HttpHandler全站过滤替换Html输出

这几天，一直想找一个替换整站即将要输出到客户端Html方法，但是找了好多，都没有找到，找到最大级别的，也就是在页面中处理；再者，这两天又看到了dudu写的关于 outputcache bug 的文章，真让我感觉到，不理解原理看来真的不行的，没文化太可怕了，所以，必须要再次认真的审视下 HttpHandler 和 HttpModule 的作用及用法啦

一些基本的概念，这里就不说了，本来自己的博客就是为自己做备忘的，如果不行本文被你看到，有疑问的话，可以直接给我留言 :-)

先说 HttpHandler ，其实自定义 HttpHandler 也是蛮简单的，但是这个的作用不是太大，自定义HttpHandler也主要用在静态文件的处理上面了，比如说图片加水印、防盗链等等，都是对静态文件做的处理，因为 HttpHandler 和 asp.net 中的Page 只能 2 选1 操作，所以，用来做处理动态页面，是不太便利的。(asp.net 中的Page，即 System.Web.UI.Page ，也是一个 HttpHandler，只不过是经过扩展的、复杂的 HttpHandler)。

再说下 HttpModule 吧，感觉 HttpModule 能处理的事情比较多，也相对比较重要，另外使用比之前者也简单很多，因为有 Global.asax 文件嘛，你懂得，不需要往 WebConfig 配置啦。

HttpModule 中的事件比较多，在各个事件中，做一些处理还是很不错的，对于一些较深入的应用，前提搞HttpModule 是必须的

页面直接上代码吧，这写代码主要是完成以下两个任务：

1. 全局过滤站点的 HTML 输出

2. 页面加上 OutPutCache后， HttpModule 中的事件是否还执行

App_Code/MyModule.cs：

using System;
using System.Web;
using System.IO;
using System.Text;

/// <summary>
///MyModule 的摘要说明
/// </summary>
namespace ModuleDemo
{

    public class MyModule : IHttpModule
    {
        /*The Event
        BeginRequest     指示请求处理开始
        AuthenticateRequest     封装请求身份验证过程
        AuthorizeRequest     封装检查是否能利用以前缓存的输出页面处理请求的过程
        ResolveRequestCache     从缓存中得到相应时候触发
        AcquireRequestState     加载初始化Session时候触发
        PreRequestHandlerExecute     在Http请求进入HttpHandler之前触发
        PostRequestHandlerExecute     在Http请求进入HttpHandler之后触发
        ReleaseRequestState     存储Session状态时候触发
        UpdateRequestCache     更新缓存信息时触发
        EndRequest     在Http请求处理完成的时候触发
        PreSendRequestHenaders     在向客户端发送Header之前触发
        PreSendRequestConternt     在向客户端发送内容之前触发*/

        public void Init(HttpApplication app)
        {
            app.BeginRequest += new EventHandler(BeginRequest);
            app.AuthenticateRequest += new EventHandler(AuthenticateRequest);
            app.AuthorizeRequest += new EventHandler(AuthorizeRequest);
            app.ResolveRequestCache += new EventHandler(ResolveRequestCache);
            app.PreRequestHandlerExecute += new EventHandler(PreRequestHandlerExecute);
            app.PostRequestHandlerExecute += new EventHandler(PostRequestHandlerExecute);
            app.ReleaseRequestState += new EventHandler(ReleaseRequestState);
            app.UpdateRequestCache += new EventHandler(UpdateRequestCache);
            app.EndRequest += new EventHandler(EndRequest);
            app.PreSendRequestHeaders += new EventHandler(PreSendRequestHenaders);
            app.PreSendRequestContent += new EventHandler(PreSendRequestConternt);
        }

        private void BeginRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>BeginRequet！" + DateTime.Now.Millisecond.ToString() + "<br />");
            app.Response.Filter = new ReplaceHtml(app.Response.Filter);
        }

        private void AuthenticateRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>AuthenticateRequest！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void AuthorizeRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>AuthorizeRequest！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void ResolveRequestCache(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>ResolveRequestCache！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void AcquireRequestState(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>AcquireRequestState！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void PreRequestHandlerExecute(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>PreRequestHandlerExecute！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void PostRequestHandlerExecute(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>PostRequestHandlerExecute！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void ReleaseRequestState(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>ReleaseRequestState！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void UpdateRequestCache(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>UpdateRequestCache！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void EndRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>EndRequest！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void PreSendRequestHenaders(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>PreSendRequestHenaders！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        private void PreSendRequestConternt(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            app.Response.Write("<span style='color:gray;'>Module : </span>PreSendRequestConternt！" + DateTime.Now.Millisecond.ToString() + "<br />");
        }

        public void Dispose() { }
    }

    public class ReplaceHtml : Stream
    {
        private Stream m_sink;
        private long m_position;

        public ReplaceHtml(Stream sink)
        {
            m_sink = sink;
        }

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

        // Override the Write method to filter Response to a file.
        public override void Write(byte[] buffer, int offset, int count)
        {
            string html = Encoding.UTF8.GetString(buffer);
            html = html.Replace("Replace", "REPLACE");
            byte[] b = Encoding.UTF8.GetBytes(html);
            m_sink.Write(b, 0, b.Length);
        }

        // The following members of Stream must be overriden.
        public override bool CanRead
        {
            get { return true; }
        }

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

        public override bool CanWrite
        {
            get { return false; }
        }

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

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

        public override long Seek(long offset, System.IO.SeekOrigin direction)
        {
            return 0;
        }

        public override void SetLength(long length)
        {
            m_sink.SetLength(length);
        }

        public override void Close()
        {
            m_sink.Close();
        }

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

    }

}

default.aspx

<%@ Page Language="C#"%>

<%@ OutputCache VaryByParam="*" Duration="5" %>

protected void Page_Load(object sender, EventArgs e)

{

Response.Write("Page Load At：o"+ DateTime.Now.Millisecond.ToString());

label1.Text = "I'm a label！?";

}

protected override void Render(HtmlTextWriter writer)

{

System.IO.StringWriter sw = new System.IO.StringWriter();

HtmlTextWriter htmlWriter = new HtmlTextWriter(sw);

base.Render(htmlWriter);

string html = sw.ToString();

//html = html.Replace("HTML","H TML");

html = "<br />----Begin Render" + html + "----End Render<br />";

writer.Write(html);

}

</script>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<h1 style="color:gray;">测a试? Replace</h1>

</body>

</html>

Web.Config 配置：

</httpModules>

关键词： HttpHandler全站过滤Html输出，过滤页面Html代码，全站html过滤