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:///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>