通过HttpListener实现简单的Http服务

Posted 2020-08-06

使用HttpListener实现简单的Http服务

HttpListener提供一个简单的、可通过编程方式控制的 HTTP 协议侦听器.使用它可以很容易的提供一些Http服务，而无需启动IIS这类大型服务程序。使用HttpListener的方法流程很简单：主要分为以下几步

1. 创建一个HTTP侦听器对象并初始化
2. 添加需要监听的URI 前缀
3. 开始侦听来自客户端的请求
4. 处理客户端的Http请求
5. 关闭HTTP侦听器

例如：我们要实现一个简单Http服务，进行文件的下载，或者进行一些其他的操作，例如要发送邮件，使用HttpListener监听，处理邮件队列，避免在网站上的同步等待。以及获取一些缓存的数据等等行为

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Web;
using System.IO;
using Newtonsoft.Json;

namespace HttpListenerApp
{
    /// <summary>
    /// HttpRequest逻辑处理
    /// </summary>
    public class HttpProvider
    {

        private static HttpListener httpFiledownload;  //文件下载处理请求监听
        private static HttpListener httOtherRequest;   //其他超做请求监听

        /// <summary>
        /// 开启HttpListener监听
        /// </summary>
        public static void Init()
        {
            httpFiledownload = new HttpListener(); //创建监听实例
            httpFiledownload.Prefixes.Add("http://10.0.0.217:20009/FileManageApi/Download/"); //添加监听地址 注意是以/结尾。
            httpFiledownload.Start(); //允许该监听地址接受请求的传入。
            Thread ThreadhttpFiledownload = new Thread(new ThreadStart(GethttpFiledownload)); //创建开启一个线程监听该地址得请求
            ThreadhttpFiledownload.Start();

            httOtherRequest = new HttpListener();
            httOtherRequest.Prefixes.Add("http://10.0.0.217:20009/BehaviorApi/EmailSend/");  //添加监听地址 注意是以/结尾。
            httOtherRequest.Start(); //允许该监听地址接受请求的传入。
            Thread ThreadhttOtherRequest = new Thread(new ThreadStart(GethttOtherRequest));
            ThreadhttOtherRequest.Start();
        }

        /// <summary>
        /// 执行文件下载处理请求监听行为
        /// </summary>
        public static void GethttpFiledownload()
        {
            while (true)
            {
                HttpListenerContext requestContext = httpFiledownload.GetContext(); //接受到新的请求
                try
                {
                    //reecontext 为开启线程传入的 requestContext请求对象
                    Thread subthread = new Thread(new ParameterizedThreadStart((reecontext) =>      
                    {
                        Console.WriteLine("执行文件处理请求监听行为");

                        var request = (HttpListenerContext)reecontext;
                        var image =  HttpUtility.UrlDecode(request.Request.QueryString["imgname"]); //接受GET请求过来的参数；
                        string filepath = AppDomain.CurrentDomain.BaseDirectory + image;
                        if (!File.Exists(filepath))
                        {
                            filepath = AppDomain.CurrentDomain.BaseDirectory + "default.jpg";       //下载默认图片
                        }
                        using (FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read))
                        {
                            byte[] buffer = new byte[fs.Length];
                            fs.Read(buffer, 0, (int)fs.Length); //将文件读到缓存区
                            request.Response.StatusCode = 200;
                            request.Response.Headers.Add("Access-Control-Allow-Origin", "*");
                            request.Response.ContentType = "image/jpg"; 
                            request.Response.ContentLength64 = buffer.Length;
                            var output = request.Response.OutputStream; //获取请求流
                            output.Write(buffer, 0, buffer.Length);     //将缓存区的字节数写入当前请求流返回
                            output.Close();
                        }
                    }));
                    subthread.Start(requestContext); //开启处理线程处理下载文件
                }
                catch (Exception ex)
                {
                    try
                    {
                        requestContext.Response.StatusCode = 500;
                        requestContext.Response.ContentType = "application/text";
                        requestContext.Response.ContentEncoding = Encoding.UTF8;
                        byte[] buffer = System.Text.Encoding.UTF8.GetBytes("System Error");
                        //对客户端输出相应信息.
                        requestContext.Response.ContentLength64 = buffer.Length;
                        System.IO.Stream output = requestContext.Response.OutputStream;
                        output.Write(buffer, 0, buffer.Length);
                        //关闭输出流，释放相应资源
                        output.Close();
                    }
                    catch { }
                }
            }
        }

        /// <summary>
        /// 执行其他超做请求监听行为
        /// </summary>
        public static void GethttOtherRequest()
        {
            while (true)
            {
                HttpListenerContext requestContext = httOtherRequest.GetContext(); //接受到新的请求
                try
                {
                    //reecontext 为开启线程传入的 requestContext请求对象
                    Thread subthread = new Thread(new ParameterizedThreadStart((reecontext) =>
                    {
                        Console.WriteLine("执行其他超做请求监听行为");
                        var request = (HttpListenerContext)reecontext;
                        var msg = HttpUtility.UrlDecode(request.Request.QueryString["behavior"]); //接受GET请求过来的参数；
                        //在此处执行你需要进行的操作>>比如什么缓存数据读取，队列消息处理，邮件消息队列添加等等。

                        request.Response.StatusCode = 200;
                        request.Response.Headers.Add("Access-Control-Allow-Origin", "*");
                        request.Response.ContentType = "application/json";
                        requestContext.Response.ContentEncoding = Encoding.UTF8;
                        byte[] buffer = System.Text.Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(new { success = true, behavior = msg }));
                        request.Response.ContentLength64 = buffer.Length;
                        var output = request.Response.OutputStream;
                        output.Write(buffer, 0, buffer.Length);
                        output.Close();
                    }));
                    subthread.Start(requestContext); //开启处理线程处理下载文件
                }
                catch (Exception ex)
                {
                    try
                    {
                        requestContext.Response.StatusCode = 500;
                        requestContext.Response.ContentType = "application/text";
                        requestContext.Response.ContentEncoding = Encoding.UTF8;
                        byte[] buffer = System.Text.Encoding.UTF8.GetBytes("System Error");
                        //对客户端输出相应信息.
                        requestContext.Response.ContentLength64 = buffer.Length;
                        System.IO.Stream output = requestContext.Response.OutputStream;
                        output.Write(buffer, 0, buffer.Length);
                        //关闭输出流，释放相应资源
                        output.Close();
                    }
                    catch { }
                }
            }
        }
    }
}

调用方式：注意这里启动程序必须以管理员身份运行，因为上午的监听需要开启端口，所有需要以管理员身份运行。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HttpListenerApp
{
    class Program
    {
        static void Main(string[] args)
        {
            //开启请求监听
            HttpProvider.Init();
        }
    }
}

执行后的结果为：

这里通过一个简单的控制程序在里面使用HttpListener实现了简单的Http服务程序。里面有少量的线程和和异步处理，比如收到行为信息请求可以先返回给用户，让用户不用同步等待，就可以执行下一步操作，又比如实现的简单邮件服务器，将请求发给HttpListener接收到请求后就立即返回，交给队列去发送邮件。邮件的发送会出现延迟等待等情况出现，这样就不用等待。等等