Android开发之Broadcast Receive（广播机制）其实开发如此简单

什么是BroadcastReceiver

BroadcastReceiver（广播接收器）用于响应来自其他应用程序或者系统的广播消息。这些消息有时被称为事件或者意图。本质上来讲BroadcastReceiver是一个全局的监听器，隶属于Android四大组件之一。

使用场景

1、不同组件之间通信（包括应用内 / 不同应用之间）
2、Android系统在特定情况下与App之间的消息通信
3、多线程通信

实现

创建DemoBroadcastReceiver

public class DemoBroadcastReceiver extends BroadcastReceiver {private String TAG = "broadcast_get";@Overridepublic void onReceive(Context context, Intent intent) {Log.v(TAG, intent.getStringExtra("value")+isOrderedBroadcast());
//        abortBroadcast();//有序广播时可以根据业务需求进行拦截}
}

注册

注册分为两种形式，动态注册和静态注册

动态注册

动态注册是指在Activity中进行注册，方法如下

        IntentFilter inflater = new IntentFilter();inflater.addAction(SEND_RECEIVER_CODE);inflater.setPriority(666);demoBroadcastReceiver = new DemoBroadcastReceiver();if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {mContext.registerReceiver(demoBroadcastReceiver,inflater, Context.RECEIVER_NOT_EXPORTED);}else {mContext.registerReceiver(demoBroadcastReceiver,inflater);}

静态注册

静态注册指的是在AndroidManifest.xml中进行注册，方法如下

        <receiver android:name=".demo.receiver.DemoBroadcastReceiver"android:enabled="true"android:exported="true"><intent-filter android:priority="500"><action android:name="ACTION_DEMO_SENDER"/></intent-filter></receiver>

发送广播

有序广播

 		Intent intent = new Intent();intent.setAction(SEND_RECEIVER_CODE);intent.setPackage(mContext.getPackageName());intent.putExtra("value","发送广播测试");mContext.sendOrderedBroadcast(intent,null);

无序广播

 		Intent intent = new Intent();intent.setAction(SEND_RECEIVER_CODE);intent.setPackage(mContext.getPackageName());intent.putExtra("value","发送广播测试");mContext.sendBroadcast(intent);

取消注册

 @Overrideprotected void onDestroy() {mContext.unregisterReceiver(demoBroadcastReceiver);super.onDestroy();}

设置优先级

优先级适用于有序广播，值越大，优先级越高（在没有发生优先级倒置的情况下）

 inflater.setPriority(666);

拦截

适用于有序广播，拦截后消息不在发送给其它广播

abortBroadcast();

特别说明

Context.RECEIVER_NOT_EXPORTED 表示为应用内部广播
Context.RECEIVER_EXPORTED 表示可以接收应用外部广播

这部分其实很简单，根据自己的实际情况去使用就可以了

系统广播

常用的系统广播如下

//网络相关的广播
android.net.conn.CONNECTIVITY_CHANGE
android.net.wifi.WIFI_STATE_CHANGED
android.net.wifi.STATE_CHANGE//电池电量的广播
android.intent.action.BATTERY_CHANGED
android.intent.action.BATTERY_LOW//屏幕状态的广播
android.intent.action.SCREEN_ON
android.intent.action.SCREEN_OFF.........

举例

接收系统广播

比如我们想监听一下屏幕是否点亮的需求，就可以如下实现

  		IntentFilter inflater = new IntentFilter();inflater.addAction(SEND_RECEIVER_CODE);inflater.addAction("android.intent.action.SCREEN_OFF");inflater.addAction("android.intent.action.SCREEN_ON");inflater.setPriority(666);demoBroadcastReceiver = new DemoBroadcastReceiver();if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {mContext.registerReceiver(demoBroadcastReceiver,inflater, Context.RECEIVER_EXPORTED);}else {mContext.registerReceiver(demoBroadcastReceiver,inflater);}