android版的 MP3 播放器

package hai.test.mp3player; import java.io.File; import java.io.IOException; import android.app.Activity; import android.media.MediaPlayer; import android.os.Bundle; import android.os.Environment; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; public class MP3PlayerActivity extends Activity { private MediaPlayer mediaPlayer; private EditText filenameText; private Button pause; private String filename; private int position; private static final String TAG="MP3PlayerActivity"; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ButtonClick buttonClick=new ButtonClick(); mediaPlayer = new MediaPlayer(); Button play =(Button)findViewById(R.id.play); pause =(Button)findViewById(R.id.pause); Button resume =(Button)findViewById(R.id.resume); Button stop =(Button)findViewById(R.id.stop); filenameText =(EditText)findViewById(R.id.filename); play.setOnClickListener(buttonClick); pause.setOnClickListener(buttonClick); resume.setOnClickListener(buttonClick); stop.setOnClickListener(buttonClick); } @Override protected void onRestoreInstanceState(Bundle savedInstanceState) { position=savedInstanceState.getInt("position"); super.onRestoreInstanceState(savedInstanceState); } @Override protected void onSaveInstanceState(Bundle outState) { if(mediaPlayer.isPlaying()){ outState.putInt("position",mediaPlayer.getCurrentPosition()); } super.onSaveInstanceState(outState); } @Override protected void onPause() { if(mediaPlayer.isPlaying()){ position=mediaPlayer.getCurrentPosition(); mediaPlayer.pause(); } super.onPause(); } @Override protected void onResume() { if(position>0) { mediaPlayer.seekTo(position); mediaPlayer.start(); } super.onResume(); } private class ButtonClick implements View.OnClickListener{ @Override public void onClick(View v) { try { filename=filenameText.getText().toString(); switch (v.getId()) { case R.id.play: paly(); break; case R.id.pause: if(mediaPlayer.isPlaying()){ mediaPlayer.pause(); pause.setText(R.string.contiue); }else { mediaPlayer.start(); pause.setText(R.string.pause); } break; case R.id.resume: if(!mediaPlayer.isPlaying()){ paly(); }else { mediaPlayer.seekTo(0); } break; case R.id.stop: if(mediaPlayer.isPlaying()){ mediaPlayer.stop(); } break; } } catch (Exception e) { Log.e(TAG,e.toString()); } } private void paly() throws IOException { File file=new File(Environment.getExternalStorageDirectory(),filename); mediaPlayer.reset(); mediaPlayer.setDataSource(file.getAbsolutePath()); mediaPlayer.prepare(); mediaPlayer.start(); }} }