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，可在此处获取： netty-socketio

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

我已经启动并运行了服务器，它在客户端和服务器之间很好地接收/发送消息，但我需要在某些消息上触发事件被收到，这就是我困惑的地方。

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收到特定消息时，我需要在另一个类中运行一个函数。我花了最近两个小时阅读 Observable ， Observer ，接口和事件处理程序，但我真的不知道如何设置它。

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.

该库还提到了这个 DataListener ，但是我不知道那是什么，因为那里几乎没有库中的文档。

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.

谢谢

推荐答案

假设您提升事件的类名为 A 。需要监听事件的类称为 B 。该事件被称为 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：

public interface SomeEventListener {
    void onSomeEvent ();
}

如果事件发生时你想传递参数（通常是关于事件），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;

和方法：

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

这样， B 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 ！

在 B 中，您需要实现界面：

In B, you need to implement the interface:

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

你可以听 SomeEvent 是这样的：

someInstanceOfA.setSomeEventListener (this);

此次通话后，所有 SomeEvent 由 A 筹集的 B ！

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而 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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