URL重写给 asp.net Ajax带来的问题

在使用了URL重写的页面，我们为了保证用户进行PostBack后页面的URL仍然是,我们原先展现给用户的链接，比如是list_1.html而不是list.aspx?page=1

我们需要使用app_browsers目录，存放浏览器定义文件，相关说明可以参考msdn：http://msdn2.microsoft.com/zh-cn/library/ms228122(vs.80).aspx

 

<!--

可在 <windir>\Microsoft.NET\Framework\<ver>\CONFIG\Browsers 中找到现有的浏览器定义

-->

<browsers>

  <browser refID="Default">

    <controlAdapters>

      <adapter controlType="System.Web.UI.HtmlControls.HtmlForm"

               adapterType="FormRewriterControlAdapter" />

    </controlAdapters>

  </browser>

</browsers>

 

 

代码如下：

public class FormRewriterControlAdapter : System.Web.UI.Adapters.ControlAdapter

    {

        protected override void Render(HtmlTextWriter writer)

        {

            if (HttpContext.Current.Request.RawUrl.Contains(".html"))

            {

                base.Render(new RewriteFormHtmlTextWriter(writer));

            }

            else

            {

                base.Render(writer);

            }

        }

    }

    public class RewriteFormHtmlTextWriter : HtmlTextWriter

    {

        public RewriteFormHtmlTextWriter(Html32TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer.InnerWriter;

        }



        public RewriteFormHtmlTextWriter(System.IO.TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer;

        }



        public override void WriteAttribute(string name, string value, bool fEncode)

        {

            if (name == "action")

            {

                if (HttpContext.Current.Items["ActionAlreadyWritten"] == null)

                {

                    value = HttpContext.Current.Request.RawUrl;

                    HttpContext.Current.Items["ActionAlreadyWritten"] = true;

                }

            }

            base.WriteAttribute(name, value, fEncode);

        }

    }

以上代码一直运行了很长时间，但是后来在使用asp.net Ajax是发现URL重写后的页面会出现错误，重新修改代码，排除Asp.net Ajax请求进行处理，代码如下：

public class FormRewriterControlAdapter : System.Web.UI.Adapters.ControlAdapter

    {

        protected override void Render(HtmlTextWriter writer)

        {

            if (HttpContext.Current.Request.RawUrl.Contains(".html"))

            {

                //取得asp.net Ajax请求标志

                var AsyncPost=HttpContext.Current.Request.Form["__ASYNCPOST"];

                if (AsyncPost=="true") //判断是否asp.net Ajax请求

                {

                    base.Render(writer);

                }

                else

                {

                    base.Render(new RewriteFormHtmlTextWriter(writer));

                }

            }

            else

            {

                base.Render(writer);

            }

        }

    }

    public class RewriteFormHtmlTextWriter : HtmlTextWriter

    {

        public RewriteFormHtmlTextWriter(Html32TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer.InnerWriter;

        }



        public RewriteFormHtmlTextWriter(System.IO.TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer;

        }



        public override void WriteAttribute(string name, string value, bool fEncode)

        {

            if (name == "action")

            {

                if (HttpContext.Current.Items["ActionAlreadyWritten"] == null)

                {

                    value = HttpContext.Current.Request.RawUrl;

                    HttpContext.Current.Items["ActionAlreadyWritten"] = true;

                }

            }

            base.WriteAttribute(name, value, fEncode);

        }

    }

后又经过调试发现是RewriteFormHtmlTextWriter的构造器有问题，没有包含htmlTextWriter类型的构造器，而使用了TextWriter类型构造器，导致页面结构错误出现null报错。再次调整代码如下：

public class FormRewriterControlAdapter : System.Web.UI.Adapters.ControlAdapter

    {

        protected override void Render(HtmlTextWriter writer)

        {

            if (HttpContext.Current.Request.RawUrl.Contains(".html"))

            {

                //使用过滤掉asp.net Ajax请求的方式避免错误

                //而后发现是RewriteFormHtmlTextWriter的构造器的问题，遂放弃方法

                //var AsyncPost=HttpContext.Current.Request.Form["__ASYNCPOST"];

                //if (AsyncPost=="true")

                //{

                //    base.Render(writer);

                //}

                //else

                //{

                //    base.Render(new RewriteFormHtmlTextWriter(writer));

                //}

                base.Render(new RewriteFormHtmlTextWriter(writer));

            }

            else

            {

                base.Render(writer);

            }

        }





    }

    public class RewriteFormHtmlTextWriter : HtmlTextWriter

    {

        //使用html 4.0方式的渲染器

        public RewriteFormHtmlTextWriter(HtmlTextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer.InnerWriter;

        }

        //使用html 3.2方式的渲染器，兼容老浏览器

        public RewriteFormHtmlTextWriter(Html32TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer.InnerWriter;

        }

        //其他方式浏览器，有可能引起null错误

        public RewriteFormHtmlTextWriter(System.IO.TextWriter writer)

            : base(writer)

        {

            this.InnerWriter = writer;

        }



        public override void WriteAttribute(string name, string value, bool fEncode)

        {



            if (name == "action")

            {

                if (HttpContext.Current.Items["ActionAlreadyWritten"] == null)

                {

                    value = HttpContext.Current.Request.RawUrl;

                    HttpContext.Current.Items["ActionAlreadyWritten"] = true;

                }

            }



            base.WriteAttribute(name, value, fEncode);

        }



    }

关于HtmlTextWriter和Html32TextWriter可以看一下这篇文章  http://www.cnblogs.com/Vegaslee/archive/2007/12/04/982723.html