Android 中LocalBroadcastManager的使用方式
浏览数：16 /
时间：2015年06月11日
摘要 android中广播的作用非常大，对程序的运行起着非常重要的作用
Android中BroadcastReceiver主要用途有
发送通知，更新UI或者数据，应用程序间相互通信，监听系统状态（比如开机，网络等）
Android中BroadcasetReceiver的注册方式
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manifest清单文件中的全局注册
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按照生命周期，在Service或者Activity中使用代码注册
manifest的注册方式
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<receiver android:name="com.sample.test.MyBroadcastReciever"> <intent-filter> <action android:name="com.sample.test.ACTION_DO_SOMETHING"></action> <action android:name="android.intent.ACTION_WIFI_STATE_CHANGED"></action> </intent-filter> </receiver> |
使用代码注册
SampleActivity
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private MyReceiver receiver;@Override public void onStart() { super.onStart(); receiver = new MyReceiver(); IntentFilter filter = new IntentFilter(); filter.addAction("android.intent.action.MY_BROADCAST"); registerReceiver(receiver, filter);}@Overridepublic void onStop(){ super.onStop(); unregisterReceiver(receiver); } |
Android中发送广播的方式
普通广播：无论优先级大小，将发送给所有监听Action="com.test.sample.action"的广播,内容不可被修改，无传递性。
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Intent intent = new Intent( "com.test.sample.action");sendBroadcast(intent); |
异步（黏性）广播: 当处理完之后的Intent ，依然存在，这时候registerReceiver(BroadcastReceiver, IntentFilter) 还能收到他的值，直到你把它去掉 , 无传递性 , 无法终止(abort())广播。
发这个广播需要权限<uses-permission android:name="android.permission.BROADCAST_STICKY" />
去掉是用这个方法removeStickyBroadcast(intent); 但别忘了在执行这个方法的应用里面 AndroidManifest.xml 同样要加上面的权限；
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sendStickyOrderedBroadcast(intent, resultReceiver, scheduler, initialCode, initialData, initialExtras) |
有序广播：
按照接收者的优先级顺序接收广播 , 优先级别在 intent-filter 中的 priority 中声明 ,-1000 到1000 之间 ，值越大 优先级越高 。可以终止广播意图的继续传播 ， 接收者可以篡改内容，具有传递性。
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sendBroadcast(intent); |
Android中的BroadcastReceiver可以用来发送信息到另一个广播，这种方式可实现程序或者进程间的通行。
上面回顾了一下Android的广播用例，总体来说安全性都不太好，因此只适用于安全性较低的数据传递，或者页面更新。
在android-support-v4.jar中引入了LocalBroadcastManager，称为局部通知管理器，这种通知的好处是安全性高，效率也高，适合局部通信，可以用来代替Handler更新UI
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public class LocalServiceBroadcasterActivity extends Activity { static final String ACTION_STARTED = "com.example.android.supportv4.STARTED"; static final String ACTION_UPDATE = "com.example.android.supportv4.UPDATE"; static final String ACTION_STOPPED = "com.example.android.supportv4.STOPPED"; LocalBroadcastManager mLocalBroadcastManager; BroadcastReceiver mReceiver; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final TextView callbackData = (TextView) findViewById(R.id.callback); callbackData.setText("No broadcast received yet"); mLocalBroadcastManager = LocalBroadcastManager.getInstance(this); IntentFilter filter = new IntentFilter(); filter.addAction(ACTION_STARTED); filter.addAction(ACTION_UPDATE); filter.addAction(ACTION_STOPPED); mReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { if (intent.getAction().equals(ACTION_STARTED)) { callbackData.setText("STARTED"); } else if (intent.getAction().equals(ACTION_UPDATE)) { callbackData.setText("Got update: " + intent.getIntExtra("value", 0)); } else if (intent.getAction().equals(ACTION_STOPPED)) { callbackData.setText("STOPPED"); } } }; mLocalBroadcastManager.registerReceiver(mReceiver, filter); Button button = (Button) findViewById(R.id.start); button.setOnClickListener(mStartListener); button = (Button) findViewById(R.id.stop); button.setOnClickListener(mStopListener); } @Override protected void onDestroy() { super.onDestroy(); mLocalBroadcastManager.unregisterReceiver(mReceiver); } private OnClickListener mStartListener = new OnClickListener() { public void onClick(View v) { startService(new Intent(LocalServiceBroadcasterActivity.this, LocalService.class)); } }; private OnClickListener mStopListener = new OnClickListener() { public void onClick(View v) { stopService(new Intent(LocalServiceBroadcasterActivity.this, LocalService.class)); } }; public static class LocalService extends Service { LocalBroadcastManager mLocalBroadcastManager; int mCurUpdate; static final int MSG_UPDATE = 1; Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_UPDATE: { mCurUpdate++; Intent intent = new Intent(ACTION_UPDATE); intent.putExtra("value", mCurUpdate); mLocalBroadcastManager.sendBroadcast(intent); Message nmsg = mHandler.obtainMessage(MSG_UPDATE); mHandler.sendMessageDelayed(nmsg, 1000); } break; default: super.handleMessage(msg); } } }; @Override public void onCreate() { super.onCreate(); mLocalBroadcastManager = LocalBroadcastManager.getInstance(this); } public int onStartCommand(Intent intent, int flags, int startId) { // Tell any local interested parties about the start. mLocalBroadcastManager.sendBroadcast(new Intent(ACTION_STARTED)); // Prepare to do update reports. mHandler.removeMessages(MSG_UPDATE); Message msg = mHandler.obtainMessage(MSG_UPDATE); mHandler.sendMessageDelayed(msg, 1000); return ServiceCompat.START_STICKY; } @Override public void onDestroy() { super.onDestroy(); // Tell any local interested parties about the stop. mLocalBroadcastManager.sendBroadcast(new Intent(ACTION_STOPPED)); // Stop doing updates. mHandler.removeMessages(MSG_UPDATE); } @Override public IBinder onBind(Intent intent) { return null; } }} |
摘自：http://my.oschina.net/ososchina/blog/340339
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