标签：android blog http io 使用 strong ar for art
如果你需要你的service和其他进程通信，那么你可以使用一个Messenger来提供这个接口。
这种方法允许你在不使用 AIDL的情况下，进行跨进程通信IPC。
下面是一个如何使用 Messenger的小总结：
1. service实现一个 Handler 接收客户端每一次调用的回调。
2. Handler 用来创建一个Messenger对象，它是一个Handler的引用。
3. Messenger创建一个 IBinder，service从 onBind()中把它返回给客户端。
4. 客户端使用这个IBinder来实例化Messenger （service的Handler的引用），客户端使用它来向service发送Message对象。
5. service在它的Handler中接收每一个Message对象，在它的 handleMessage()方法中。
public class MessengerService extends Service
{
/** Command to the service to display a message */
static final int MSG_SAY_HELLO = 1;
/**
* Handler of incoming messages from clients.
*/
class IncomingHandler extends Handler
{
@Override
public void handleMessage(Message msg)
{
switch (msg.what)
{
case MSG_SAY_HELLO:
Toast.makeText(getApplicationContext(), "hello!",
Toast.LENGTH_SHORT).show();
break;
default:
super.handleMessage(msg);
}
}
}
/**
* Target we publish for clients to send messages to IncomingHandler.
*/
final Messenger mMessenger = new Messenger(new IncomingHandler());
/**
* When binding to the service, we return an interface to our messenger for
* sending messages to the service.
*/
@Override
public IBinder onBind(Intent intent)
{
Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT)
.show();
return mMessenger.getBinder();
}
}
注意 Handler中的 handleMessage() 方法是service接收到来的 Message并且决定做什么的地方。
客户端需要做的仅仅是创建一个基于service所返回的 IBinder的 Messenger，然后用 send()方法发送信息。
比如，这里有一个简单的activity和service绑定并且发送信息给service：
public class ActivityMessenger extends Activity
{
/** Messenger for communicating with the service. */
Messenger mService = null;
/** Flag indicating whether we have called bind on the service. */
boolean mBound;
/**
* Class for interacting with the main interface of the service.
*/
private ServiceConnection mConnection = new ServiceConnection()
{
public void onServiceConnected(ComponentName className, IBinder service)
{
// This is called when the connection with the service has been
// established, giving us the object we can use to
// interact with the service. We are communicating with the
// service using a Messenger, so here we get a client-side
// representation of that from the raw IBinder object.
mService = new Messenger(service);
mBound = true;
}
public void onServiceDisconnected(ComponentName className)
{
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
mService = null;
mBound = false;
}
};
public void sayHello(View v)
{
if (!mBound)
return;
// Create and send a message to the service, using a supported ‘what‘
// value
Message msg = Message
.obtain(null, MessengerService.MSG_SAY_HELLO, 0, 0);
try
{
mService.send(msg);
}
catch (RemoteException e)
{
e.printStackTrace();
}
}
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
@Override
protected void onStart()
{
super.onStart();
// Bind to the service
bindService(new Intent(this, MessengerService.class), mConnection,
Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop()
{
super.onStop();
// Unbind from the service
if (mBound)
{
unbindService(mConnection);
mBound = false;
}
}
}
注意这个例子并没有展示service如何响应客户端，如果你想要service响应，你需要在客户端中创建一个 Messenger。
然后当客户端接收到onServiceConnected()回调方法时，它会发送一个 Message到service，在它的send() 方法的replyTo参数中包含了客户端的Messenger。
标签：android blog http io 使用 strong ar for art
原文地址：http://www.cnblogs.com/dongweiq/p/3951301.html
