.NET下通过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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。