && musicCursor.moveToFirst()){
            //get columns
            int titleColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media.TITLE);
            int idColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media._ID);
            int artistColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media.ARTIST);
            //add songs to list
            do {
                long thisId = musicCursor.getLong(idColumn);
                String thisTitle = musicCursor.getString(titleColumn);
                String thisArtist = musicCursor.getString(artistColumn);
                songList.add(new Song(thisId, thisTitle, thisArtist));
            } 
            while (musicCursor.moveToNext());
        }
    }

    @Override
    public boolean canPause() {
        return true;
    }

    @Override
    public boolean canSeekBackward() {
        return true;
    }

    @Override
    public boolean canSeekForward() {
        return true;
    }

    @Override
    public int getAudioSessionId() {
        return 0;
    }

    @Override
    public int getBufferPercentage() {
        return 0;
    }

    @Override
    public int getCurrentPosition() {
        if(musicSrv!=null && musicBound && musicSrv.isPng())
            return musicSrv.getPosn();
        else return 0;
    }

    @Override
    public int getDuration() {
        if(musicSrv!=null && musicBound && musicSrv.isPng())
            return musicSrv.getDur();
        else return 0;
    }

    @Override
    public boolean isPlaying() {
        if(musicSrv!=null && musicBound)
            return musicSrv.isPng();
        return false;
    }

    @Override
    public void pause() {
        playbackPaused=true;
        musicSrv.pausePlayer();
    }

    @Override
    public void seekTo(int pos) {
        musicSrv.seek(pos);
    }

    @Override
    public void start() {
        musicSrv.go();
    }

    //set the controller up
    private void setController(){
        controller = new MusicController(this);
        //set previous and next button listeners
        controller.setPrevNextListeners(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                playNext();
            }
        }, new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                playPrev();
            }
        });
        //set and show
        controller.setMediaPlayer(this);
        controller.setAnchorView(findViewById(R.id.song_list));
        controller.setEnabled(true);
    }

    private void playNext(){
        musicSrv.playNext();
        if(playbackPaused){ 
            setController();
            playbackPaused=false;
        }
        controller.show(0);
    }

    private void playPrev(){
        musicSrv.playPrev();
        if(playbackPaused){
            setController();
            playbackPaused=false;
        }
        controller.show(0);
    }

    @Override
    protected void onPause(){
        super.onPause();
        paused=true;
    }

    @Override
    protected void onResume(){
        super.onResume();
        if(paused){
            setController();
            paused=false;
        }
    }

    @Override
    protected void onStop() {
        if(controller !=null) {
            controller.hide();
            controller=null;
        }

        super.onStop();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        stopService(playIntent);
        musicSrv=null;

    }

}

这是错误：

请帮助我理解＆amp;解决这个错误

Answer 1

您需要取消绑定服务：

@Override
protected void onStop() {
    // your onStop code
    if(musicConnection != null) {
        unbindService(musicConnection);
    }
    super.onStop();
}

MainActivity已泄露ServiceConnection

1 个答案: