asp.net 使用页适配器和重写Render对全站输出的页面的HTML内容进行修改，不会错乱

两个比较重点的知识：

1.使用页适配器：http://www.cnblogs.com/sifang2004/archive/2006/05/31/414182.html

如果用新建一个pageBase：Page 来给所有页面继承，程序改动非常大，还有可能改少了。使用页适配器刚好可以达到可插拔的效果，功能又一样。

2.重写Render：http://www.cnblogs.com/mxw09/archive/2010/12/15/1906783.html

链接里的文章说的很清楚了，使用传统的法写会导致输出以后html内容顺序错乱，比如：Substitution控件，它生成的HTML总是跑到HTML最上面

功能：把站点输出的HTML以publicimg开头的字符串前面加上http://loaclhost:17100

页适配器配置文法：1.在WEB项目里新增App_Browsers文件夹，新增一个Default.browser文件，在<browsers>节点里新增

<browser refID="Default">

<controlAdapters>

<adapter controlType="System.Web.UI.Page"

adapterType="TestWeb.MyPageAdapter,TestWeb" />

</controlAdapters>

</browser>

代码如下：

namespace TestWeb{
public class MyPageAdapter : System.Web.UI.Adapters.PageAdapter
    {
        public string GetRenderHtml(HtmlTextWriter writer)
        {
            var Response = this.Page.Response;

            //Response.Output其实就是一个HttpWriter,Response.OutputStream其实就是HttpResponseStream,Object.ReferenceEquals (Response.Output,(Response.OutputStream as HttpResponseStream)._writer)为true

            BindingFlags bind = BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.IgnoreCase | BindingFlags.GetField;
            //因为HttpWriter._charBuffer这个字符数组的长度是1024，
            //所以推测，一旦某一段字符串超过1024就会创建一个IHttpResponseElement，
            //然后加入到HttpWriter._buffers,HttpWriter._buffers的每一个元素都实现了IHttpResponseElement接口,
            //具体类型可能是HttpResponseUnmanagedBufferElement，HttpSubstBlockResponseElement等类型
            ArrayList arr = (ArrayList)Response.Output.GetType().GetField("_buffers", bind).GetValue(Response.Output);

            Assembly systemWeb = Assembly.Load("System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a");
            Type type = systemWeb.GetType("System.Web.IHttpResponseElement");
            MethodInfo method = type.GetMethod("GetBytes");
            StringBuilder sb = new StringBuilder(5000);
            //遍历每一个buffer，获取buffer里存储的字符数组，然后转换为字符串
            for (int i = 0; i < arr.Count; i++)
            {
                byte[] buffer = (byte[])method.Invoke(arr[i], null);
                //使用当前编码得出已经存储到HttpWriter._buffers中的字符串
                sb.Append(Response.ContentEncoding.GetString(buffer));
            }
            //获取HttpWriter的字符数组缓冲区
            char[] charBuffer = (char[])Response.Output.GetType().GetField("_charBuffer", bind).GetValue(Response.Output);
            int charBufferLength = (int)Response.Output.GetType().GetField("_charBufferLength", bind).GetValue(Response.Output);
            int charBufferFree = (int)Response.Output.GetType().GetField("_charBufferFree", bind).GetValue(Response.Output);
            //charBufferLength - charBufferFree 等于字符数组缓冲区已经使用的字符数量
            for (int i = 0; i < charBufferLength - charBufferFree; i++)
            {
                sb.Append(charBuffer[i]);
            }
            string html = sb.ToString();
            return html;
        }
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);
            string html = GetRenderHtml(writer);
            html = GetNewImageUrl(html);
            this.Page.Response.ClearContent();
            this.Page.Response.Write(html);
        }
        public string GetNewImageUrl(string html)
        {
            string reg = "\"/publicimg/[^\"\"]*\"|\'/publicimg/[^\'\']*\'";
            reg += "|\\(/publicimg/[^\\(\\)]*\\)";
            return Regex.Replace(html, reg
                , new MatchEvaluator(GetNewImageUrlTag),
                                            RegexOptions.IgnoreCase
                                          | RegexOptions.Multiline
                                          | RegexOptions.IgnorePatternWhitespace
                                          | RegexOptions.Compiled);
        }
        private string GetNewImageUrlTag(Match match)
        {
            string quotesStart = match.Groups[0].Value[0].ToString();
            string quotesEnd = match.Groups[0].Value[match.Groups[0].Value.Length - 1].ToString();
            string imgName = match.Groups[0].Value.ToLower().Replace(quotesStart, "").Replace(quotesEnd, "");
            if (!string.IsNullOrEmpty(imgName) && imgName.StartsWith("/publicimg/"))
            {
                imgName = "http://loaclhost:17100/"+imgName;
            }
            return quotesStart + imgName + quotesEnd;
        }

    }
}