Android中的广播

Android中的广播分为两种：标准广播和有序广播，标准广播是一种完全异步的广播，在广播发出之后，所有的BroadCastReceiver几乎在同一时间收到这条广播信息，因此他们没有先后顺序之分，这种广播的效率比较高，但是也无法被截断，有序广播是一种同步的广播，在广播发送之后，同一时刻只有一个BroadcastReceiver能收到广播消息，而且是有先后顺序的，优先级高的先执行，并且可以截断正在传递的广播
1、动态注册监听时间变化：定义一个TimeChangeReceiver，这个类继承自BroadcastReceiver的，并且重写父类onReceive()方法，这样当系统时间发声变化时就会得到执行。具体代码如下：

class BroadcastActivity:AppCompatActivity() {

    lateinit var timeChangeReceiver:TimeChangeReceiver
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContentView(R.layout.broadcast_activity)

        val initentFilter=IntentFilter()
        initentFilter.addAction("android.intent.action.TIME_TICK")
        timeChangeReceiver=TimeChangeReceiver()
        registerReceiver(timeChangeReceiver,initentFilter)

    }

    override fun onDestroy() {
        super.onDestroy()
        unregisterReceiver(timeChangeReceiver)
    }

    inner class TimeChangeReceiver:BroadcastReceiver(){
        override fun onReceive(context: Context?, intent: Intent?) {
            Log.d("TAG", "onReceive: changed")
            Toast.makeText(context,"time changed",Toast.LENGTH_LONG).show()
        }

    }

}

打印结果：
06-28 05:06:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed
06-28 05:07:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed
06-28 05:08:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed
06-28 05:09:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed
06-28 05:10:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed
06-28 05:11:00.534 17933-17933/com.app.activitytest D/TAG: onReceive: changed

2、静态注册实现开机启动

class BootComplete :BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
       
        Log.d("TAG", "onReceive: finish")
    }
}

manifest文件

 <receiver android:name=".BootComplete"
            android:exported="true"
            android:enabled="true">
            <intent-filter >
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
            </intent-filter>
        </receiver>