如何从void函数返回数据? [英] How to return data from void function?

问题描述

因此，大约一周前，我问了一个有关activex和UDP的问题.在这里:

So, around a week ago I asked a question about activex and UDP. Here it is:

C#UDP套接字客户端和服务器

现在，我创建了两个应用程序，一个(发送方)通过UDP发送预定义的字符串.另一个是从网页调用的activex组件，它的线程在后台运行. UDP消息到达后，就完成了它的工作(写在数据库中，写在log.txt中，等等).

Now, I created two applications, one (the sender) to send pre-defined strings via UDP. The other is activex component that is called from a webpage, and it's thread is working in the background. Once an UDP message arrives, then it's doing it's stuff (writing in database, writing in log.txt, and so on).

我需要做的最后一件事是返回数据(如果是字符串或其他形式，还需要说一说).但是，activex中被调用的方法必须为空，因为如果将其设为字符串，则该线程将无法工作，并且只有第一条消息会到达.

The last thing i need is to return data (it's yet to be said if it will be string or something else). However, the method in the activex which is called must be a void, because if it's made to be string, the threading wont work, and only the first message will arrive.

我的问题是，该怎么做?如何从void函数返回数据?例如，Web应用程序现在正在像这样调用activex DLL:

My question is, how to do that? How to return data from a void function? For example, the web app now is calling the activex DLL like this:

    ClassLibrary1.Class1 activex = new ClassLibrary1.Class1();
    activex.StartThread();

然后StartThread()调用侦听线程，并且它在后台工作，一旦UDP消息到达，它就会像我上面所说的那样做一些事情.

And the StartThread() calls the listening thread and it's working in the background, and once UDP msg arrives, its doing some stuff like i said above.

我如何通过线程(事件)返回值，然后Web应用程序将捕获并使用它?

How can i return value with the threads (events) and the web app will catch it and use it?

非常感谢.

推荐答案

您可以使用事件(实现了Observable模式)来提醒任何侦听器新消息已到达:

You can use events (which implement the Observable pattern) to alert any listener that a new message has arrived:

public class NewMessageArgs : EventArgs
{
    public string Message { get; private set; }

    public NewMessageArgs(string message)
    {
        Message = message;
    }
}

public class ActiveXComponent
{
    public event EventHandler<NewMessageArgs> OnMessage;


    public void StartThread()
    {
        while (true)
        {
            //do stuff

            //raise "message received" event
            if (OnMessage != null)
                OnMessage(this, new NewMessageArgs("hi"));
        }
    }
}

然后您可以像这样收听这些事件:

You can then listen to these events like so:

ActiveXComponent activex = new ActiveXComponent();
activex.OnMessage += ProcessMessage;
activex.StartThread();

public void ProcessMessage(object sender, NewMessageArgs args)
{
    var msg = args.Message;
    //process
}

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