利用HttpListener创设简单的HTTP服务_C#

利用HttpListener创建简单的HTTP服务
using System;using System.Collections.Generic;using System.IO;using System.IO.Compression;using System.Linq;using System.Net;using System.Reflection;using System.Text;using System.Text.RegularExpressions;using System.Threading;using System.Threading.Tasks;public class HttpServer : IDisposable{    private const string NotFoundResponse = "<!doctype html><html><body>Resource not found</body></html>";    private readonly HttpListener httpListener;    private readonly CancellationTokenSource cts = new CancellationTokenSource();    private readonly string prefixPath;    private Task processingTask;    public HttpServer(string listenerUriPrefix)    {        this.prefixPath = ParsePrefixPath(listenerUriPrefix);        this.httpListener = new HttpListener();        this.httpListener.Prefixes.Add(listenerUriPrefix);    }    private static string ParsePrefixPath(string listenerUriPrefix)    {        var match = Regex.Match(listenerUriPrefix, @"http://(?:[^/]*)(?:\:\d+)?/(.*)");        if (match.Success)        {            return match.Groups[1].Value.ToLowerInvariant();        }        else        {            return string.Empty;        }    }    public void Start()    {        this.httpListener.Start();        this.processingTask = Task.Factory.StartNew(async () => await ProcessRequests(), TaskCreationOptions.LongRunning);    }    private async Task ProcessRequests()    {        while (!this.cts.IsCancellationRequested)        {            try            {                var context = await this.httpListener.GetContextAsync();                try                {                    await ProcessRequest(context).ConfigureAwait(false);                    context.Response.Close();                }                catch (Exception ex)                {                    context.Response.StatusCode = 500;                    context.Response.StatusDescription = "Internal Server Error";                    context.Response.Close();                    Console.WriteLine("Error processing HTTP request\n{0}", ex);                }            }            catch (ObjectDisposedException ex)            {                if ((ex.ObjectName == this.httpListener.GetType().FullName) && (this.httpListener.IsListening == false))                {                    return; // listener is closed/disposed                }                Console.WriteLine("Error processing HTTP request\n{0}", ex);            }            catch (Exception ex)            {                HttpListenerException httpException = ex as HttpListenerException;                if (httpException == null || httpException.ErrorCode != 995)// IO operation aborted                {                    Console.WriteLine("Error processing HTTP request\n{0}", ex);                }            }        }    }    private Task ProcessRequest(HttpListenerContext context)    {        if (context.Request.HttpMethod.ToUpperInvariant() != "GET")        {            return WriteNotFound(context);        }        var urlPath = context.Request.RawUrl.Substring(this.prefixPath.Length)            .ToLowerInvariant();        switch (urlPath)        {            case "/":                if (!context.Request.Url.ToString().EndsWith("/"))                {                    context.Response.Redirect(context.Request.Url + "/");                    context.Response.Close();                    return Task.FromResult(0);                }                else                {                    return WriteString(context, "Hello World!", "text/plain");                }            case "/favicon.ico":                return WriteFavIcon(context);            case "/ping":                return WritePong(context);        }        return WriteNotFound(context);    }    private static Task WritePong(HttpListenerContext context)    {        return WriteString(context, "pong", "text/plain");    }    private static async Task WriteFavIcon(HttpListenerContext context)    {        context.Response.ContentType = "image/png";        context.Response.StatusCode = 200;        context.Response.StatusDescription = "OK";        using (var stream = File.Open("icon.png", FileMode.Open))        {            var output = context.Response.OutputStream;            await stream.CopyToAsync(output);        }    }    private static Task WriteNotFound(HttpListenerContext context)    {        return WriteString(context, NotFoundResponse, "text/plain", 404, "NOT FOUND");    }    private static async Task WriteString(HttpListenerContext context, string data, string contentType,        int httpStatus = 200, string httpStatusDescription = "OK")    {        AddCORSHeaders(context.Response);        AddNoCacheHeaders(context.Response);        context.Response.ContentType = contentType;        context.Response.StatusCode = httpStatus;        context.Response.StatusDescription = httpStatusDescription;        var acceptsGzip = AcceptsGzip(context.Request);        if (!acceptsGzip)        {            using (var writer = new StreamWriter(context.Response.OutputStream, Encoding.UTF8, 4096, true))            {                await writer.WriteAsync(data).ConfigureAwait(false);            }        }        else        {            context.Response.AddHeader("Content-Encoding", "gzip");            using (GZipStream gzip = new GZipStream(context.Response.OutputStream, CompressionMode.Compress, true))            using (var writer = new StreamWriter(gzip, Encoding.UTF8, 4096, true))            {                await writer.WriteAsync(data).ConfigureAwait(false);            }        }    }    private static bool AcceptsGzip(HttpListenerRequest request)    {        string encoding = request.Headers["Accept-Encoding"];        if (string.IsNullOrEmpty(encoding))        {            return false;        }        return encoding.Contains("gzip");    }    private static void AddNoCacheHeaders(HttpListenerResponse response)    {        response.Headers.Add("Cache-Control", "no-cache, no-store, must-revalidate");        response.Headers.Add("Pragma", "no-cache");        response.Headers.Add("Expires", "0");    }    private static void AddCORSHeaders(HttpListenerResponse response)    {        response.Headers.Add("Access-Control-Allow-Origin", "*");        response.Headers.Add("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");    }    private void Stop()    {        cts.Cancel();        if (processingTask != null && !processingTask.IsCompleted)        {            processingTask.Wait();        }        if (this.httpListener.IsListening)        {            this.httpListener.Stop();            this.httpListener.Prefixes.Clear();        }    }    public void Dispose()    {        this.Stop();        this.httpListener.Close();        using (this.cts) { }        using (this.httpListener) { }    }}