作用

项目需现实推送消息的Service放入私有进程:push,找一种思路实现push来的消息由:push到:Main进程.这个demo将展示如何人初步实现项目这个需求

准备工作

了解Handle,Message原理http://www.jianshu.com/p/acaccfdf046b
了解AIDL机制原理:http://www.jianshu.com/p/c6a8e913efb3

利用Messenger信使来通信

1. 新建一个Messenger mMessenger,Service#onBind()返回mMessenger.getBinder();

2. MainActivity在bindService的回调中将IBinder强转为Messenger,Main拥有Service的Messenger,Main可以给Service发送指令了.

    private ServiceConnection mConn = new ServiceConnection()
    {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service)
    {
        mService = new Messenger(service);
        isConn = true;
        Message inactiveMessage = Message.obtain(null, MSG_SUM);
        inactiveMessage.replyTo = mMainMessenger;
        if (isConn) {
            //往服务端发激活消息
            try {
                mService.send(inactiveMessage);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
   
        }
   
    }
   
    @Override
    public void onServiceDisconnected(ComponentName name)
    {
        mService = null;
        isConn = false;
        mTvState.setText("disconnected!");
    }
    };
   

3. Service如何拥有Main的Messenger
   Main中新定义一个Messenger mMessenger

    private Messenger mMainMessenger = new Messenger(new Handler()
    {
    @Override
    public void handleMessage(Message msg)
    {
        switch (msg.what)
        {
            case MSG_SUM:
                Bundle bundle = (Bundle) msg.obj;
                mTvState.setText("=>" + bundle.getInt("result"));
                break;
        }
        super.handleMessage(msg);
    }
    });
   

   在绑定Service回调中,将一个激活Message的replyTo设置为mMessgener,Main将这个激活Message发送到Service.

   这样Service就能获取到Main的Messenger,通过它就能给Main发送消息了.

4. 数据传递
   数据传递使用Message携带,Message#obtain()的第三个参数可以依靠Bunder传输基本类型,非基本类型需要序列化.

Demo

https://github.com/xwpeng/TestMessengerMultiProcess.git