音乐播放器MusicBox

功能界面分析

界面要求较为简洁，仅需两个TextView，用于输出音乐名称及歌手姓名，下方三个ImageButton，用于播放，暂停或切换上一首，下一首歌曲。

实现

总体规划

在MainActivity中，对三个按钮进行监听，当收到命令时向MusicService发送广播，传送操作要求。

在MusicService中，接受MainActivity传来的广播，对音乐播放，即MediaPlayer进行处理，选择播放，暂停，或者切换歌曲，最后将操作后状态再次通过广播发送到MainActivity。

在MainActivity中，接收MusicService发送的广播，根据当前状态更新界面。

具体代码

MainActivity

public class MainActivity extends Activity implements OnClickListener
{// 获取界面中显示歌曲标题、作者文本框TextView title, author;// 播放/暂停、停止按钮ImageButton play,last,next;ActivityReceiver activityReceiver;public static final String CTL_ACTION ="org.action.CTL_ACTION";public static final String UPDATE_ACTION ="org.action.UPDATE_ACTION";// 定义音乐的播放状态，0x11代表没有播放；0x12代表正在播放；0x13代表暂停int status = 0x11;String[] titleStrs = new String[] { "Young For You", "To The Sky", "闹海","白虎野の娘","那些花儿" };String[] authorStrs = new String[] { "GALA", "Owl City","哪吒", "平沢進","朴树" };@SuppressLint({"WrongViewCast", "CutPasteId"})@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);// 获取程序界面界面中的两个按钮play = findViewById(R.id.play_pause);title =  findViewById(R.id.music_name);author =  findViewById(R.id.singer);last = findViewById(R.id.last);next = findViewById(R.id.next);// 为两个按钮的单击事件添加监听器play.setOnClickListener(this);next.setOnClickListener(this);last.setOnClickListener(this);activityReceiver = new ActivityReceiver();// 创建IntentFilterIntentFilter filter = new IntentFilter();// 指定BroadcastReceiver监听的Actionfilter.addAction(UPDATE_ACTION);// 注册BroadcastReceiverregisterReceiver(activityReceiver, filter);Intent intent = new Intent(this, MusicService.class);// 启动后台ServicestartService(intent);}// 自定义的BroadcastReceiver，负责监听从Service传回来的广播public class ActivityReceiver extends BroadcastReceiver
{@Overridepublic 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);if (current >= 0){title.setText(titleStrs[current]);author.setText(authorStrs[current]);}switch (update){case 0x11:play.setImageResource(R.drawable.ic_play_bar_btn_play);status = 0x11;break;// 控制系统进入播放状态case 0x12:// 播放状态下设置使用暂停图标play.setImageResource(R.drawable.ic_play_bar_btn_pause);// 设置当前状态status = 0x12;break;// 控制系统进入暂停状态case 0x13:// 暂停状态下设置使用播放图标play.setImageResource(R.drawable.ic_play_bar_btn_play);// 设置当前状态status = 0x13;break;}}
}@Overridepublic void onClick(View source){// 创建IntentIntent intent = new Intent("org.action.CTL_ACTION");switch (source.getId()){// 按下播放/暂停按钮case R.id.play_pause:intent.putExtra("control", 1);break;case R.id.next:intent.putExtra("control",2);case R.id.last:intent.putExtra("control",3);}// 发送广播，将被Service组件中的BroadcastReceiver接收到sendBroadcast(intent);}
}

MusicService

public class MusicService extends Service
{MyReceiver serviceReceiver;AssetManager am;String[] musics = new String[] { "GALA - Young For You .mp3", "Owl City - To the Sky .mp3","哪吒 - 闹海.mp3","平沢進  - 白虎野の娘 .mp3","朴树 - 那些花儿.mp3" };MediaPlayer mPlayer;// 当前的状态，0x11代表没有播放；0x12代表正在播放；0x13代表暂停int status = 0x11;// 记录当前正在播放的音乐int current = 0;@Overridepublic IBinder onBind(Intent intent){return null;}@Overridepublic void onCreate(){super.onCreate();am = getAssets();// 创建BroadcastReceiverserviceReceiver = new MyReceiver();// 创建IntentFilterIntentFilter filter = new IntentFilter();filter.addAction(MainActivity.CTL_ACTION);registerReceiver(serviceReceiver, filter);// 创建MediaPlayermPlayer = new MediaPlayer();// 为MediaPlayer播放完成事件绑定监听器mPlayer.setOnCompletionListener(new OnCompletionListener() // ①{@Overridepublic void onCompletion(MediaPlayer mp){current++;if (current >= 4){current = 0;}//发送广播通知Activity更改文本框Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);sendIntent.putExtra("current", current);// 发送广播，将被Activity组件中的BroadcastReceiver接收到sendBroadcast(sendIntent);// 准备并播放音乐prepareAndPlay(musics[current]);}});}public class MyReceiver extends BroadcastReceiver
{@Overridepublic void onReceive(final Context context, Intent intent){int control = intent.getIntExtra("control", -1);switch (control){// 播放或暂停case 1:// 原来处于没有播放状态if (status == 0x11){// 准备并播放音乐prepareAndPlay(musics[current]);status = 0x12;}// 原来处于播放状态else if (status == 0x12){// 暂停mPlayer.pause();// 改变为暂停状态status = 0x13;}// 原来处于暂停状态else if (status == 0x13){// 播放mPlayer.start();// 改变状态status = 0x12;}break;// 停止声音case 2:// 如果原来正在播放或暂停if (status == 0x12 || status == 0x13){// 停止播放mPlayer.stop();prepareAndPlay(musics[(current+1)%5]);status = 0x12;}case 3:// 如果原来正在播放或暂停if (status == 0x12 || status == 0x13){// 停止播放mPlayer.stop();if (current==0) current = 4;else current -=1 ;prepareAndPlay(musics[current]);status = 0x12;}}// 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);// 发送广播，将被Activity组件中的BroadcastReceiver接收到sendBroadcast(sendIntent);}
}private void prepareAndPlay(String music){try{// 打开指定音乐文件AssetFileDescriptor afd = am.openFd(music);mPlayer.reset();// 使用MediaPlayer加载指定的声音文件。mPlayer.setDataSource(afd.getFileDescriptor(),afd.getStartOffset(), afd.getLength());// 准备声音mPlayer.prepare();// 播放mPlayer.start();}catch (IOException e){e.printStackTrace();}}
}

源代码

gitee:https://gitee.com/dwtaiden/MusicBox