C# URL 重写与反重写

在URL重写中，最重要的莫过于IHttpModule接口了,先看下代码:
 

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

namespace YouXi.Components
{
    public class HttpModule : IHttpModule
    {

        #region IHttpModule 成员

        void IHttpModule.Dispose()
        {
            
        }

        void IHttpModule.Init(HttpApplication context)
       {
           //在页面读取开始时,这里每个页面都会先运行
           context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        void context_BeginRequest(object sender, EventArgs e)
        {
            //这儿处理url重写
            UrlRewriter.Rewriter();
        }
        #endregion
    }
}

 
UrlRewriter类，重写URL，并设置重写路径, 

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

namespace YouXi.Components
{
    public class UrlRewriter
    {
        /// <summary>
        /// url路径重写
        /// </summary>
        /// <param name="rawUrl"></param>
        public static void Rewriter()
        {
            //这儿处理url重写
            //string s_NewUrl = null; 

            //bool IsMatch = false;
            HttpRequest req = HttpContext.Current.Request;
            
            string rawUrl = req.Url.ToString();//.Remove(0, 7).ToLower();
            if (!rawUrl.EndsWith(".shtm"))
                return;

            if(CommonHelper.UrlReWriterHelper.Rewrite(ref rawUrl))
                HttpContext.Current.RewritePath(rawUrl);

        }
    }
}

 
重写初始化类
 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Xml;
using System.Text.RegularExpressions;

namespace CommonHelper
{
    public class UrlReWriterHelper
    {

        private static string configFile = "/Configs/UrlReWriter.Config";

        public List<UrlReWriterRule> Rules;

        private static UrlReWriterHelper Instance { get; set; }

        private bool _Enabled;
        private bool _Reverse;

        /// <summary>
        /// 反向匹配
        /// </summary>
        public bool Reverse
        {
            get { return _Reverse; }

        }
        /// <summary>
        /// 正向匹配
        /// </summary>
        public bool Enabled
        {
            get { return _Enabled; }
        }

        /// <summary>
        /// 初始化重写规则
        /// </summary>
        static UrlReWriterHelper()
        {
            Instance = new UrlReWriterHelper();
            Instance.Rules = new List<UrlReWriterRule>();

            string file = HttpContext.Current.Server.MapPath(configFile);
            XmlDocument xd = new XmlDocument();
            xd.Load(file);
            XmlElement xe = xd.DocumentElement;
            bool enabled = true;
            if (xe.Attributes["enabled"] != null)
            {
                enabled = Boolean.TryParse(xe.Attributes["enabled"].Value, out enabled);
            }
            Instance._Enabled = enabled;

            bool reverse = true;
            if (xe.Attributes["reverse"] != null)
            {
                reverse = Boolean.TryParse(xe.Attributes["reverse"].Value, out reverse);
            }
            Instance._Reverse = reverse;

            foreach (XmlNode xn in xe.ChildNodes)
            {
                if (xn.NodeType == XmlNodeType.Element)
                {
                    UrlReWriterRule re = new UrlReWriterRule(xn);
                    Instance.Rules.Add(re);
                }
            }

        }
        
        /// <summary>
        /// 按配置的规则进行路径重写并将最后值改写给参数,返回值表示是否进行重写
        /// </summary>
        /// <param name="rawUrl">可以根据此值进行重写操作</param>
        /// <returns></returns>
        public static bool Rewrite(ref string rawUrl)
        {
            if (string.IsNullOrEmpty(rawUrl.Trim()))
                return false;

            UrlReWriterHelper config = UrlReWriterHelper.Instance;
            if (!config.Enabled)
                return false;

            List<UrlReWriterRule> Rules = config.Rules;

            if (Rules == null || Rules.Count == 0)
                return false;

            foreach (UrlReWriterRule rule in Rules)
            {
                Regex r = new Regex(rule.Pattern, RegexOptions.IgnoreCase);
                if (r.IsMatch(rawUrl))
                {
                    string s_url = r.Replace(rawUrl, rule.Url);

                    rawUrl = s_url.Replace("/","/");
                    int start = rawUrl.IndexOf("/", 7);
                    if (start == 0)
                        return true;
                    rawUrl = rawUrl.Substring(start);
                    return true;
                }
            }
            return false;
        }
    }
}

 
UrlReWriterRule规则类,
 

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

namespace CommonHelper
{
    /// <summary>
    /// URL重写配置项
    /// </summary>
    public class UrlReWriterRule
    {
        #region
        private string _Pattern;
        private string _Url;
        private string _RePattern;
        private string _ReUrl;
        #endregion

        #region
        /// <summary>
        /// 反向重写后的路径
        /// </summary>
        public string ReUrl
        {
            get { return _ReUrl; }
        }

        /// <summary>
        /// 反向原始路径
        /// </summary>
        public string Repattern
        {
            get { return _RePattern; }
        }

        /// <summary>
        /// 正向重写后的路径
        /// </summary>
        public string Url
        {
            get { return _Url; }
        }

        /// <summary>
        ///  正向原始路径
        /// </summary>
        public string Pattern
        {
            get { return _Pattern; }
        }
        #endregion

        public UrlReWriterRule()
        {
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="xn">XML节点</param>
        public UrlReWriterRule(XmlNode xn)
        {
            try
            {
                if (xn.SelectSingleNode("pattern") != null)
                    _Pattern = xn.SelectSingleNode("pattern").InnerText;
                else if(xn.Attributes["pattern"]!=null)
                    _Pattern = xn.Attributes["pattern"].Value;

                if (xn.SelectSingleNode("url") != null)
                    _Url = xn.SelectSingleNode("url").InnerText;
                else if (xn.Attributes["url"] != null)
                    _Url = xn.Attributes["url"].Value;



                if (xn.SelectSingleNode("repattern") != null)
                    _RePattern = xn.SelectSingleNode("repattern").InnerText;
                else if (xn.Attributes["repattern"] != null)
                    _RePattern = xn.Attributes["repattern"].Value;


                if (xn.SelectSingleNode("reurl") != null)
                    _ReUrl = xn.SelectSingleNode("reurl").InnerText;
                else if (xn.Attributes["reurl"] != null)
                    _ReUrl = xn.Attributes["reurl"].Value;
            }
            catch (Exception e)
            {
                throw (e);
            }
        }
    }
}

 
UrlReWriter.Config 重写规则config文件
 

<?xml version="1.0" encoding="utf-8" ?>
<UrlReWriter enabled="true" reverse="false">

<!--链接到其他刚站的URL中转-->
    <url pattern="/go/(d+).shtm" url="/go/reurl.ashx?urlid=$1" 
    repattern="^/games/reurl.ashx?urlid=(d+)$" reurl="/games/$1.shtm"></url>

    <!--Tags页面-->
    <url pattern="/tags/([^/.]+).shtm" url="/go/TagGameList.aspx?tagName=$1"
    repattern="^/go/TagGameList.aspx?tagName=([wW+]+)$" reurl="/tags/$1.shtm"></url>

    <!--Tags页面-->
    <url pattern="/tags/([^/]+)/(d+).shtm" reurl="/tags/$1/$2.shtm">
        <url>
            <![CDATA[/go/TagGameList.aspx?tagName=$1&pageIndex=$2]]></url>
        <repattern><![CDATA[^/go/TagGameList.aspx?tagName=([^&]+)&(d+)$]]></repattern>        
    </url>
</UrlReWriter>