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