android之音乐播放器

 

public class PlayActivity extends Activity {
 private static final String TAG = "PlayActivity";
    private EditText filenameText;
    private MediaPlayer mediaPlayer;
    private String filename;
    private int position;
   
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        filenameText = (EditText)this.findViewById(R.id.filename);
      
        mediaPlayer = new MediaPlayer();
        ButtonClickListener listener = new ButtonClickListener();
        Button playButton = (Button)this.findViewById(R.id.play);
        Button pauseButton = (Button)this.findViewById(R.id.pause);
        Button resetButton = (Button)this.findViewById(R.id.reset);
        Button stopButton = (Button) this.findViewById(R.id.stop);
        playButton.setOnClickListener(listener);
        pauseButton.setOnClickListener(listener);
        resetButton.setOnClickListener(listener);
        stopButton.setOnClickListener(listener);
        Log.i(TAG, "onCreate()");
    }
   
    @Override
 protected void onRestoreInstanceState(Bundle savedInstanceState) {
  this.filename = savedInstanceState.getString("filename");
  this.position = savedInstanceState.getInt("position");
  super.onRestoreInstanceState(savedInstanceState);
  Log.i(TAG, "onRestoreInstanceState()");
 }

 @Override
 protected void onSaveInstanceState(Bundle outState) {
  outState.putString("filename", filename);
  outState.putInt("position", position);
  super.onSaveInstanceState(outState);
  Log.i(TAG, "onSaveInstanceState()");
 }

 @Override
 protected void onPause() {//如果突然电话到来，停止播放音乐
  if(mediaPlayer.isPlaying()){
   position = mediaPlayer.getCurrentPosition();//保存当前播放点
   mediaPlayer.stop();
  }
  super.onPause();
 }

 @Override
 protected void onResume() {
  if(position>0 && filename!=null){//如果电话结束，继续播放音乐
   try {
    play();
    mediaPlayer.seekTo(position);
    position = 0;
   } catch (IOException e) {
    Log.e(TAG, e.toString());
   }
  }
  super.onResume();
 }

 @Override
 protected void onDestroy() {
     mediaPlayer.release();    
  super.onDestroy();
  Log.i(TAG, "onDestroy()");
 }

 private final class ButtonClickListener implements View.OnClickListener{
  @Override
  public void onClick(View v) {
   filename = filenameText.getText().toString();//先得到文本框中的内容
   Button button = (Button) v;//得到button
   try {
    switch (v.getId()) {//通过传过来的Buttonid可以判断Button的类型
    case R.id.play://播放
     play();
     break;

    case R.id.pause:
     if(mediaPlayer.isPlaying()){
      mediaPlayer.pause();
      button.setText(R.string.continue1);//让这个按钮上的文字显示为继续
     }else{
      mediaPlayer.start();//继续播放
      button.setText(R.string.pause);
     }
     break;
     
    case R.id.reset:
     if(mediaPlayer.isPlaying()){
      mediaPlayer.seekTo(0);//让它从0开始播放
     }else{
      play();//如果它没有播放，就让它开始播放
     }
     break;
     
    case R.id.stop:
     if(mediaPlayer.isPlaying()) mediaPlayer.stop();//如果它正在播放的话，就让他停止
     break;
    }
   } catch (Exception e) {//抛出异常
    Log.e(TAG, e.toString());
   }
  }  
    }
 private void play() throws IOException {
  File audioFile = new File(Environment.getExternalStorageDirectory(),filename);
  mediaPlayer.reset();
  mediaPlayer.setDataSource(audioFile.getAbsolutePath());
  mediaPlayer.prepare();
  mediaPlayer.start();//播放
 }
}