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我有問題了解綁定到服務 我創建了一個簡單的歌曲播放器，並提供播放歌曲的服務。 我創建了一個日誌來跟蹤綁定和解除綁定。 的問題是，當我退出該應用程序會出現解除綁定日誌，但是當我回去的應用程序是沒有約束力的日誌消息，我能控制歌曲的播放和暫停，雖然Android服務綁定
public class PlayService extends Service {
MediaPlayer mPlayer;
public IBinder mBinder=new LocalBinder();
@Override
public void onCreate() {
super.onCreate();
Log.i("TAG","Create");
mPlayer=MediaPlayer.create(this,R.raw.askme);
}
//since we want the song to be played in the background then we need to start the service
@Override
public int onStartCommand(Intent intent,int flags, int startId) {
Log.i("TAG","Start");
mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mediaPlayer) {
stopSelf();
}
});
return Service.START_NOT_STICKY;
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
Log.i("TAG","Bind");
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("TAG","Unbind");
return super.onUnbind(intent);
}
@Override
public void onRebind(Intent intent) {
Log.i("TAG","ReBind");
super.onRebind(intent);
}
@Override
public void onDestroy() {
Log.i("TAG","Destroy");
mPlayer.release();
super.onDestroy();
}
//here are the play and pause methods frm the user
public void playSong(){
mPlayer.start();
}
public void pauseSong(){
mPlayer.pause();
}
public boolean isPlaying(){
return mPlayer.isPlaying();
}
//since Binder already Extends IBinder so
//we can create LocalBinder Class which extends IBinder Interface
public class LocalBinder extends Binder{
//this method for returning an instance of our service in the MainActivity
public PlayService getService(){
return PlayService.this;
}
}
}
和主要活動如下
public class MainActivity extends AppCompatActivity {
public static final String TAG ="TAG" ;
public PlayService mPlayService;
private Button mDownloadButton;
private Button mSongButton;
private boolean mBound=false;
private ServiceConnection mServiceConnection=new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
//the iBinder object is the returned value from onBind() method in our service
mBound=true;
//we need to get an instance of our service PlayerService so we can play or Pause the song
PlayService.LocalBinder binder = (PlayService.LocalBinder) iBinder;
//and here finally we are getting an instance of our service
mPlayService= binder.getService();
if (mPlayService.isPlaying()){
mSongButton.setText("Pause");
}
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mBound=false;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDownloadButton=(Button) findViewById(R.id.download_button);
mSongButton=(Button) findViewById(R.id.song_button);
mDownloadButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(MainActivity.this,"downloading",Toast.LENGTH_LONG).show();
for (String song:Playlist.songs){
Intent intent=new Intent(MainActivity.this,StartDownloadService.class);
intent.putExtra(TAG,song);
startService(intent);
}
}
});
mSongButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//here we can play or Pause the song
//but first we need to know if we are already bound to the service
if (mBound){
if (mPlayService.isPlaying()){
mPlayService.pauseSong();
mSongButton.setText("Play");
}else {
//but here we need the service to be started and keep playing in the background
//even if we unbound from the service when we exit the App
Intent intent=new Intent(MainActivity.this,PlayService.class);
startService(intent);
mPlayService.playSong();
mSongButton.setText("Pause");
}
}
}
});
}
@Override
protected void onResume() {
Intent intent=new Intent(this,PlayService.class);
bindService(intent,mServiceConnection, Context.BIND_AUTO_CREATE);
super.onResume();
}
@Override
protected void onStop() {
super.onStop();
if (mBound){
unbindService(mServiceConnection);
mBound=false;
}
}
}
，如果有人可以解釋
如果我不啓動服務，歌曲將停止，如果我退出應用程序 –
而不是您在其他部分中的startService意圖，則還會在其他部分調用綁定服務代碼。 –