简单音乐播放器

界面如图，采用service服务组建，实现后台播放。包括 播放，暂停，重播，停止功能

下面就让我们一起看看它的实现吧（上图路径中要有音频文件）。

1.界面布局就不介绍了

2.service代码

public class PlayerService extends Service {

     private MediaPlayer player;

     @Override
     public void onCreate() {
            super.onCreate();
           Log. i("" , "onCreate" );
     }

     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
           Log. i("" , "onStartCommand" );
            return super.onStartCommand(intent, flags, startId);
     }

     /**
      * 当activity绑定服务时执行此方法，返回IBinder实现（个人理解，相当于组件间的媒介）
      */
     @Override
     public IBinder onBind(Intent intent) {
           Log. i("" ,"onBind" );
            return new PlayerBinder();
     }

     /**
      * 之所以用implements Player，是因为如果PlayerBinder扩展对外的功能时，不会影响Player的调用，实现解耦
      */
     private class PlayerBinder extends Binder implements Player{

            @Override
            public boolean play(String path) {
                 boolean result = false;
                 try {
                      player = new MediaPlayer();
                      player.setAudioStreamType(AudioManager. STREAM_MUSIC);
                      player.setDataSource(path);
                      player.prepare();
                      player.start();
                     result = true;
                } catch (Exception e) {
                      //IllegalArgumentException, SecurityException, IllegalStateException, IOException(简化处理)
                      return false;
                }
                 return result;
           }

            //播放，暂停切换
            @Override
            public String switchState(String path) {
                String result = "";
                 if( player== null){
                      if(play(path)){
                           result = "暂停";
                     } else {
                           result = "播放";
                     }
                } else if( player.isPlaying()){
                      player.pause();
                     result = "播放";
                } else{
                      player.start();
                     result = "暂停";
                }
                 return result;
           }

            @Override
            public String replay() {
                String result = "";
                 if( player!= null){
                      player.seekTo(0);
                      player.start();
                     result = "暂停";
                }
                 return result;
           }

            @Override
            public String stop() {
                String result = "";
                 if( player!= null){
                      player.stop();
                      player.release();
                      player = null;
                     result = "播放";
                }
                 return result;
           }

            @Override
            public String getPlayerState() {
                String result = "";
                 if( player!= null&& player.isPlaying()){
                     result = "暂停";
                }
                 return result;
           }
     }

     @Override
     public void onDestroy() {
            super.onDestroy();
           Log. i("service" , "onDestory" );
     }
}

Interface文件

public interface Player {

      public boolean play(String path);
      public String switchState(String path);
      public String replay();
      public String stop();
      public String getPlayerState();

}

3.最后贴上activity代码

public class MainActivity extends Activity implements OnClickListener {

      private Player playerInter;
      private EditText etMainPath;
      private PlayerConnection conn = new PlayerConnection();
      private Button btMainPlayPause, btMainReplay, btMainStop;

      @Override
      protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
           setContentView(R.layout. activity_main);
            etMainPath = (EditText) findViewById(R.id.et_main_path );
            btMainPlayPause = (Button) findViewById(R.id.bt_mian_play_pause );
            btMainReplay = (Button) findViewById(R.id.bt_mian_replay );
            btMainStop = (Button) findViewById(R.id.bt_mian_stop );

            btMainPlayPause.setOnClickListener( this);
            btMainReplay.setOnClickListener( this);
            btMainStop.setOnClickListener( this);

            //service只能被创建一次，当activity销毁后，再次创建activity不会重新创建service
           Intent startIntent = new Intent( this, PlayerService.class );
           startService(startIntent);

           Intent bindIntent = new Intent( this, PlayerService.class );
           bindService(bindIntent, conn, BIND_AUTO_CREATE);
     }

      private class PlayerConnection implements ServiceConnection {

            //当连接成功时执行此方法，获得播放器操作接口
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                 playerInter = (Player) service;
                String state = playerInter.getPlayerState();
                 if(!state.equals( "")){
                      btMainPlayPause.setText(state);
                }
           }

            @Override
            public void onServiceDisconnected(ComponentName name) {

           }

     }

      //每次结束时解绑
      @Override
      public void finish() {
            super.finish();
            // 每次结束activity时候，解绑服务连接
           unbindService( conn);
           Log. i("" , "disconnect" );
     }

      @Override
      public void onClick(View v) {
            switch (v.getId()) {
            case R.id. bt_mian_play_pause:
                String playState = playerInter.switchState( etMainPath.getText().toString().trim());
                 if(!playState.equals( "")){
                      btMainPlayPause.setText(playState);
                }
                 break;
            case R.id. bt_mian_replay:
                String replayState = playerInter.replay();
                 if(!replayState.equals( "")){
                      btMainPlayPause.setText(replayState);
                }
                 break;
            case R.id. bt_mian_stop:
                String stopState = playerInter.stop();
                 if(!stopState.equals( "")){
                      btMainPlayPause.setText(stopState);
                }
                 break;
            default:
                 break;
           }
     }

      @Override
      protected void onDestroy() {
            super.onDestroy();
           Log. i("activity" , "onDestory" );
     }

}