Android 中LocalBroadcastManager的使用方式

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

manifest清单文件中的全局注册
按照生命周期，在Service或者Activity中使用代码注册

manifest的注册方式

<receiverandroid:name="com.sample.test.MyBroadcastReciever"><intent-filter><actionandroid:name="com.sample.test.ACTION_DO_SOMETHING"></action><actionandroid:name="android.intent.ACTION_WIFI_STATE_CHANGED"></action></intent-filter></receiver>

使用代码注册

SampleActivity

privateMyReceiverreceiver;@OverridepublicvoidonStart(){super.onStart();receiver=newMyReceiver();IntentFilterfilter=newIntentFilter();filter.addAction("android.intent.action.MY_BROADCAST");registerReceiver(receiver,filter);}@OverridepublicvoidonStop(){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。

Intentintent=newIntent("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；

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。

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

publicclassLocalServiceBroadcasterActivityextendsActivity{staticfinalStringACTION_STARTED="com.example.android.supportv4.STARTED";staticfinalStringACTION_UPDATE="com.example.android.supportv4.UPDATE";staticfinalStringACTION_STOPPED="com.example.android.supportv4.STOPPED";LocalBroadcastManagermLocalBroadcastManager;BroadcastReceivermReceiver;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);finalTextViewcallbackData=(TextView)findViewById(R.id.callback);callbackData.setText("Nobroadcastreceivedyet");mLocalBroadcastManager=LocalBroadcastManager.getInstance(this);IntentFilterfilter=newIntentFilter();filter.addAction(ACTION_STARTED);filter.addAction(ACTION_UPDATE);filter.addAction(ACTION_STOPPED);mReceiver=newBroadcastReceiver(){@OverridepublicvoidonReceive(Contextcontext,Intentintent){if(intent.getAction().equals(ACTION_STARTED)){callbackData.setText("STARTED");}elseif(intent.getAction().equals(ACTION_UPDATE)){callbackData.setText("Gotupdate:"+intent.getIntExtra("value",0));}elseif(intent.getAction().equals(ACTION_STOPPED)){callbackData.setText("STOPPED");}}};mLocalBroadcastManager.registerReceiver(mReceiver,filter);Buttonbutton=(Button)findViewById(R.id.start);button.setOnClickListener(mStartListener);button=(Button)findViewById(R.id.stop);button.setOnClickListener(mStopListener);}@OverrideprotectedvoidonDestroy(){super.onDestroy();mLocalBroadcastManager.unregisterReceiver(mReceiver);}privateOnClickListenermStartListener=newOnClickListener(){publicvoidonClick(Viewv){startService(newIntent(LocalServiceBroadcasterActivity.this,LocalService.class));}};privateOnClickListenermStopListener=newOnClickListener(){publicvoidonClick(Viewv){stopService(newIntent(LocalServiceBroadcasterActivity.this,LocalService.class));}};publicstaticclassLocalServiceextendsService{LocalBroadcastManagermLocalBroadcastManager;intmCurUpdate;staticfinalintMSG_UPDATE=1;HandlermHandler=newHandler(){@OverridepublicvoidhandleMessage(Messagemsg){switch(msg.what){caseMSG_UPDATE:{mCurUpdate++;Intentintent=newIntent(ACTION_UPDATE);intent.putExtra("value",mCurUpdate);mLocalBroadcastManager.sendBroadcast(intent);Messagenmsg=mHandler.obtainMessage(MSG_UPDATE);mHandler.sendMessageDelayed(nmsg,1000);}break;default:super.handleMessage(msg);}}};@OverridepublicvoidonCreate(){super.onCreate();mLocalBroadcastManager=LocalBroadcastManager.getInstance(this);}publicintonStartCommand(Intentintent,intflags,intstartId){//Tellanylocalinterestedpartiesaboutthestart.mLocalBroadcastManager.sendBroadcast(newIntent(ACTION_STARTED));//Preparetodoupdatereports.mHandler.removeMessages(MSG_UPDATE);Messagemsg=mHandler.obtainMessage(MSG_UPDATE);mHandler.sendMessageDelayed(msg,1000);returnServiceCompat.START_STICKY;}@OverridepublicvoidonDestroy(){super.onDestroy();//Tellanylocalinterestedpartiesaboutthestop.mLocalBroadcastManager.sendBroadcast(newIntent(ACTION_STOPPED));//Stopdoingupdates.mHandler.removeMessages(MSG_UPDATE);}@OverridepublicIBinderonBind(Intentintent){returnnull;}}}

更多相关文章

随机推荐