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如何使用HttpListener同时处理多个连接?

httplistener asynchronous c#

yossi · 技术社区 · 10 年前

在我构建的应用程序中,需要能够同时为多个客户端提供服务的Web服务器。
为此,我使用 HttpListener 对象用它 Async 方法\事件 BeginGetContext 和 EndGetContext .
在委托方法中,有一个调用要求侦听器重新开始侦听,并且它有效。。主要地

提供的代码是我在这里和那里找到的代码的混合,以及模拟数据处理瓶颈的延迟。

问题是,只有在最后一个连接被服务之后,它才开始管理下一个连接。。对我来说没用。

public class HtServer {


    public void startServer(){
        HttpListener HL = new HttpListener();
        HL.Prefixes.Add("http://127.0.0.1:800/");
        HL.Start();
        IAsyncResult HLC = HL.BeginGetContext(new AsyncCallback(clientConnection),HL);   
    }

    public void clientConnection(IAsyncResult res){
        HttpListener listener = (HttpListener)res.AsyncState;
        HttpListenerContext context = listener.EndGetContext(res);
        HttpListenerRequest request = context.Request;
        // Obtain a response object.
        HttpListenerResponse response = context.Response;
        // Construct a response. 
        // add a delay to simulate data process
        String before_wait = String.Format("{0}", DateTime.Now);
        Thread.Sleep(4000);
        String after_wait = String.Format("{0}", DateTime.Now);
        string responseString = "<HTML><BODY> BW: " + before_wait + "<br />AW:" + after_wait + "</BODY></HTML>";
        byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
        // Get a response stream and write the response to it.
        response.ContentLength64 = buffer.Length;
        System.IO.Stream output = response.OutputStream;
        // You must close the output stream.
        output.Write(buffer, 0, buffer.Length);
        output.Close();
        listener.BeginGetContext(new AsyncCallback(clientConnection), listener);
    }
}

编辑

    private static void OnContext(IAsyncResult ar)
    {
        var ctx = _listener.EndGetContext(ar);
        _listener.BeginGetContext(OnContext, null);

        Console.WriteLine(DateTime.UtcNow.ToString("HH:mm:ss.fff") + " Handling request");

        var buf = Encoding.ASCII.GetBytes("Hello world");
        ctx.Response.ContentType = "text/plain";

        // prevent thread from exiting.
        Thread.Sleep(3000);
        // moved these lines here.. to simulate process delay
        ctx.Response.OutputStream.Write(buf, 0, buf.Length);
        ctx.Response.OutputStream.Close();
        Console.WriteLine(DateTime.UtcNow.ToString("HH:mm:ss.fff") + " completed");
    }

输出为 enter image description here

2 回复 | 直到 10 年前

jgauffin 10 年前

好这是因为在处理完第一个上下文之后,就开始获取下一个上下文。不要那样做。直接获取下一个上下文:

public void clientConnection(IAsyncResult res){
    HttpListener listener = (HttpListener)res.AsyncState;
    HttpListenerContext context = listener.EndGetContext(res);

    //tell listener to get the next context directly.
    listener.BeginGetContext(clientConnection, listener);

    HttpListenerRequest request = context.Request;
    // Obtain a response object.
    HttpListenerResponse response = context.Response;
    // Construct a response. 
    // add a delay to simulate data process
    String before_wait = String.Format("{0}", DateTime.Now);
    Thread.Sleep(4000);
    String after_wait = String.Format("{0}", DateTime.Now);
    string responseString = "<HTML><BODY> BW: " + before_wait + "<br />AW:" + after_wait + "</BODY></HTML>";
    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
    // Get a response stream and write the response to it.
    response.ContentLength64 = buffer.Length;
    System.IO.Stream output = response.OutputStream;
    // You must close the output stream.
    output.Write(buffer, 0, buffer.Length);
    output.Close();
}

以下是我的示例代码,证明它有效(根据OP的请求更新):

class Program
{
    private static HttpListener _listener;

    static void Main(string[] args)
    {
        _listener = new HttpListener();
        _listener.Prefixes.Add("http://localhost/asynctest/");
        _listener.Start();
        _listener.BeginGetContext(OnContext, null);

        Console.ReadLine();
    }

    private static void OnContext(IAsyncResult ar)
    {
        var ctx = _listener.EndGetContext(ar);
        _listener.BeginGetContext(OnContext, null);

        Console.WriteLine(DateTime.UtcNow.ToString("HH:mm:ss.fff") + " Handling request");

        var buf = Encoding.ASCII.GetBytes("Hello world");
        ctx.Response.ContentType = "text/plain";

        // simulate work
        Thread.Sleep(10000);

        ctx.Response.OutputStream.Write(buf, 0, buf.Length);
        ctx.Response.OutputStream.Close();


        Console.WriteLine(DateTime.UtcNow.ToString("HH:mm:ss.fff") + " completed");
    }
}

生成:

enter image description here

这两个请求都开始直接处理。

为什么上述代码有效

HTTP有一种叫做流水线的东西。这意味着通过同一连接接收的所有请求必须以相同的顺序获得响应。然而,内置的HttpListener似乎不支持流水线,而是在处理第二个请求之前完成第一个请求的响应。因此,务必确保每个请求都通过新连接发送。

最简单的方法是在尝试代码时使用不同的浏览器。我做到了,正如你所见,我的两个请求都是同时处理的。

Aron 10 年前

请尝试此操作。。

这将使用异步编码来确保没有阻塞。阻塞意味着当线程休眠时,程序通常会“冻结”。通过使用此代码,您可以运行非阻塞,这意味着几乎不可能“冻结”应用程序。

public async Task handleClientConnection(HttpListener listener){
    HttpListenerContext context = await listener.GetContextAsync();
    var ret = handleClientConnection(listener);

    HttpListenerRequest request = context.Request;
    // Obtain a response object.
    HttpListenerResponse response = context.Response;
    // Construct a response. 
    // add a delay to simulate data process
    String before_wait = String.Format("{0}", DateTime.Now);
    await Task.Wait(4000);
    String after_wait = String.Format("{0}", DateTime.Now);
    string responseString = "<HTML><BODY> BW: " + before_wait + "<br />AW:" + after_wait + "</BODY></HTML>";
    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
    // Get a response stream and write the response to it.
    response.ContentLength64 = buffer.Length;
    using(System.IO.Stream output = response.OutputStream)
        output.Write(buffer, 0, buffer.Length);

    await ret;
}

public void startServer(){
    HttpListener HL = new HttpListener();
    HL.Prefixes.Add("http://127.0.0.1:800/");
    HL.Start();
    await handleClientConnection(HL);
}