[英]Java custom event handler and listeners
I'm currently playing around with a Java implementation of Socket.io, available here: netty-socketio我目前正在使用 Socket.io 的 Java 实现,可在此处获得: netty-socketio
I've got the server up and running, and its receiving/sending messages nicely between client and server, but I need to have events trigger on certain messages being received, and that's where I'm confused.我已经启动并运行服务器,并且它在客户端和服务器之间很好地接收/发送消息,但是我需要在接收到某些消息时触发事件,这就是我感到困惑的地方。
Here's my code:这是我的代码:
server.addEventListener("message", clientData.class, new DataListener<clientData>() {
@Override
public void onData(SocketIOClient client, clientData data, AckRequest ackRequest) throws Exception {
System.out.println("Message from client: " + data.getMessage());
}
});
public class ClientData{
String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
Essentially what I'd like to happen is when a particular message is received from a client, I need a function within another class to run.基本上我想要发生的是当从客户端接收到特定消息时,我需要另一个类中的函数来运行。 I've spent the last two hours reading about
Observable
, Observer
, Interfaces
and event handlers, but I'm really not sure how to set this up.在过去的两个小时里,我一直在阅读
Observable
、 Observer
、 Interfaces
和事件处理程序,但我真的不知道如何设置它。
The library also makes mention of this DataListener
, but I've no idea what that is, as there's little documentation in the library.该库还提到了这个
DataListener
,但我不知道那是什么,因为库中的文档很少。
Any input or advice on this would be greatly appreciated.对此的任何意见或建议将不胜感激。
Let's say your class that raises the event is called A
.假设您引发事件的类称为
A
。 And the class that needs to listen for the event is called B
.需要监听事件的类称为
B
。 And the event is called SomeEvent
.该事件称为
SomeEvent
。
First, create an interface called SomeEventListener
:首先,创建一个名为
SomeEventListener
的接口:
public interface SomeEventListener {
void onSomeEvent ();
}
If there are arguments that you want to pass when the event occurs (typically something about the event), you can add it to the method.如果您想在事件发生时传递参数(通常是关于事件的一些内容),您可以将其添加到方法中。
Then in A
, you add a field:然后在
A
,添加一个字段:
private SomeEventListener listener;
and a method:和一个方法:
public void setSomeEventListener (SomeEventListener listener) {
this.listener = listener;
}
This way, B
can call setSomeEventListener
to set the listener.这样,
B
就可以调用setSomeEventListener
来设置监听器。
When the event occurs, A
should call当事件发生时,
A
应该调用
if (listener != null) listener.onSomeEvent ();
And that's all there is to A
!这就是
A
的全部内容!
In B
, you need to implement the interface:在
B
,您需要实现接口:
public class B implements SomeEventListener {
public void onSomeEvent () {
//do whatever you like when SomeEvent happens.
}
}
And you can listen for SomeEvent
like this:你可以像这样监听
SomeEvent
:
someInstanceOfA.setSomeEventListener (this);
And after this call, all the SomeEvent
raised by A
can be listened by B
!并且在这个调用之后,所有由
A
引发的SomeEvent
都可以被B
监听!
Using the Observable and Observer pattern, we can see that A
is an Observable and B
is an Observer.使用 Observable 和 Observer 模式,我们可以看到
A
是一个 Observable 而B
是一个观察者。
That's easy!这很容易!
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