Android多媒体--利用Service实现背景音乐的播放

From:http://blog.csdn.net/chenjie19891104/article/details/6330720

 

Android允许我们使用Service组件来完成后台任务，这些任务的允许不会影响到用户其他的交互。

 

1、Activity类

package demo.camera;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
/**
 * 演示Activity如何利用Service来完成后台Audio的播放功能
 * 同时如何将Service和Activity进行绑定
 * @author Administrator
 *
 */
public class BackgroundAudioDemo extends Activity {

    private AudioService audioService;

    //使用ServiceConnection来监听Service状态的变化
    private ServiceConnection conn = new ServiceConnection() {

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub
            audioService = null;
        }

        @Override
        public void onServiceConnected(ComponentName name, IBinder binder) {
            //这里我们实例化audioService,通过binder来实现
            audioService = ((AudioService.AudioBinder)binder).getService();

        }
    };

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.back_audio);
    }


    public void onClick(View v){
        int id = v.getId();
        Intent intent = new Intent();
        intent.setClass(this, AudioService.class);
        if(id == R.id.btn_start){
            //启动Service，然后绑定该Service，这样我们可以在同时销毁该Activity，看看歌曲是否还在播放
            startService(intent);
            bindService(intent, conn, Context.BIND_AUTO_CREATE);
            finish();
        }else if(id == R.id.btn_end){
            //结束Service
            unbindService(conn);
            stopService(intent);
            finish();
        }else if(id == R.id.btn_fun){
            audioService.haveFun();
        }
    }
}

package demo.camera; import android.app.Activity; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.IBinder; import android.view.View; /** * 演示Activity如何利用Service来完成后台Audio的播放功能 * 同时如何将Service和Activity进行绑定 * @author Administrator * */ public class BackgroundAudioDemo extends Activity { private AudioService audioService; //使用ServiceConnection来监听Service状态的变化 private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { // TODO Auto-generated method stub audioService = null; } @Override public void onServiceConnected(ComponentName name, IBinder binder) { //这里我们实例化audioService,通过binder来实现 audioService = ((AudioService.AudioBinder)binder).getService(); } }; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.back_audio); } public void onClick(View v){ int id = v.getId(); Intent intent = new Intent(); intent.setClass(this, AudioService.class); if(id == R.id.btn_start){ //启动Service，然后绑定该Service，这样我们可以在同时销毁该Activity，看看歌曲是否还在播放 startService(intent); bindService(intent, conn, Context.BIND_AUTO_CREATE); finish(); }else if(id == R.id.btn_end){ //结束Service unbindService(conn); stopService(intent); finish(); }else if(id == R.id.btn_fun){ audioService.haveFun(); } } }

2、Service类

package demo.camera;
import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.IBinder;
import android.widget.MediaController.MediaPlayerControl;
/**
 * 为了可以使得在后台播放音乐，我们需要Service
 * Service就是用来在后台完成一些不需要和用户交互的动作
 * @author Administrator
 *
 */
public class AudioService extends Service implements MediaPlayer.OnCompletionListener{

    MediaPlayer player;

    private final IBinder binder = new AudioBinder();
    @Override
    public IBinder onBind(Intent arg0) {
        // TODO Auto-generated method stub
        return binder;
    }
    /**
     * 当Audio播放完的时候触发该动作
     */
    @Override
    public void onCompletion(MediaPlayer player) {
        // TODO Auto-generated method stub
        stopSelf();//结束了，则结束Service
    }

    //在这里我们需要实例化MediaPlayer对象
    public void onCreate(){
        super.onCreate();
        //我们从raw文件夹中获取一个应用自带的mp3文件
        player = MediaPlayer.create(this, R.raw.tt);
        player.setOnCompletionListener(this);
    }

    /**
     * 该方法在SDK2.0才开始有的，替代原来的onStart方法
     */
    public int onStartCommand(Intent intent, int flags, int startId){
        if(!player.isPlaying()){
            player.start();
        }
        return START_STICKY;
    }

    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
    class AudioBinder extends Binder{

        //返回Service对象
        AudioService getService(){
            return AudioService.this;
        }
    }

    //后退播放进度
    public void haveFun(){
        if(player.isPlaying() && player.getCurrentPosition()>2500){
            player.seekTo(player.getCurrentPosition()-2500);
        }
    }
}

package demo.camera; import android.app.Service; import android.content.Intent; import android.media.MediaPlayer; import android.os.Binder; import android.os.IBinder; import android.widget.MediaController.MediaPlayerControl; /** * 为了可以使得在后台播放音乐，我们需要Service * Service就是用来在后台完成一些不需要和用户交互的动作 * @author Administrator * */ public class AudioService extends Service implements MediaPlayer.OnCompletionListener{ MediaPlayer player; private final IBinder binder = new AudioBinder(); @Override public IBinder onBind(Intent arg0) { // TODO Auto-generated method stub return binder; } /** * 当Audio播放完的时候触发该动作 */ @Override public void onCompletion(MediaPlayer player) { // TODO Auto-generated method stub stopSelf();//结束了，则结束Service } //在这里我们需要实例化MediaPlayer对象 public void onCreate(){ super.onCreate(); //我们从raw文件夹中获取一个应用自带的mp3文件 player = MediaPlayer.create(this, R.raw.tt); player.setOnCompletionListener(this); } /** * 该方法在SDK2.0才开始有的，替代原来的onStart方法 */ public int onStartCommand(Intent intent, int flags, int startId){ if(!player.isPlaying()){ player.start(); } return START_STICKY; } 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 class AudioBinder extends Binder{ //返回Service对象 AudioService getService(){ return AudioService.this; } } //后退播放进度 public void haveFun(){ if(player.isPlaying() && player.getCurrentPosition()>2500){ player.seekTo(player.getCurrentPosition()-2500); } } }

3、在清单文件AndroidManifest.xml中配置Service

 

        <service
            android:name=".AudioService" />