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
}
}

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