Java 自定义事件处理程序和侦听器 [英] Java custom event handler and listeners

问题描述

我目前正在使用 Socket.io 的 Java 实现，可在此处获得:netty-socketio

I'm currently playing around with a Java implementation of Socket.io, available here: netty-socketio

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.

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.

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;
    }

}

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.我在过去的两个小时里阅读了关于 Observable、Observer、Interfaces 和事件处理程序，但我真的不知道如何设置到此为止.

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. 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.

图书馆还提到了这个 DataListener，但我不知道那是什么，因为图书馆里的文档很少.

The library also makes mention of this DataListener, but I've no idea what that is, as there's little documentation in the library.

对此的任何意见或建议将不胜感激.

Any input or advice on this would be greatly appreciated.

推荐答案

假设引发事件的类称为 A.而需要监听事件的类叫做B.该事件称为SomeEvent.

Let's say your class that raises the event is called A. And the class that needs to listen for the event is called B. And the event is called SomeEvent.

首先，创建一个名为SomeEventListener的接口:

First, create an interface called SomeEventListener:

public interface SomeEventListener {
    void onSomeEvent ();
}

如果你想在事件发生时传递参数(通常是关于事件的一些东西)，你可以将它添加到方法中.

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.

然后在 A 中，添加一个字段:

Then in A, you add a field:

private SomeEventListener listener;

和一个方法:

public void setSomeEventListener (SomeEventListener listener) {
    this.listener = listener;
}

这样B就可以调用setSomeEventListener来设置监听器.

This way, B can call setSomeEventListener to set the listener.

当事件发生时，A应该调用

When the event occurs, A should call

if (listener != null) listener.onSomeEvent ();

这就是 A 的全部内容！

And that's all there is to A!

在B中，需要实现接口:

public class B implements SomeEventListener {
    public void onSomeEvent () {
        //do whatever you like when SomeEvent happens.
    }
}

你可以像这样监听SomeEvent:

someInstanceOfA.setSomeEventListener (this);

并且在这个调用之后，所有A引发的SomeEvent都可以被B监听！

And after this call, all the SomeEvent raised by A can be listened by B!

使用 Observable 和 Observer 模式，我们可以看到 A 是一个 Observable，B 是一个 Observer.

Using the Observable and Observer pattern, we can see that A is an Observable and B is an Observer.

这很简单！

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