<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".MainActivity" >

 <EditText
  android:id="@+id/et_path"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:hint="請(qǐng)輸入音樂文件的路徑" />

 <LinearLayout
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:orientation="horizontal" >

  <Button
   android:id="@+id/bt_play"
   android:layout_width="0dip"
   android:layout_height="wrap_content"
   android:layout_weight="1"
   android:text="播放" />

  <Button
   android:id="@+id/bt_pause"
   android:layout_width="0dip"
   android:layout_height="wrap_content"
   android:layout_weight="1"
   android:text="暫停" />

  <Button
   android:id="@+id/bt_replay"
   android:layout_width="0dip"
   android:layout_height="wrap_content"
   android:layout_weight="1"
   android:text="重播" />

  <Button
   android:id="@+id/bt_stop"
   android:layout_width="0dip"
   android:layout_height="wrap_content"
   android:layout_weight="1"
   android:text="停止" />
 </LinearLayout>

</LinearLayout>

package com.wuyudong.mp3player;

import java.io.File;
import java.io.IOException;

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

 private EditText et_path;
 private Button bt_play, bt_replay, bt_pause, bt_stop;

 private MediaPlayer mediaPlayer;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  et_path = (EditText) findViewById(R.id.et_path);
  bt_play = (Button) findViewById(R.id.bt_play);
  bt_replay = (Button) findViewById(R.id.bt_replay);
  bt_pause = (Button) findViewById(R.id.bt_pause);
  bt_stop = (Button) findViewById(R.id.bt_stop);

  bt_pause.setOnClickListener(this);
  bt_play.setOnClickListener(this);
  bt_replay.setOnClickListener(this);
  bt_stop.setOnClickListener(this);

 }

 @Override
 public void onClick(View v) {
  switch (v.getId()) {
  case R.id.bt_play:
   play();
   break;
  case R.id.bt_replay:
   replay();
   break;
  case R.id.bt_stop:
   stop();
   break;
  case R.id.bt_pause:
   pause();
   break;
  default:
   break;
  }
 }

 /**
  * 暫停音樂
  */
 private void pause() {
  if ("繼續(xù)".equals(bt_pause.getText().toString().trim())) {
   mediaPlayer.start();
   bt_pause.setText("暫停");
   return;
  }
  if (mediaPlayer != null && mediaPlayer.isPlaying()) {
   mediaPlayer.pause();
   bt_pause.setText("繼續(xù)");
   return;
  }
 }

 /**
  * 重新播放
  */
 private void replay() {
  if (mediaPlayer != null && mediaPlayer.isPlaying()) {
   mediaPlayer.seekTo(0);
   return;
  }
  play();
 }

 /**
  * 停止播放音樂
  */
 private void stop() {
  if (mediaPlayer != null && mediaPlayer.isPlaying()) {
   mediaPlayer.stop();
   mediaPlayer.release(); // 記得釋放資源
   mediaPlayer = null;
   bt_play.setEnabled(true);
  }
 }

 /**
  * 播放音樂
  */
 private void play() {
  String path = et_path.getText().toString().trim();
  File file = new File(path);
  if (file.exists() && file.length() > 0) {
   try {
    mediaPlayer = new MediaPlayer();
    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
    mediaPlayer.setDataSource(path);
    mediaPlayer.prepare(); // might take long! (for buffering, etc)
    mediaPlayer.start();
    mediaPlayer.setOnCompletionListener(new OnCompletionListener() {
     @Override
     public void onCompletion(MediaPlayer mp) {
      bt_play.setEnabled(true);
     }
    } );
    
    bt_play.setEnabled(false);
   } catch (Exception e) {
    Toast.makeText(this, "播放失敗", 0).show();
    e.printStackTrace();
   }
  } else {
   Toast.makeText(this, "文件不存在", 0).show();
  }

 }

}