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阿兔在线工具。
