一篇文章学会使用Broadcast

Broadcast ------传消息和事件的工具

1.注册一个广播

创建一个继承 BroadcastReceiver的类，重写onReceive（）

Kotlin 复制代码

class PlayMusicReceiver(private val callback:(Boolean)->Unit):BroadcastReceiver() {

    override fun onReceive(context: Context?, intent: Intent?) {
     val isPlay = intent!!.getBooleanExtra("EXTRA",true)
     callback(isPlay)
    }
}

在Service中获取刚创建的 BroadcastReceiver和传入了与之前Intent内部action相同的IntentFilter，进行判断可以注册后，调用registerReceiver（）注册Broadcast

Kotlin 复制代码

fun createReceiver(){
      
        val intentFilter = IntentFilter("com.example.zj_action")
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU){
            registerReceiver(mReceiver,intentFilter,Context.RECEIVER_EXPORTED)
        }else{
            registerReceiver(mReceiver,intentFilter)
        }
    }

2.发送广播

自带sendBroacast（），传入一个Intent（action）即可，悄悄说，action是自己取名字当标识符

Intent.putExtra（）可以传递额外值给目标

Kotlin 复制代码

 fun playBroadcast(){
        val intent = Intent("com.example.zj_action")
        intent.putExtra("EXTRA",true)
        sendBroadcast(intent)
    }

3.接收广播

Receiver类中通过高阶函数callback回调了Blooean值,再传递给PlayMusicReceiver的实例化类中

Kotlin 复制代码

 mReceiver = PlayMusicReceiver{
            if (it){
                playMusic("音频的url地址")
            }else{
             player.stop()
            }
        }
      createReceiver()