android开发 跨进程通讯之 Messenger

跨进程通讯方式之一 Messenger

准备工作

准备一个 App 同时打开多个进程 这里使用 Service 作为另一个进程

 <service android:name=".MyService"
            android:process=":dbService"/>

class MyService: Service() {
//获取主进程发送过来的消息体
private var message: Message? = null
/**
* 创建Messenger 作为 IBinder
*/
 private lateinit var mMessenger: Messenger
 /**
 *接收消息的Handler
 */
 private val mHandler: Handler by lazy {
        object : Handler(Looper.getMainLooper()) {
            override fun handleMessage(msg: Message) {
                if (msg.data != null) {
                    //获取主进程传递过来的数据
                }
                message = Message.obtain(msg)
                sendMessage(0,1)
                super.handleMessage(msg)
            }
        }
    }

 override fun onCreate() {
        super.onCreate()
    }

    override fun onBind(intent: Intent?): IBinder? {
    //调用 bindService 时会调用该方法 返回 IBinder，主进程中通过返回的 IBinder 向子进程发送消息
        mMessenger = Messenger(mHandler)
        return mMessenger.binder
    }
//发送消息
  fun sendMessage(type: Int, count: Int) {
        message?.what = type
        message?.arg1 = count
        //获取主进程发送过来的消息体中携带的 replyTo 并向他发送消息
        message?.replyTo?.send(message)
    }
}

主进程准备

class OtherProvider{
  	//主进程中用于接收消息的handler
    val hander = object :Handler(Looper.getMainLooper()){
        override fun handleMessage(msg: Message) {
            //接收到子进程发送过来的消息
            super.handleMessage(msg)
        }

    }

    var messenger: Messenger? = null
    //绑定回调，在此绑定消息 handler
    private val mServiceConnection: ServiceConnection = object : ServiceConnection {
        override fun onServiceConnected(name: ComponentName, service: IBinder) {
            messenger = Messenger(service)
            try {
                val message = Message.obtain(hander, 0, 10, 0)
                message.data = Bundle().apply {
                    putString("TITLE","title")
                }
                //关键 将主进程hander 一起发送给子进程 
                message.replyTo = Messenger(hander)
                messenger!!.send(message)
            } catch (e: RemoteException) {
                throw RuntimeException(e)
            }
        }

        override fun onServiceDisconnected(name: ComponentName) {}
    }
	//开启进程
    public fun bindService(activity: Activity,title:String,callback:(count:Int)->Unit){
        this.title = title
        this.callback = callback
        activity.bindService(Intent(activity, DBService::class.java),mServiceConnection, Context.BIND_AUTO_CREATE)
    }
    //解绑服务
    public fun unBinding(activity: Activity){
        activity.unbindService(mServiceConnection)
    }
}

到这里就结束了 是不是非常简单

Messenger 他的 底层还是通过AIDL实现，可以理解为谷歌为方便我们使用提供了简单的封装