BroadcastReceiver广播

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知识背景

广播是一种可以跨进程的通信方式

全局广播

定义广播接收者

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public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
     	//onReceive函数不能做耗时的事情 参考值10s内
    }
    
}

注册

静态注册

在AndroidManifest.xml注册

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<receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">
			<intent-filter>
		<action android:name="com.cczhr.broadcasttest.MY_BROADCAST"/>
		<!--这里指定MyReceiver所要接收的广播名字-->
		</intent-filter>
        </receiver>

动态注册注销

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//注册模块
if(receiver==null){
	receiver=new MyReceiver();
	intentFilter = new IntentFilter();
	intentFilter.addAction("com.cczhr.broadcasttest.MY_BROADCAST");
	//这里指定MyReceiver所要接收的广播名字
	registerReceiver(receiver,intentFilter)
}
//注销模块
if(receiver!=null){
unregisterReceiver(networkChangeReceiver);
}
private IntentFilter intentFilter;
private MyReceiver receiver =null;

发送广播

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Intent intent = new Intent("com.cczhr.broadcasttest.MY_BROADCAST");
sendBroadcast(intent);

有序广播

优先级别越高越先收到广播而且能阻断下一个接收者接收。

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<receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">
			<!--这里指定优先级-->
			<intent-filter android:priority="100">
		<action android:name="com.cczhr.broadcasttest.MY_BROADCAST"/>
		<!--这里指定MyReceiver所要接收的广播名字-->
		</intent-filter>
        </receiver>
<receiver
            android:name=".MyReceiver2"
            android:enabled="true"
            android:exported="true">
			<!--这里指定优先级-->
			<intent-filter android:priority="90">
		<action android:name="com.cczhr.broadcasttest.MY_BROADCAST"/>
		<!--这里指定MyReceiver所要接收的广播名字-->
		</intent-filter>
        </receiver>

MyReceiver

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public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
     	//onReceive函数不能做耗时的事情 参考值10s内
		abortBroadcast();
		//截断广播，这时MyReceiver2接收不了广播
    }
    
}

本地广播

使用这个机制发出的广播只能够在应用程序的内部进行传递，并且广播接收器也只能接收来自本应用程序发出的广播

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private LocalReceiver localReceiver;
//注册本地广播
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.cczhr.broadcasttest.MY_BROADCAST");//可以设置多个
localReceiver = new LocalReceiver();
localBroadcastManager.registerReceiver(localReceiver, intentFilter); 
....
//处理收到的信息
class  LocalReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equals(com.cczhr.broadcasttest.MY_BROADCAST){
			//dosomething
			}
        }
 }
 //最后在注册的onDestroy取消注册
 ...
  LocalBroadcastManager.getInstance(this).unregisterReceiver( localReceiver);
 ....
	
	
//发送本地广播
localBroadcastManager = LocalBroadcastManager.getInstance(this); // 获取实例
Intent intent = new Intent("com.cczhr.broadcasttest.MY_BROADCAST");
localBroadcastManager.sendBroadcast(intent); //传Intent