对于大中型网站，为了增强用户体验，往往需要根据不同城市站点的用户推送或展现相应个性化的内容，如对于一些大型门户网站的新闻会有城市站点的功能，如果没有设置相应的城市站点，默认就是根据用户访问的IP地址的所在城市自动设置。本文主要通过自定义扩展IHttpModule接口，考虑到性能IP数据库主要采用QQwry纯真IP数据库，主要实现根据IP地址或地址段或IP所在城市进行自动跳转到指定页面的功能(支持Nginx作为前端反向代理服务器），该WebsiteSkip组件核心代码如下：

复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Xml;
using System.IO;
using System.Net;
using System.Text.RegularExpressions;
using NetOpen_System.Component.QQWry;

namespace NetOpen_System.Component
{
    public sealed class WebsiteSkipHttpModule : IHttpModule
    {
        #region IHttpModule 成员

        public void Dispose()
        {
        }

        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }

 
        #endregion

 
        void context_BeginRequest(object sender, EventArgs e)
        {
            try
            {

                //if (HttpContext.Current.Request.IsLocal)//忽略本地计算机请求
                //    return;

                //string ip = HttpContext.Current.Request.UserHostAddress;
                //string ip = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();
                string ip = string.Empty;
                if (HttpContext.Current.Request.ServerVariables["HTTP_X_REAL_IP"] != null)
                {
                    ip = HttpContext.Current.Request.ServerVariables["HTTP_X_REAL_IP"].ToString();
                }
                else if (HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null)
                {
                    ip = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
                }
                else if (HttpContext.Current.Request.ServerVariables["HTTP_VIA"] != null)
                {
                    ip = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
                }
                else
                {
                    ip = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();
                }

 
                QQWryLocator qqWry = new QQWryLocator(HttpContext.Current.Server.MapPath(@"~\IpData\qqwry.dat"));

                IPLocation ipaddress = qqWry.Query(ip);  //查询一个IP地址

                string ls_city = ipaddress.Country;
                string ls_urlfrom = string.Empty;
                string ls_urlto = string.Empty;
                string ls_url = HttpContext.Current.Request.Url.AbsoluteUri;
                string ls_useragentkeyword = string.Empty;

                ExcludeUserAgentMatchEngine Em = WebsiteSkipConfiguration.GetConfig().ExcludeUserAgents;

                if(Em.ExcludeUserAgentList.Count > 0)
                {
                    foreach (ExcludeUserAgent ua in Em.ExcludeUserAgentList)
                    {
                        if (HttpContext.Current.Request.UserAgent.Contains(ua.keyword))
                        {
                            return;
                        }
                    }
                }

                UrlMatchEngine pu = WebsiteSkipConfiguration.GetConfig().SkipedUrls;

                if (pu.UrlList.Count > 0)
                {
                    foreach (SkipedUrl sk in pu.UrlList)
                    {

                        if (ls_city.Contains(sk.IpCity))
                        {
                            if (sk.UrlFrom.Length > 0)
                            {
                                if (sk.UrlFrom.Contains(ls_url) && !ls_url.Contains(sk.OutKeyWord))
                                {
                                    if (sk.UrlTo.Length > 0)
                                    {
                                        HttpContext.Current.Response.Redirect(sk.UrlTo, true);
                                    }
                                    break;
                                }

                            }

                            break;
                        }
                    }
                }

                if (WebsiteSkipConfiguration.GetConfig().IpChecks.GetIpIn(ip))
                {
                    ls_urlfrom = WebsiteSkipConfiguration.GetConfig().IpChecks.UrlFrom.Trim();
                    ls_urlto = WebsiteSkipConfiguration.GetConfig().IpChecks.UrlTo.Trim();
                    if (ls_urlfrom.Length > 0)
                    {

                        if (ls_urlfrom.Contains(ls_url) && !ls_url.Contains(WebsiteSkipConfiguration.GetConfig().IpChecks.OutKeyWord))
                        {
                            if (ls_urlto.Length > 0)
                            {
                                HttpContext.Current.Response.Redirect(ls_urlto, true);
                            }

                        }

                   
                    }
                }

                
            }
            catch
            {

            }
        }
    }
}

在部署方面，非常简单主要利用IHttpModule接口并在Web.config中的HttpModule节点添加此组件的配置，访问限制或允许参数可以在NetOpen_SystemWebsiteSkip.cfg.xml进行设置，以下为一个简单的配置示例：

复制代码 代码如下:
<?xml version="1.0" encoding="utf-8" ?>
<NetOpen_System>
  <WebsiteSkip>
    <SkipedUrl>
    <add ipcity="温州" urlfrom="http://examplesite.com/Default.aspx,http://examplesite.com/,http://examplesite.cn/,http://www.examplesite.cn" urlto="http://wz.mainwebsite.pcom/index.aspx" outkeyword="math"/>
    <add ipcity="镇江" urlfrom="http://examplesite.com/Default.aspx,http://examplesite.com/,http://examplesite.cn/,http://www.examplesite.cn" urlto="http://jszj.mainwebsite.com/index.aspx" outkeyword="math"/>
    </SkipedUrl>
    <SkipedIP>
     <add ip1="220.186.0.0" ip2="220.186.255.255" urlfrom="http://examplesite.com/Default.aspx,http://examplesite.com/,http://examplesite.cn/,http://www.examplesite.cn" urlto="http://wz.mainwebsite.com/index.aspx" outkeyword="math"/>
    </SkipedIP>
    <ExcludeUserAgent>
     <add keyword="Baiduspider">
     <add keyword="Sosospider">
     <add keyword="Sogou web spider">
     <add keyword="Sogou inst spider">
     <add keyword="Sogou-Test-Spider">
     <add keyword="Sogou Orion spider">
     <add keyword="Gigabot">
     <add keyword="0JJJSpider">
     <add keyword="Sogou Pic Spider">
     <add keyword="Googlebot">
     <add keyword="Yeti/1.0">
    </ExcludeUserAgent>
  </WebsiteSkip>
  </WebsiteSkip>
</NetOpen_System>