如何使用 C# 从 SignalR 客户端中的 Hub 类接收广播消息？

Question

我有一个场景，其中一个客户端正在向 Hub 类方法 AddMessage 发送请求，该方法又应该将该消息广播给所有客户端，包括发起它的客户端。

问题是我可以从客户端调用 Hub 方法AddMessage，如下面的代码所示，但是我找不到在客户端上处理广播消息的方法，该消息在Hub 类使用以下行。

Clients.All.NotifyMessageToClients(name, message);

SignalR 集线器类

using System;
using Microsoft.AspNet.SignalR;
using System.Threading.Tasks;

public class SignalRChatHub : Hub
{
    public void AddMessage(string name, string message)
    {
        // Following call is supposed to notify all clients with passed parameters. 
        // They could have a method called NotifyMessageToClients to fetch the broadcasted message

        Clients.All.NotifyMessageToClients(name, message); 
    }
}

SignalR 客户端

using System;
using Microsoft.AspNet.SignalR.Client;

public partial class Default : System.Web.UI.Page
{
    HubConnection hubConnection;
    IHubProxy stockTickerHubProxy;

    public Default()
    {
        hubConnection = new HubConnection("http://localhost:6898/");
        stockTickerHubProxy = hubConnection.CreateHubProxy("SignalRChatHub");
    }

    async public void SendAddNotification(string msgFrom, string msg)
    {
        // Following line calls Addmessage method in SignalRChatHub class
        await stockTickerHubProxy.Invoke("Addmessage", "Ajendra", "Hello StackOverflow");
    }

    // I might need the method NotifyMessageToClients here... to receive broadcasted message
}

我对如何在 jQuery 中实现相同的功能有了一些想法，但在 C# 中却没有，方法是像上面那样创建一个客户端。我将如何实现这一目标？

如果上述方法在任何方面都没有意义，请向我推荐正确的方法。

Answer 1

你需要像这样监听来自服务器的事件：

public partial class Default : System.Web.UI.Page
{
    HubConnection hubConnection;
    IHubProxy stockTickerHubProxy;

    public Default()
    {
        hubConnection = new HubConnection("http://localhost:6898/");
        stockTickerHubProxy = hubConnection.CreateHubProxy("SignalRChatHub");

        // listen to server events...
        // n is "name" and m is "message", but you can change to "a" and "b" or anything else...
        stockTickerHubProxy.On<string, string>("NotifyMessageToClients", (n, m) =>
        {
            Console.WriteLine("Message received from server. Name: {0} | Message: {1}", n, m);
        });

    }

    // "async" methods should return Task instead of void....
    // unless they are event handlers for UI applications...
    public async Task SendAddNotification(string msgFrom, string msg)
    {
        // first, start the connection...
        await stockTickerHubProxy.Start();
        // Following line calls Addmessage method in SignalRChatHub class
        await stockTickerHubProxy.Invoke("Addmessage", "Ajendra", "Hello StackOverflow");

        // you don't stop the connection, otherwise you won't be able to receive calls from the server
    }

}

...如果您需要更新 WPF 中的 UI，例如，您应该像这样实现您的事件：

stockTickerHubProxy.On<string, string>("NotifyMessageToClients", (a,b) => 
    Dispatcher.InvokeAsync(() =>
        {
            // update UI...
            textBox.Text += string.Format("Name: {0} | Message: {1}", a, b);
        })
);

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我建议阅读this guide 了解更详细的信息。