练习：多线程实现后台播放背景音乐的service

一、最终结果：

当点击左边按钮时，启动线程，播放音乐。当点击右边按钮时取消线程，音乐停止。

二、工程目录

三、代码

MainActivity.java：

package com.example.service;import android.media.MediaPlayer;import android.os.Bundle;import android.os.IBinder;import android.app.Activity;import android.content.Intent;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.ImageButton;public class MainActivity extends Activity {ImageButton imgbtn1 = null;ImageButton imgbtn2 = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);getViews();// 开始音乐按钮imgbtn1.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {Intent intent = new Intent(MainActivity.this,AudioService.class);startService(intent);}});// 停止音乐按钮imgbtn2.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent = new Intent(MainActivity.this,AudioService.class);stopService(intent);}});}/* * 获取控件 */private void getViews() {imgbtn1 = (ImageButton) findViewById(R.id.imgBtn1);imgbtn2 = (ImageButton) findViewById(R.id.imgBtn2);}/* * 自动播放 */// @Override// protected void onResume() {// super.onResume();// startService(new Intent(this,AudioService.class));// }@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;}}

AudioService.java

package com.example.service;/** * 多线程实现后台播放背景音乐的service */import android.app.Service;import android.content.Intent;import android.media.MediaPlayer;import android.os.Binder;import android.os.IBinder;public class AudioService extends Service implementsMediaPlayer.OnCompletionListener {// 实例化MediaPlayer对象MediaPlayer player;private final IBinder binder = new AudioBinder();@Overridepublic IBinder onBind(Intent intent) {return binder;}public void onCreate() {super.onCreate();// 从raw文件夹中获取一个应用自带的mp3文件player = MediaPlayer.create(this, R.raw.qq);player.setOnCompletionListener(this);player.setLooping(true);}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {super.onStartCommand(intent, flags, startId);if (!player.isPlaying()) {new MusicPlayThread().start();} elseplayer.isPlaying();return START_STICKY;}/** * 当Audio播放完的时候触发该动作 */public void onCompletion(MediaPlayer mp) {stopSelf();// 结束了，则结束Service}public void onDestroy() {super.onDestroy();if (player.isPlaying()) {player.stop();}player.release();}// 为了和Activity交互，我们需要定义一个Binder对象public class AudioBinder extends Binder {// 返回Service对象public AudioService getService() {return AudioService.this;}}private class MusicPlayThread extends Thread {public void run() {if (!player.isPlaying()) {player.start();}}}}

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/LinearLayout2"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <ImageButton        android:id="@+id/imgBtn1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:src="@android:drawable/ic_media_play" />    <ImageButton        android:id="@+id/imgBtn2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:src="@android:drawable/ic_media_pause" /></LinearLayout>

四、遇到问题

1.停止线程方法不会

解决方法：stopService()和stopSelf()都可以停止通过startService()方式启动的service。

                    stopService需要传递startService(Intent service)时的intent对象作为参数，停止此intent对应的service。

                    stopSelf直接停止本service，不需要参数，在service中直接调用即可。

2.音乐存放在文件夹raw中，可以替换成其他mp3文件

五、相关下载

http://download.csdn.net/download/yyd_diablo/8853645