Android应用跨进程通信

AIDL and Messenger

自定义Binder类

图1

代码

服务端

public class MyBinder extends Binder
{
    public int getCount()
    {
        return count;
    }
}

private MyBinder binder = new MyBinder();

@Override
public IBinder onBind(Intent intent)
{
return binder;
}

客户端

MyBinder binder;

private ServiceConnection conn = new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName name,
 IBinder service)
{
binder = (BindService.MyBinder) service; 
}
};



bindService(intent, conn, Service.BIND_AUTO_CREATE);


binder.getCount();

AIDL

图2

代码

服务端

public class MyService extends IService.Stub
{
    public int getCount()
    {
        return count;
    }
}

private MyBinder myService = new MyBinder();

@Override
public IBinder onBind(Intent intent)
{
return myService;
}

客户端

IService mService;

private ServiceConnection conn = new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName name,
 IBinder service)
{
mService = IService.Stub.asInterface(service);
}
};



bindService(intent, conn, Service.BIND_AUTO_CREATE);


mService.getCount();

Messenger

图3

代码

服务端

private final Handler mHandler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
    byte[] data = response.getData().getByteArray("request");
    .........
    response.replyTo.send(reply);
  }
};


private Messenger mMessenger = new Messenger(mHandler);


public IBinder onBind(Intent intent) {
  return mMessenger.getBinder();
}

客户端

public Handler mHandler = new Handler() {
  public void handleMessage(Message msg) {
    switch (msg.what) {
      case END_SERVM_DONE:                 
      break;    
      default:
      break;
    }}};

private Messenger mSvcModeMessenger = new Messenger(mHandler);

public void onServiceConnected(ComponentName, IBinder service )
{
  mServiceMessenger = new Messenger(service);
}

void invokeOemRilRequestRaw(byte[] data, Message response) {
  response.setData(req);
  response.replyTo = mSvcModeMessenger;
  mServiceMessenger.send(response);
}

总结

自定义Binder类不属于跨进程通信，属于同进程通信，归根结底三种通信方式都是要用到Binder。
自定义Binder传递的就是同一个Binder对象的引用。
AIDL是通过底层的Binder机制进行通信
Messenger则封装了Hander，最本质还是IBinder对象，使用起来类似线程中的Hander通信。
两种跨进程通信本质是一样的，都是通过Binder来传递。