在asp.net2.0中的urlmappings倒是非常好用，可惜暂不支持正则表达式，不过，好在如果用ihttpmodule的话

不管什么样的请求都会先经过ihttpmodule这样就为url重写提供了一个好机会：

下面是我写的一个ihttpmodule:

using system;
using system.web;

public class rewritemodule:ihttpmodule
{
 public rewritemodule()
 {
 }
    public override string tostring()
    {
        return this.gettype().tostring();
    }

void  ihttpmodule.dispose()
{
  
}
    private static system.xml.xmldocument ruledoc = null;
    private static system.xml.xmldocument getruleconfig(system.web.httpcontext app)
    {
        if (ruledoc == null)
        {
            ruledoc = new system.xml.xmldocument();
            ruledoc.load(app.server.mappath("~/rule.xml"));
        }
        return ruledoc;
    }
    public static string geturl(system.web.httpcontext cxt,string path)
    {
       
       system.xml.xmldocument doc = getruleconfig(cxt);
       system.xml.xmlnodelist lst= doc.getelementsbytagname("rewriterrule");
       string pat="";
       foreach (system.xml.xmlnode nd in lst)
       {
           system.xml.xmlnodelist sub = nd.childnodes[0].childnodes;
           foreach(system.xml.xmlnode chk in sub)
           {
               pat = "^" + chk.innertext+"$";
               system.text.regularexpressions.regex reg = new system.text.regularexpressions.regex(pat, system.text.regularexpressions.regexoptions.compiled | system.text.regularexpressions.regexoptions.ignorecase);
               if(reg.ismatch(path))
               {
                  return reg.replace(path, nd.childnodes[1].innertext);
               }
           }
       }
       return null;

    }
void  ihttpmodule.init(httpapplication context)
{
    context.beginrequest += delegate(object sender, eventargs e)
    {
       

        system.web.httpcontext cxt = context.context;
    
        if (cxt.request.contenttype != "image/pjpeg")
        {
            string type = cxt.request.contenttype.tolower();
            string path = cxt.request.path;
            string apppath = cxt.request.applicationpath;
            path = path.remove(0, apppath.length);
            path = "~" + path;
           
            string newurl = geturl(cxt, path.trimend().trimstart());
            if (newurl != null)
            {
                cxt.response.filter = new responsefilter(cxt.response.filter,cxt.request.path);
                cxt.response.write("请求的路径:" + path);
                cxt.response.write("<br>");
                cxt.response.write("转向的目的url：" + newurl);
                cxt.response.write("<br>");
                cxt.rewritepath(newurl);
               
               
               
            }//如果要求处理所有的请求时用到
            //else
            //{
            //    cxt.response.write(cxt.request.path + "<br>");
            //    cxt.response.write("你请求的资源不存在或无权访问！");
            //    cxt.response.flush();
            //    cxt.response.end();
            //}
        }
    
    };
   }

}

由于一旦进行了url重写，原先的webform中的action会发生改变，容易造成：请求的资源不存在问题

具体怎么样？各位dx看看就清楚了！！！

所有才有了这个responsefilter了，实现如下，

public class responsefilter:system.io.stream
{
        public responsefilter(system.io.stream sink,string _str)
  {
   _sink = sink;
   //
   // todo: 在此处添加构造函数逻辑
   //
            this.str = _str;
  }
    private string str = "";
  private system.io.stream _sink;
  private long _position;
  private system.text.encoding end=system.text.encoding.getencoding("gb18030");
  private system.text.stringbuilder  ooutput = new system.text.stringbuilder();
   // the following members of stream must be overriden.
  public override bool canread
  {
   get { return true; }
  }

  public override bool canseek
  {
   get { return true; }
  }

  public override bool canwrite
  {
   get { return true; }
  }

  public override long length
  {
   get { return 0; }
  }

  public override long position
  {
   get { return _position; }
   set { _position = value; }
  }

  public override long seek(long offset, system.io.seekorigin direction)
  {
   return _sink.seek(offset, direction);
  }

  public override void setlength(long length)
  {
   _sink.setlength(length);
  }

  public override void close()
  {
   _sink.close();
  }

  public override void flush()
  {
   _sink.flush();
  }

  public override int read(byte[] buffer, int offset, int count)
  {
   return _sink.read(buffer, offset, count);
  }

  // the write method actually does the filtering.
    public override void write(byte[] buffer, int offset, int count)
    {
        string szbuffer = system.text.utf8encoding.utf8.getstring(buffer, offset, count);
        string ap="action=\"";
        int pos=-1;
        if ((pos=szbuffer.indexof(ap) )!= -1)
        {
            int epos = szbuffer.indexof("\"", pos + ap.length+1);
            if (epos != -1)
            {
              szbuffer=  szbuffer.remove(pos + ap.length, epos - pos - ap.length);
            }

            szbuffer = szbuffer.insert(pos + ap.length, this.str);

            byte[] data = system.text.utf8encoding.utf8.getbytes(szbuffer);
            _sink.write(data, 0, data.length);
           
        }
        else
        {
            ooutput.append(szbuffer);
        }

        //下面的这一段可以用来修改<head></head>之间的内容；
        //regex oendfile = new regex("</head>", regexoptions.ignorecase|regexoptions.compiled);
        //if (oendfile.ismatch(szbuffer))
        //{
        //    //append the last buffer of data
        //    //附加上缓冲区中的最后一部分数据
        //    ooutput.append(szbuffer);
        //    //get back the complete response for the client
        //    //传回完整的客户端返回数据
        //    string szcompletebuffer = ooutput.tostring().tolower();
        //    int ipos = szcompletebuffer.indexof("<title>");
        //    int epos = szcompletebuffer.indexof("</title>",ipos+7);
        //    string sp = szcompletebuffer.substring(ipos+7, epos - ipos );
        //    szcompletebuffer = szcompletebuffer.remove(ipos+7,sp.length-7);
        //    szcompletebuffer = szcompletebuffer.insert(ipos + 7, "dhz");
        // //   szcompletebuffer = szcompletebuffer.replace(sp, "dhz");
        //    //no match, so write out original data
        //    //没有匹配，因此写入源代码
        //    byte[] data = system.text.utf8encoding.utf8.getbytes(szcompletebuffer);
        //    _sink.write(data, 0, data.length);
        //}
        //else
        //{
        //    ooutput.append(szbuffer);
        //}
    }
}

//////而重候规则呢则是用xml文件配置如下；

当然在web.config通过自定义配置节做也可以的

<?xml version="1.0" encoding="utf-8" ?>
<rules>
  <rewriterrule>
    <lookfors>
      <lookfor>~/(\d{4})/(\d{2})\.html</lookfor>
      <lookfor>~/(\d{4})/(\d{2})/</lookfor>
      <lookfor>~/(\d{4})/(\d{2})</lookfor>
      <lookfor>~/(\d{4})/(\d{2})/index.html</lookfor>
    </lookfors>
    <sendto>~/pro.aspx?year=$1&amp;month=$2</sendto>
  </rewriterrule>
  <rewriterrule>
    <lookfors>
      <lookfor>~/pc</lookfor>
    </lookfors>
    <sendto>~/test2.aspx</sendto>
  </rewriterrule>
</rules>
//这个规则写的不好，如第一个就可以用一个正则表达式来做。但是一时不知道怎么写好，好像要用到什么反捕获组的概念，正在思考这个东东！！