: base(writer)
        ...{
            this.InnerWriter = writer;
        }
 
        public override void WriteAttribute(string name, string value, bool fEncode)
        ...{
            if (name == "action")
            ...{
                HttpContext context = HttpContext.Current;
 
                if (context.Items["ActionAlreadyWritten"] == null)
                ...{
                    value = context.Request.RawUrl;
                    context.Items["ActionAlreadyWritten"] = true;
                }
            }
 
            base.WriteAttribute(name, value, fEncode);
        }
    }
}

　不过要让这个Control Adaptor生效，还必须在Web项目中创建一个browser文件，例如“App_Browsers\Form.browser”，在里面写入如下代码：

<browsers>
  <browser refID="Default">
    <controlAdapters>
      <adapter controlType="System.Web.UI.HtmlControls.HtmlForm"
               adapterType="ajaxURLRewrite.FormRewriterControlAdapter" />
    </controlAdapters>
  </browser>
</browsers>
 

这样这个问题就完美解决了