Url重写小例

时间：2011-05-13 来源：Mike Corleone

1.IHttpModule接口实现:

namespace AspNetUnleashed
{
    public class UrlRemapper : IHttpModule
    {
        public void Init(HttpApplication app)
        {
            app.BeginRequest += new EventHandler(app_BeginRequest);
        }

        public void app_BeginRequest(Object s, EventArgs e)
        {
            // Get HTTP Context
            HttpApplication app = (HttpApplication)s;
            HttpContext context = app.Context;

            // Get current URL
            string currentUrl = context.Request.AppRelativeCurrentExecutionFilePath;
            
            // Get URL Mappings
            XmlDocument urlMappings = GetUrlMappings(context);

            // Compare current URL against each URL from mappings file
            XmlNodeList nodes = urlMappings.SelectNodes("//add");
            foreach (XmlNode node in nodes)
            {
                string url = node.Attributes["url"].Value;
                string mappedUrl = node.Attributes["mappedUrl"].Value;
                if (Regex.Match(currentUrl, url, RegexOptions.IgnoreCase).Success)
                    context.RewritePath(mappedUrl);
            }
        }

        private XmlDocument GetUrlMappings(HttpContext context)
        {
            XmlDocument urlMappings = (XmlDocument)context.Cache["UrlMappings"];
            if (urlMappings == null)
            {
                urlMappings = new XmlDocument();
                string path = context.Server.MapPath("~/UrlMappings.config");
                urlMappings.Load(path);
                CacheDependency fileDepend = new CacheDependency(path);
                context.Cache.Insert("UrlMappings", urlMappings, fileDepend);

            }
            return urlMappings;
        }

        public void Dispose() { }

    }
}

BeginRequest 事件处理程序从名为UrlMappings.config的XML配置文件中得到一个Url重映射列表。XML配置文件 
UrlMappings.config中的内容缓存在服务器端内存中，知道硬盘上的UrlMappings.config被修改之后再次载入。
接下来，该模块使用从XML配置文件中获得的重映射条目，并使用正则进行匹配，如果成功，使用 context.RewritePath方法
把当前路径映射为重映射路径。

2.UrlMappings.config配置文件:
<?xml version="1.0"?>
<urlMappings>
  <add 
    url="~/Home.aspx"
    mappedUrl="~/Default.aspx" />
  <add 
    url="/Products/.*" 
    mappedUrl="~/Products/Default.aspx" />
</urlMappings>

3.Web.config:

<system.web>
        <httpModules>
            <add name="UrlRemapper" type="AspNetUnleashed.UrlRemapper"/>
                </httpModules>
</system.web>