Android跨程序通訊有很多種方式, 具體的大家百度一下就知道了. AIDL就是其中一種;

本文介紹AIDL系統輕量封裝Messager的使用.

涉及到的類

1.服務端編寫

class RemoteService : Service() {

    val
 
 remoteHandler: Handler = object : Handler() {
        override fun handleMessage(msg: Message) {
            super.handleMessage(msg)

            //注意此處, 必須的設定, 否則自定義的MsgBean類, ClassNotFoundException異常
            msg.data.classLoader = RemoteService.javaClass.classLoader

            val bean:MsgBean = msg.data.getParcelable<MsgBean>("data"
 
)

            if (msg.what == 3) {
                //測試死迴圈, 不會出現anr
                Thread.sleep(10_000)
            }

            //收到訊息後, 可以通過replyTo物件, 回覆客戶端.
            msg.replyTo?.let {

                //java.lang.RuntimeException: Can't marshal callbacks across processes.
//                it.send(Message.obtain(null) {
 

//                    L.e("runnable")
//                })

                sendText(it, 10_001, "服務端已收到訊息.${msg.what}")
            }
        }
    }

    private fun sendText(messenger: Messenger, what: Int, text: String) {
        messenger.send(Message.obtain(null, what).apply {
            replyTo = remoteMessenger //用來答覆的Messenger
            data = Bundle().apply {
                putParcelable("data", MsgBean(text)) //資料建議放在 Bundle中
            }
        })
    }

    private val remoteMessenger: Messenger

    init {
        remoteMessenger = Messenger(remoteHandler)
    }

    override fun onBind(p0: Intent?): IBinder {
        return remoteMessenger.binder
    }
}

幾點需要注意的:
1. 靜態資料在服務端修改後, 客戶端獲取不到修改後的值
2. 自定義的資料, 儘量使用 Bundle 包一層
3. Bundle需要設定classLoader, 否則會出現ClassNotFoundException

不要忘了在AndroidManifest.xml宣告:

<service
   android:name=".RemoteService"
   android:process=":remote"/>

如果android:process的名字, 有:號, 則這個程序和主程序是 父子關係 否則就是 兄弟關係

2.客戶端編寫

基礎的物件宣告:

val localHandler = object : Handler() {
    override fun handleMessage(msg: Message) {
        super.handleMessage(msg)
        L.e("客戶端: handleMessage ->${RemoteService.test_static_data} ${msg.what} ${msg.obj}")

        msg.data.classLoader = classLoader //注意:同樣的設定

        showText("收到服務端訊息:${RemoteService.test_static_data} ${msg.what} ${msg.obj} ${msg.data.getParcelable<MsgBean>("data")}")
    }
}

val localMessenger = Messenger(localHandler)

var remoteMessenger: Messenger? = null

啟動服務端:

val remoteServiceIntent = Intent(this, RemoteService::class.java)
val remoteCon = object : ServiceConnection {
    override fun onServiceDisconnected(p0: ComponentName?) {
        L.e("call: onServiceDisconnected -> $p0")

        showText("onServiceDisconnected_${p0}")

        remoteMessenger = null
    }

    override fun onServiceConnected(p0: ComponentName?, p1: IBinder?) {
        L.e("call: onServiceConnected -> $p0 $p1")
        showText("onServiceConnected_${p0}")

        remoteMessenger = Messenger(p1)
        sendText(1, "客戶端連線成功...")
    }
}
bindService(remoteServiceIntent, remoteCon, Service.BIND_AUTO_CREATE)

傳送訊息:

private fun sendText(what: Int, text: String) {
  remoteMessenger?.send(Message.obtain(null, what).apply {
      replyTo = localMessenger
      data = Bundle().apply {
          putParcelable("data", MsgBean(text))  //用Bundle包一層
      }
  })
}

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