android 利用 service 實現音樂播放

標籤：android開發   音樂   service   

今天的播放器利用了service，播放音樂在service端，進度條在activity端，因此主要的工作就是activity和service的互動，本文將利用IBinder進行互動，主要是activity可以調用service的函數，可以參考我的這篇部落格。

本文關鍵點：利用利用IBinder實現activity 控制service 

實現功能：

1 控制播放進度：

activity調用service的函數，對MediaPlayer進行控制。包括啟動時的播放和滑動seekbar時，對MediaPlayer進行設定，達到控制播放進度的控制。

2 播放進度更新：

  在activity開啟多線程，後台每隔100ms就發送一次message，在UI線程中利用handler對message進行判定，之後activity調用service的函數，得到播放的進度（百分比），及時更新seekbar的進度條。

如下：

布局很簡單，如下所示：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"     android:orientation="vertical">    <TextView     android:layout_width="wrap_content"    android:layout_height="wrap_content"     android:text="play"/>        <Button     android:id="@+id/playButton"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="play"  /><Button     android:id="@+id/pauseButton"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="pause"  /> <SeekBar        android:id="@+id/seekbar"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="20dp"        android:layout_marginRight="20dp"        android:max="100"        android:progress="10"        /></LinearLayout>

activity的代碼如下：

<pre name="code" class="java">public class MainActivity extends Activity {Boolean mBound = false;MusicService mService;SeekBar seekBar;//多線程，後台更新UIThread myThread;//控制後台線程退出boolean playStatus = true;//處理進度條更新Handler mHandler = new Handler(){@Override          public void handleMessage(Message msg){  switch (msg.what){case 0://從bundle中擷取進度，是double類型，播放的百分比double progress = msg.getData().getDouble("progress");//根據播放百分比，計算seekbar的實際位置             int max = seekBar.getMax();              int position = (int) (max*progress);                        //設定seekbar的實際位置            seekBar.setProgress(position);              break;        default:        break;}                    }  };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//定義一個新線程，用來發送訊息，通知更新UImyThread = new Thread(new MyThread());//綁定service;Intent serviceIntent = new Intent(this , MusicService.class);//如果未綁定，則進行綁定if(!mBound){bindService(serviceIntent, mConnection, Context.BIND_AUTO_CREATE);}//初始化播放按鈕Button playButton = (Button)findViewById(R.id.playButton);playButton.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubif(mBound){mService.play();}}});//初始化暫停按鈕Button pauseButton = (Button)findViewById(R.id.pauseButton);pauseButton.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stub//首先需要判定綁定情況if(mBound){mService.pause();}}});    seekBar = (SeekBar)findViewById(R.id.seekbar);seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {//手動調節進度// TODO Auto-generated method stub//seekbar的拖動位置int dest = seekBar.getProgress();//seekbar的最大值int max = seekBar.getMax();//調用service調節播放進度mService.setProgress(max, dest);}@Overridepublic void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {// TODO Auto-generated method stub}@Overridepublic void onStartTrackingTouch(SeekBar arg0) {// TODO Auto-generated method stub}});}//實現runnable介面，多線程即時更新進度條public class MyThread implements Runnable{//通知UI更新的訊息//用來向UI線程傳遞進度的值Bundle data = new Bundle();//更新UI間隔時間int milliseconds = 100;double progress;@Overridepublic void run() {// TODO Auto-generated method stub//用來標識是否還在播放狀態，用來控制線程退出while(playStatus){                  try {                  //綁定成功才能開始更新UI                    if(mBound){                                        //發送訊息，要求更新UI                                        Message msg = new Message();                    data.clear();                                 progress = mService.getProgress();            msg.what = 0;                        data.putDouble("progress", progress);            msg.setData(data);            mHandler.sendMessage(msg);                    }                    Thread.sleep(milliseconds);          //Thread.currentThread().sleep(milliseconds);  //每隔100ms更新一次UI                        } catch (InterruptedException e) {                      // TODO Auto-generated catch block                      e.printStackTrace();                  }  }}} /** Defines callbacks for service binding, passed to bindService() */      private ServiceConnection mConnection = new ServiceConnection() {            @Override          public void onServiceConnected(ComponentName className,                  IBinder binder) {              // We've bound to LocalService, cast the IBinder and get LocalService instance          MyBinder myBinder = (MyBinder) binder;                    //擷取service        mService = (MusicService) myBinder.getService();                          //綁定成功            mBound = true;                          //開啟線程，更新UI            myThread.start();        }            @Override          public void onServiceDisconnected(ComponentName arg0) {              mBound = false;          }      };     @Overridepublic 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;}@Overridepublic void onDestroy(){//銷毀activity時，要記得銷毀線程playStatus = false;super.onDestroy();}}

service的代碼如下：

public class MusicService extends Service {IBinder musicBinder  = new MyBinder();//擷取到activity的Handler，用來通知更新進度條Handler mHandler; //播放音樂的媒體類MediaPlayer mediaPlayer;//本地歌曲的路徑    String path = "/storage/sdcard1/Music/浪漫滿屋.mp3";        private String TAG = "MyService";@Override      public void onCreate() {          super.onCreate();          Log.d(TAG, "onCreate() executed");                  init();            }    @Overridepublic IBinder onBind(Intent arg0) {// TODO Auto-generated method stub    //當綁定後，返回一個musicBinderreturn musicBinder;}class MyBinder extends Binder{public Service getService(){return MusicService.this;}}//初始化音樂播放void init(){//進入IdlemediaPlayer = new MediaPlayer();try {//初始化mediaPlayer.setDataSource(path);    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);  // prepare 通過非同步方式裝載媒體資源mediaPlayer.prepareAsync();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}//返回當前的播放進度，是double類型，即播放的百分比public double getProgress(){int position = mediaPlayer.getCurrentPosition();                  int time = mediaPlayer.getDuration();                  double progress = (double)position / (double)time;                return progress;  }//通過activity調節播放進度public void setProgress(int max , int dest){int time = mediaPlayer.getDuration();mediaPlayer.seekTo(time*dest/max);}//測試播放音樂public void play(){if(mediaPlayer != null){mediaPlayer.start();}}//暫停音樂       public void pause() {          if (mediaPlayer != null && mediaPlayer.isPlaying()) {              mediaPlayer.pause();          }      }        //service 銷毀時，停止播放音樂，釋放資源  @Override  public void onDestroy() {     // 在activity結束的時候回收資源     if (mediaPlayer != null && mediaPlayer.isPlaying()) {         mediaPlayer.stop();         mediaPlayer.release();         mediaPlayer = null;     }     super.onDestroy();     }}