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

/// <summary>
///IHttpHandler 接口实现类
/// </summary>
public class OwnHttpHandler : IHttpHandler
{
    #region IHttpHandler 成员

    /// <summary>
    /// 当前处理器是否还可以被另一个请求重复使用
    /// </summary>
    public bool IsReusable
    {
        get { return true; }
    }

    /// <summary>
    /// 对请求响应时，实际执行的代码
    /// </summary>
    /// <param name="context"></param>
    public void ProcessRequest(HttpContext context)
    {
        //这边为方便演示直接往集合添加规则，实际应用可考虑将规则写到配置文件中再读取
        Dictionary<string, string> rules = new Dictionary<string, string>();
        rules.Add(@"^/news/(\w+)\.aspx", "/news.aspx?t=$1");
        rules.Add(@"^/soft/(\w+)\.aspx", "/soft.aspx?t=$1");
        rules.Add(@"^/music/(\w+)\.aspx", "/music.aspx?t=$1");

        foreach (KeyValuePair<string, string> rule in rules)
        {
            Match match = Regex.Match(context.Request.Path, rule.Key, RegexOptions.IgnoreCase);
            if (match.Success)
            {
                string sendToUrl = Regex.Replace(context.Request.Path, rule.Key, rule.Value, RegexOptions.IgnoreCase);
                string path = sendToUrl;//虚拟路径
                string querystring = string.Empty;//查询参数
                if (sendToUrl.IndexOf("?") != -1)
                {
                    path = sendToUrl.Substring(0, sendToUrl.IndexOf("?"));
                    querystring = sendToUrl.Substring(sendToUrl.IndexOf("?") + 1);
                }

                context.Server.Execute(path + "?" + querystring);

                return;
            }
        }

        context.Response.Write("404:页面未找到！");
    }

    #endregion
}

<httpHandlers>
  <add verb="*" path="/news/*.aspx" type="OwnHttpHandler" />
  <add verb="*" path="/soft/*.aspx" type="OwnHttpHandler" />
  <add verb="*" path="/music/*.aspx" type="OwnHttpHandler" />
</httpHandlers>