在Module中使用自定义过滤器，来统一对站内所有请求响应的输出内容进行采集或更改。

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
using System.Web;

    /**//// <summary>
    /// 定义原始数据EventArgs,便于在截获完整数据后，由事件传递数据
    /// </summary>
    public class RawDataEventArgs : EventArgs
    {
        private string sourceCode;

        public RawDataEventArgs(string SourceCode)
        {
            sourceCode = SourceCode;
        }
        public string SourceCode
        {
            get { return sourceCode; }
            set { sourceCode = value; }
        }
    }

//自定义过滤器
    public class RawFilter : Stream
    {

        Stream responseStream;
        long position;
        StringBuilder responseHtml;

        /**//// <summary>
        /// 当原始数据采集成功后激发。
        /// </summary>
        public event EventHandler<RawDataEventArgs> OnRawDataRecordedEvent;

        public RawFilter(Stream inputStream)
        {
            responseStream = inputStream;
            responseHtml = new StringBuilder();
        }

//实现Stream 虚方法
        Filter Overrides#region Filter Overrides

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

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

        public override bool CanWrite
        {
            get
            {
                return true;
            }
        }
        public override void Close()
        {
            responseStream.Close();
        }

        public override void Flush()
        {
            responseStream.Flush();
        }

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

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

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

        public override long Seek(long offset, SeekOrigin origin)
        {
            return responseStream.Seek(offset, origin);
        }

        public override void SetLength(long length)
        {
            responseStream.SetLength(length);
        }
        #endregion

//关键的点，在HttpResponse 输入内容的时候，一定会调用此方法输入数据，所以要在此方法内截获数据
        public override void Write(byte[] buffer, int offset, int count)
        {
            string strBuffer = System.Text.UTF8Encoding.UTF8.GetString(buffer, offset, count);

//采用正则，检查输入的是否有页面结束符</html>
            Regex eof = new Regex("</html>", RegexOptions.IgnoreCase);

            if (!eof.IsMatch(strBuffer))
            {
              //页面没有输出完毕，继续追加内容
                responseHtml.Append(strBuffer);
            }
            else
            {
              //页面输出已经完毕，截获内容
                responseHtml.Append(strBuffer);
                string finalHtml = responseHtml.ToString();

            //激发数据已经获取事件
            OnRawDataRecordedEvent(this, new RawDataEventArgs(finalHtml));

                //继续传递要发出的内容写入流
                byte[] data = System.Text.UTF8Encoding.UTF8.GetBytes(finalHtml);

                responseStream.Write(data, 0, data.Length);
            }
        }
    }

using System;
using System.Web;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Diagnostics;

    public class HttpRawDataModule : IHttpModule
    {
        IHttpModule 成员#region IHttpModule 成员

        public void Dispose()
        {

        }

        public void Init(HttpApplication context)
        {
            //绑定事件，在对此请求处理过程全部结束后进行过滤操作
            context.ReleaseRequestState += new EventHandler(context_ReleaseRequestState);
        }

        #endregion

        /**//// <summary>
        /// 对此HTTP请求处理的过程全部结束
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void context_ReleaseRequestState(object sender, EventArgs e)
        {
            HttpApplication application = (HttpApplication)sender;

            //这里需要针对ASPX页面进行拦截，测试发现如果不这么做，Wap 访问站点图片容易显示为X，奇怪
            string[] temp = application.Request.CurrentExecutionFilePath.Split('.');
            if (temp.Length > 0 && temp[temp.Length - 1].ToLower() == "aspx")
            {
                //装配过滤器
                application.Response.Filter = new RawFilter(application.Response.Filter);

                //绑定过滤器事件
                RawFilter filter = (RawFilter)application.Response.Filter;
                filter.OnRawDataRecordedEvent += new EventHandler<RawDataEventArgs>(filter_OnRawDataRecordedEvent);
            }
        }

        /**//// <summary>
        /// 当原始数据采集到以后，入库 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void filter_OnRawDataRecordedEvent(object sender, RawDataEventArgs e)
        {
            string allcode = e.SourceCode;
            WapSite.SiteDataClass wapdata = new WapSite.SiteDataClass();
            wapdata.WriteRawDataLog(allcode);
        }
    }

  <system.web>
    <httpModules>
      <add name="RawDataModule" type="HttpRawDataModule"/>
    </httpModules>
  </system.web>