Question

我一直在寻找HttpListenter的东西：

http://msdn.microsoft.com/en-us/library/system.net.httplistener.aspx

它在标准控制台应用程序上运行良好，但我正在尝试将其作为Windows服务运行。应用程序日志显示，当服务启动时，它在HttpListener.Start（）方法上失败。我很难过为什么会发生这种情况。

这是课程（这里概念质量证明：）

public class Server
{
    public Server()
    {
        var thread = new Thread((Start));
        thread.Start();
    }

    public static void Start()
    {
        while(Listen())
        {
        }
    }

    private static bool Listen()
    {
        var prefixes = new[] {"http://192.168.0.7/"};

        if (!HttpListener.IsSupported)
        {
            Console.WriteLine ("Windows XP SP2 or Server 2003 is required to use the HttpListener class.");
            return false;
        }
        // URI prefixes are required, 
        // for example "http://contoso.com:8080/index/".
        if (prefixes == null || prefixes.Length == 0)
          throw new ArgumentException("prefixes");

        // Create a listener.
        HttpListener listener = new HttpListener();

        // Add the prefixes. 
        foreach (string s in prefixes)
        {
            listener.Prefixes.Add(s);
        }

        listener.Start();   //THIS FAILS IN WINDOWS SERVICE AS LOCAL SYSTEM

        //Console.WriteLine("Listening...");
        //// Note: The GetContext method blocks while waiting for a request. 
        //HttpListenerContext context = listener.GetContext();
        //HttpListenerRequest request = context.Request;
        //// Obtain a response object.
        //HttpListenerResponse response = context.Response;
        //// Construct a response. 
        //string responseString = "<HTML><BODY> " + DateTime.Now + "</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;
        //output.Write(buffer,0,buffer.Length);
        //// You must close the output stream.
        //output.Close();
        //listener.Stop();

        return true;
    }

}

相关日志：错误：

Application: Stout.Workers.Service.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Net.HttpListenerException
Stack:
   at System.Net.HttpListener.Start()
   at Stout.Workers.Service.Server.Listen()
   at Stout.Workers.Service.Server.Start()
   at System.Threading.ThreadHelper.ThreadStart_Context(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Threading.ThreadHelper.ThreadStart()

错误：

Faulting application name: Stout.Workers.Service.exe, version: 0.0.0.0, time stamp: 0x50d0cd99
Faulting module name: KERNELBASE.dll, version: 6.2.9200.16451, time stamp: 0x50988950
Exception code: 0xe0434352
Fault offset: 0x00014b32
Faulting process id: 0x1e70
Faulting application start time: 0x01cddd5bb3e8500b
Faulting application path:     C:\Users\Chad\Dropbox\Personal\Projects\Stout\Stout\Workers\Service\bin\Debug\Stout.Workers.Service.exe
Faulting module path: C:\Windows\SYSTEM32\KERNELBASE.dll
Report Id: f1aa9986-494e-11e2-be9b-685d43b0551c
Faulting package full name: 
Faulting package-relative application ID:

的信息：

Fault bucket , type 0
Event Name: CLR20r3
Response: Not available
Cab Id: 0

Problem signature:
P1: stout.workers.service.exe
P2: 0.0.0.0
P3: 50d0cd99
P4: System
P5: 4.0.30319.18016
P6: 505702c9
P7: 206c
P8: 5c
P9: System.Net.HttpListenerException
P10:

Answer 1

我猜你试图在听众身上接受多个请求。如果仔细阅读代码，您将发现实例化无限数量的侦听器，而不是创建单个侦听器来处理多个调用。

您实际获得的异常是StackOverflowException（唯一无法用try-catch块捕获的异常）无论您做什么，应用程序都会中断。

删除你的while循环（只需调用一次Listen）并尝试在Listen方法中使用以下方法。

HttpListener listener = new HttpListener();
//add your prefixes here
listener.Start();
AsyncCallback processRequest = delegate(IAsyncResult result)
{
    //set the listener to listen for next request
    listener.BeginGetContext(processRequest, listener);
    HttpListenerContext context = listener.EndGetContext(result);
    //Your code to handle the request here
}

listener.BeginGetContext(processRequest, listener);

这会使用单个HttpListener

创建您要查找的循环

希望这有帮助

更新：如果您取消注释请求处理代码，您将注意到，因为您在调用listener.GetContext()时阻塞线程并且侦听器挂起直到它收到请求，因此不会发生异常Listen方法不会返回。通过调用listener.Start()并返回true，您将以非常快的速率循环，从而创建许多侦听器。

您的代码可能会以这种方式工作，但效率很低，因为您必须为每个请求创建一个侦听器。最好让一个侦听器异步处理所有请求，因为如果你的一个请求需要10秒钟来执行你的循环，那么在你响应请求客户端之前不会创建另一个监听器。

在Windows服务启动时，HttpLisenter Start方法失败

1 个答案: