httpModule测试

 

本来标题应该加上输出过滤的，想想还是不加好了，看了老赵的关于整站关键字过滤的文章，感觉还晕乎，以前也没怎么用过httpModule这东西，在网上看了下相关的文章，讲的还是比较多的，看到一篇关于输出过滤的文章，原文地址是http://www.cnblogs.com/zgqys1980/archive/2008/09/02/1281895.html 基本还算能看明白，呵呵，我这个算是转载吧。

     原文的输出过滤主要是通过ReleaseRequestState这个事件来处理的，即执行完所有请求事件处理后发生，也就是请求处理全部结束后再进行过滤，这么一来截获的是整个page的html源文件了，然后对源文件内容进行特殊字符替换过滤处理（当然在替换前可以将原内容进行相关写入操作保存起来），捕获完成是以"</html>"为标志，因为最终在浏览器中呈现的html文件内容都是以"</html>"结尾的。把输出过滤的处理类贴下面(保留原作者注释同时也加了几句注释，另外注释掉的部分代码是将替换前的原替换前的html内容保存处理)

 using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Reflection;
using System.Text.RegularExpressions;
using System.IO;
namespace httpModuleOutputFilter
{

    public class OutputFilter : IHttpModule
    {
        private HttpApplication _contextApplication;
        public void Init(HttpApplication context)
        {
            _contextApplication = 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);

        }
        public void Dispose()
        {
            _contextApplication = null;
            _contextApplication.Dispose();
        }

        /**/
        /// <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
            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;//allcode就是截获的替换前的整个page页面的html
            //WapSite.SiteDataClass wapdata = new WapSite.SiteDataClass();
            //wapdata.WriteRawDataLog(allcode);
        }

    }

     /**//// <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

        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);
        }

        //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));//finalHtml就是源文件内容

                //继续传递要发出的内容写入流
                byte[] data = System.Text.UTF8Encoding.UTF8.GetBytes(finalHtml.Replace("城管","**"));//测试 捕获的源文件内特殊字符容替换后输出

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

 

    上面就是一个httpModule的简单应用了，至于这个方案的其它方面我就不说了，也不好说，主要是大家能看得明白这个简单的httpModule应用就好，另外在web项目的里添加编译好的httpModule.dll引用，还有config里加一句<httpModules>
        <add name="OutputFilter" type="httpModuleOutputFilter.OutputFilter, httpModule" />
      </httpModules>