最近在做项目的时候遇到一个小问题,就是需要自己写一个View来控制系统音乐播放器的播放行为,并且要能得到正在播放的音乐的信息,可能刚开始是想省点时间,所以就没有直接去看源码,而是上网搜索了一下,但令我十分惊讶的是网上竟然没有这个,难道说没有童鞋做过这个?嘿嘿,啥都不说了,开始:
获得系统正在播放的音乐的信息,查看源码可以知道,在Music应用中有一个MediaPlaybackService.java文件,内部的代码我就不写了,总之就是在播放音乐的时候会在四种情况下发送广播,这些广播里面包含了正在播放的音乐的信息,所以我们只要写一个广播来接受这些信息就可以了:
MusicBroadcastReceiver mbr = null;//定义
class MusicBroadcastReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { artistName = intent.getStringExtra("artist"); album = intent.getStringExtra("album"); track = intent.getStringExtra("track"); playing = intent.getBooleanExtra("playing",false); duration = intent.getLongExtra("duration",3000); position = intent.getLongExtra("position",1000); Toast.makeText(TestActivity.this, "playing:" + playing, Toast.LENGTH_SHORT).show(); if(playing){ sd.setVisibility(View.VISIBLE); } else{ if((!sd.isOpened())){ sd.setVisibility(View.GONE); } } if(playing){ ((ImageView)findViewById(R.id.play)).setImageResource(R.drawable.music_pause); }else{ ((ImageView)findViewById(R.id.play)).setImageResource(R.drawable.music_play); } ((TextView)findViewById(R.id.musicName)).setText(track ); ((TextView)findViewById(R.id.musicInfo)).setText(artistName + " / " + album); } }
上面写的是一个广播界接收者,需要在适当的时机进行注册,由于MediaPlaybackService发送的是一个粘性广播,所以我们的这个接收者在应用打开的时候也可以接收到这个广播,不需要管上面我的那些个TextView或者是ImageView。
注册广播:
@Override protected void onResume() { /** * com.android.music.metachanged * com.android.music.queuechanged", * "com.android.music.playbackcomplete" * "com.android.music.playstatechanged" */ mbr = new MusicBroadcastReceiver(); IntentFilter intentFilter = new IntentFilter(); intentFilter.addAction("com.android.music.metachanged"); intentFilter.addAction("com.android.music.queuechanged"); intentFilter.addAction("com.android.music.playbackcomplete"); intentFilter.addAction("com.android.music.playstatechanged"); registerReceiver(mbr, intentFilter); super.onResume(); }
注销广播:
@Override protected void onPause() { if(mbr != null){ unregisterReceiver(mbr); } super.onPause(); }
控制音乐的播放:
同样在Music应用中有一个MediaButtonIntentReceiver接受着,当我们我们可以发送特定的广播来控制音乐的播放,如下:
private static final String SERVICECMD = "com.android.music.musicservicecommand"; private static final String CMDNAME = "command"; /* private static final String CMDTOGGLEPAUSE = "togglepause"; private static final String CMDSTOP = "stop";*/ private static final String CMDPAUSE = "pause"; private static final String CMDPLAY = "play"; private static final String CMDPREVIOUS = "previous"; private static final String CMDNEXT = "next"; public void click(View v){ Intent intent = new Intent(SERVICECMD); switch(v.getId()){ case R.id.pre:{ intent.putExtra(CMDNAME, CMDPREVIOUS); }break; case R.id.play:{ if(playing){ intent.putExtra(CMDNAME,CMDPAUSE); ((ImageView)findViewById(R.id.play)).setImageResource(R.drawable.music_play); }else{ intent.putExtra(CMDNAME,CMDPLAY); ((ImageView)findViewById(R.id.play)).setImageResource(R.drawable.music_pause); } }break; case R.id.next:{ intent.putExtra(CMDNAME,CMDNEXT); }break; } sendBroadcast(intent); }
放送广播的时候也可以不给Inent设置Extra,只需要把:
private static final String SERVICECMD = "com.android.music.musicservicecommand"; private static final String CMDNAME = "command"; /* private static final String CMDTOGGLEPAUSE = "togglepause"; private static final String CMDSTOP = "stop";*/ private static final String CMDPAUSE = "pause"; private static final String CMDPLAY = "play"; private static final String CMDPREVIOUS = "previous"; private static final String CMDNEXT = "next"; 替换为 private static final String pause = "com.android.music.musicservicecommand.pause"; private static final String next = "com.android.music.musicservicecommand.next"; private static final String stop = "com.android.music.musicservicecommand.stop"; private static final String previous = "com.android.music.musicservicecommand.previous";
然后new Intent(pause/next/stop/previous);等通过sendBroadcast(intent);发送也可以,但是我没有亲自验证过,大家可以试一下,第一种是验证过的。
贴出原理图:下面是我做锁屏的时候的图,左边的部分是锁屏相关的,不要受它影响。