Android使用Service及BroadcastReceiver实现音乐播放器移动开发weixin41553587的博客-

播放音乐，我们需要在AndroidManifest.xml文件添加权限

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

创建Service，需要在AndroidManifest.xml文件配置

 <service             android:name=".MusicService"             android:enabled="true"             android:exported="true"></service>

现在我们创建了一个叫做MusicService的Service，它是继承Service类的

话不多说，先看看效果图

布局文件：

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical"     android:paddingBottom="@dimen/activity_vertical_margin"     android:paddingLeft="@dimen/activity_horizontal_margin"     android:paddingRight="@dimen/activity_horizontal_margin"     android:paddingTop="@dimen/activity_vertical_margin">      <TextView         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:id="@+id/songName"         android:text="打击乐器"         android:textSize="15sp"         android:layout_marginTop="5dp"/>     <ImageView         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:src="@mipmap/img"         android:id="@+id/Image"         android:layout_gravity="center" />      <!--显示歌曲状态-->     <TextView         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text=""         android:id="@+id/MusicStatus"/>      <RelativeLayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_gravity="center"         android:layout_margin="5dp"         android:gravity="center_horizontal">          <!--显示当前进度-->         <TextView             android:id="@+id/MusicTime"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="00:00" />          <SeekBar             android:layout_width="230sp"             android:layout_height="wrap_content"             android:id="@+id/MusicSeekBar"             android:layout_weight="1"             android:max="100"             android:layout_toRightOf="@+id/MusicTime"/>          <!--显示总进度-->         <TextView             android:id="@+id/MusicTotal"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="00:16"             android:layout_toRightOf="@+id/MusicSeekBar"/>      </RelativeLayout>      <LinearLayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_marginTop="15dp"         android:gravity="center_horizontal"         android:orientation="horizontal">          <Button             android:id="@+id/BtnPrev"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_marginRight="15dp"             android:background="@drawable/shape"             android:text="PREV"             android:textAllCaps="false"             android:textColor="@color/colorWhite" />          <Button             android:id="@+id/BtnPlayorStop"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:background="@drawable/shape"             android:layout_marginRight="15dp"             android:text="PLAY"             android:textAllCaps="false"             android:textColor="@color/colorWhite" />          <Button             android:id="@+id/BtnNext"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:background="@drawable/shape"             android:text="NEXT"             android:textAllCaps="false"             android:textColor="@color/colorWhite" />     </LinearLayout>  </LinearLayout>  

Activity部分代码：

 package com.example.ch8;  import androidx.appcompat.app.AppCompatActivity;  import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.media.MediaPlayer; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.text.Editable; import android.text.TextWatcher; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.SeekBar; import android.widget.TextView;  import java.text.SimpleDateFormat; import java.util.Date; import java.util.Locale;  public class MainActivity extends AppCompatActivity implements View.OnClickListener{     //定义音乐播放状态，0x10代表上一首,0x11代表没有播放或暂停，0x12代表正在播放，0x13代表下一首，0x15表示暂停     int status = 0x11;     static long mediaPlayerDuration = 1L;     static int sum=0;     //三个按钮     Button prve,playorpause,next;     static SeekBar seekBar;     //歌曲名     static TextView songname,starttime,endtime;     ActivityReceiver mActivityReceiver;      String[] name=new String[]{"打击乐器","康加舞","蓝调小号","手拍鼓"};     public static final String CTL_ACTION = "com.trampcr.action.CTL_ACTION";     public static final String UPDATE_ACTION = "com.trampcr.action.UPDATE_ACTION";      //运用Handler中的handleMessage方法接收service传递的音乐播放进度信息     public static Handler handler = new Handler(new Handler.Callback() {         @Override         public boolean handleMessage(Message msg) {             // super.handleMessage(msg);             // 将SeekBar位置设置到当前播放位置，             // msg.arg1是service传过来的音乐播放进度信息,将其设置为进度条进度             seekBar.setProgress(msg.arg1/((int)(mediaPlayerDuration*10)));             //将进度时间其转为mm:ss时间格式             starttime.setText(new SimpleDateFormat("mm:ss", Locale.getDefault()).format(new Date(msg.arg1)));             return false;         }     });     @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          songname=findViewById(R.id.songName);         starttime=findViewById(R.id.MusicTime);         endtime=findViewById(R.id.MusicTotal);         prve=findViewById(R.id.BtnPrev);         playorpause=findViewById(R.id.BtnPlayorStop);         next=findViewById(R.id.BtnNext);         seekBar=findViewById(R.id.MusicSeekBar);          prve.setOnClickListener(this);         playorpause.setOnClickListener(this);         next.setOnClickListener(this);          mActivityReceiver = new ActivityReceiver();         //创建IntentFilter         IntentFilter filter = new IntentFilter();         //指定BroadcastReceiver监听的Action         filter.addAction(UPDATE_ACTION);         //注册BroadcastReceiver         registerReceiver(mActivityReceiver, filter);          Intent intent = new Intent(MainActivity.this, MusicService.class);         //启动后台Service         startService(intent);         Log.i("1","启动服务");      }      //接收service的消息     public class ActivityReceiver extends BroadcastReceiver {          @Override         public void onReceive(Context context, Intent intent) {             //获取Intent中的update消息，update代表播放状态             int update = intent.getIntExtra("update", -1);             //获取Intent中的current消息，current代表当前正在播放的歌曲             int current = intent.getIntExtra("current", -1);             int pro=intent.getIntExtra("process",-1);             mediaPlayerDuration=intent.getLongExtra("endtime",-1);             seekBar.setProgress(pro);             String time=null;             if(mediaPlayerDuration<10){                 time="0"+mediaPlayerDuration;             }             else {                 time=""+mediaPlayerDuration;             }             songname.setText(name[current]);             switch (update){                 case 0x11:                     playorpause.setText("PLAY");                     endtime.setText("00:"+time);                     status = 0x11;                     break;                 //控制系统进入播放状态                 case 0x12:                     //在播放状态下设置使用暂停图标                     playorpause.setText("PAUSE");                     endtime.setText("00:"+time);                     status = 0x12;                     break;                 case 0x15:                     playorpause.setText("PLAY");                     endtime.setText("00:"+time);                     status = 0x15;                     break;             }         }     }      @Override     public void onClick(View v) {         Intent intent = new Intent(CTL_ACTION);         Log.i("1","发送消息");         switch (v.getId()){             case R.id.BtnPrev:                 intent.putExtra("control", 1);                 break;             case R.id.BtnPlayorStop:                 if(status==0x11||status==0x15){                     intent.putExtra("control", 2);                 }                 else if(status==0x12){                     intent.putExtra("control", 3);                 }                 break;             case R.id.BtnNext:                 intent.putExtra("control", 4);                 break;         }          //发送广播，将被Service中的BroadcastReceiver接收到         sendBroadcast(intent);     }   } 

 MusicService部分代码：

 package com.example.ch8;  import android.app.Service; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.content.res.AssetFileDescriptor; import android.content.res.AssetManager; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.Handler; import android.os.IBinder; import android.os.Message; import android.util.Log;  import java.util.Timer; import java.util.TimerTask;  public class MusicService extends Service{     long mediaPlayerDuration = 0L;     MyReceiver serviceReceiver;     AssetManager am;      int[] musics1=new int[]{R.raw.music1,R.raw.music2,R.raw.music3,R.raw.music4};     static MediaPlayer mPlayer;     //定义音乐播放状态，0x10代表上一首,0x11代表没有播放，0x12代表正在播放，0x13代表下一首，0x15表示暂停     int status = 0x11;     //记录当前正在播放的音乐     static int current = 0;      @Override     public IBinder onBind(Intent intent) {         // TODO Auto-generated method stub         return null;     }      @Override     public void onCreate() {         super.onCreate();         Log.i("1","服务创建");         am = getAssets();         //创建BroadcastReceiver         serviceReceiver =new MyReceiver();         //创建IntentFilter         IntentFilter filter = new IntentFilter();         filter.addAction(MainActivity.CTL_ACTION);         registerReceiver(serviceReceiver, filter);         //创建MediaPlayer         mPlayer = new MediaPlayer();      }      private void prepareAndPlay(int mus) {         // TODO Auto-generated method stub         try {             mPlayer=MediaPlayer.create(this,mus);             //为MediaPlayer播放完成事件绑定监听器             mPlayer.setOnCompletionListener(new OnCompletionListener() {                 @Override                 public void onCompletion(MediaPlayer mp) {                     //Log.d("tag", "播放完毕");                     current++;                     status=0x12;                     if(current >=4){                         current = 0;                     }                     //准备并播放音乐                     prepareAndPlay(musics1[current]);                     mediaPlayerDuration=mPlayer.getDuration()/1000;                     //发送广播通知Activity更改文本框                     Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);                     sendIntent.putExtra("update", status);                     sendIntent.putExtra("current", current);                     sendIntent.putExtra("endtime",mediaPlayerDuration);                     //发送广播，将被Activity组件中的BroadcastReceiver接收到                     sendBroadcast(sendIntent);                 }             });             //播放             mPlayer.start();             //每隔500毫秒发送音乐进度             Timer timer = new Timer();             timer.schedule(new TimerTask() {                 @Override                 public void run() {                     //实例化一个Message对象                     Message msg = Message.obtain();                     //Message对象的arg1参数携带音乐当前播放进度信息，类型是int                     msg.arg1 = mPlayer.getCurrentPosition();                     //使用MainActivity中的handler发送信息                     MainActivity.handler.sendMessage(msg);                 }             }, 0, 500);         } catch (Exception e) {             // TODO: handle exception         }     }      public class MyReceiver extends BroadcastReceiver{          @Override         public void onReceive(Context context, Intent intent) {             int control = intent.getIntExtra("control", -1);             switch (control) {                 case 1:                     //上一首                     if(mPlayer.isPlaying()){                         mPlayer.stop();                     }                     int t=mPlayer.getCurrentPosition();                     Log.i("11",""+t);                     if(t>2000)                         current--;                     if(current <0){                         current = 3;                     }                     prepareAndPlay(musics1[current]);                     mediaPlayerDuration=mPlayer.getDuration()/1000;                     status = 0x12;                      break;                 case 2:                     //原来处于没有播放状态                     if(status == 0x11||!mPlayer.isPlaying()){                         prepareAndPlay(musics1[current]);                         mediaPlayerDuration=mPlayer.getDuration()/1000;                         status = 0x12;                     }                     else if(status==0x15){                         mPlayer.start();                         status = 0x12;                     }                      break;                 case 3:                     //正在播放                     if(status ==  0x12){                         //暂停播放                         mPlayer.pause();                         mediaPlayerDuration=mPlayer.getDuration()/1000;                         status=0x15;                     }                     break;                 case 4:                     //下一首                     if(mPlayer.isPlaying()){                         mPlayer.stop();                     }                     current++;                     Log.i("1",current+"");                     if(current >=4){                         current = 0;                      }                     prepareAndPlay(musics1[current]);                     mediaPlayerDuration=mPlayer.getDuration()/1000;                     status = 0x12;                     break;             }             //广播通知Activity更改图标，文本框             Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);             sendIntent.putExtra("update", status);             sendIntent.putExtra("current", current);             sendIntent.putExtra("endtime",mediaPlayerDuration);             //发送广播，将被Activity组件中的BroadcastReceiver接收到             sendBroadcast(sendIntent);         }      }     //获取播放进度     private long getCurrentPosition(){         if(mPlayer.isPlaying()){             return mPlayer.getCurrentPosition();         }         return 0;     }   } 

activity和MusicService部分，它们有内部类ActivityReceiver，MyReceiver继承自BroadcastReceiver，接收和发送来自各自的消息，用来互相通信

MusicService部分有一个定时器，用来定时计算音乐播放进度，并发送消息给activity

activity里有一个Handler来接收MusicService的定时器发送过来的消息，并在前台设置进度显示

 mPlayer.getCurrentPosition();是获取播放实时进度的方法

 mPlayer.getDuration()是获取音乐文件总时长

他们返回的都是一个整型整数