本文實例主要實現(xiàn)對已經生成了HTML的頁面做一些輸出到客戶端之前的處理。

方法的實現(xiàn)原理是：把Response的輸出重定向到自定義的容器內，也就是我們的StringBuilder對象里，在HTML所有的向頁面輸出都變成了向StringBuilder輸出，然后我們對StringBuilder處理完成之后，再把Response的輸出重定向到原來的頁面上，然后再通過Response.Write方法把StringBuilder的內容輸出到頁面上。

這里之所以用反射，是因為Response對象的OutPut屬性是只讀的，通過反編譯該類的程序集發(fā)現(xiàn)，OutPut實際上是內部私有成員 _writer來實現(xiàn)輸出的。因此通過反射來改寫該成員的值以實現(xiàn)輸出流的重定向。

具體功能代碼如下：

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Text; using System.IO; using System.Reflection; public partial class _Default : System.Web.UI.Page  {   StringBuilder content = new StringBuilder();   TextWriter tw_old, tw_new;   FieldInfo tw_field;   protected void Page_Load(object sender, EventArgs e)   {     var context = HttpContext.Current;      tw_old = context.Response.Output;//Response原來的OutPut     tw_new = new StringWriter(content);//一個StringWriter,用來獲取頁面內容     var type_rp = context.Response.GetType();     //通過反射獲取對象的私有字段     tw_field = type_rp.GetField("_writer", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);     tw_field.SetValue(context.Response, tw_new);   }   protected override void Render(HtmlTextWriter writer)   {     base.Render(writer);     //替換回Response的OutPut     tw_field.SetValue(HttpContext.Current.Response, tw_old);     //做自己的處理     content.AppendLine("<!--江湖小子-->");     HttpContext.Current.Response.Write(content.ToString());   } }  

方法二，用HttpModul來實現(xiàn)：  

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.IO; using System.Text; using System.Reflection; /// <summary> ///HttpModule 的摘要說明 /// </summary> public class HttpModule : IHttpModule {   private HttpApplication _contextApplication;   private TextWriter tw_new, tw_old;   private StringBuilder _content;   private FieldInfo tw_field;   public void Init(HttpApplication context)   {     _contextApplication = context;     _contextApplication.PreRequestHandlerExecute += new EventHandler(_contextApplication_PreRequestHandlerExecute);   }   public void Dispose()   {     _contextApplication = null;     _contextApplication.Dispose();   }   public void _contextApplication_PreRequestHandlerExecute(object sender, EventArgs e)   {     HttpContext context = _contextApplication.Context;      var _page = context.Handler as System.Web.UI.Page;     _page.Unload += new EventHandler(_page_Unload);      _content = new StringBuilder();     tw_old = context.Response.Output;//Response原來的OutPut     tw_new = new StringWriter(_content);//一個StringWriter,用來獲取頁面內容     var type_rp = context.Response.GetType();     tw_field = type_rp.GetField("_writer", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);     tw_field.SetValue(context.Response, tw_new);   }   void _page_Unload(object sender, EventArgs e)   {     //替換回Response的OutPut     tw_field.SetValue(HttpContext.Current.Response, tw_old);     //做自己的處理     _content.AppendLine("<!--江湖小子-->");     HttpContext.Current.Response.Write(_content.ToString());   } }  

方法三：

public class HttpModule : IHttpModule {   private HttpApplication _contextApplication;   private TextWriter tw_new, tw_old;   private StringBuilder _content;   private FieldInfo tw_field;   public void Init(HttpApplication application)   {     _contextApplication = application;     _contextApplication.BeginRequest += new EventHandler(_contextApplication_BeginRequest);     _contextApplication.EndRequest +=new EventHandler(_contextApplication_EndRequest);   }   void _contextApplication_BeginRequest(object sender, EventArgs e)   {     _content = new StringBuilder();     tw_old = _contextApplication.Response.Output;     tw_new = new StringWriter(_content);     var type_rp = _contextApplication.Response.GetType();     tw_field = type_rp.GetField("_writer", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);     tw_field.SetValue(_contextApplication.Response, tw_new);   }   void _contextApplication_EndRequest(object sender, EventArgs e)   {     tw_field.SetValue(_contextApplication.Response, tw_old);     //做自己的處理     _content.AppendLine("<!--jhxz-->");     _contextApplication.Response.Write(_content.ToString());   }   public void Dispose()   {     _contextApplication = null;     _contextApplication.Dispose();   } }

相信本文所述對大家的ASP.NET程序設計有一定的借鑒價值。

AspNet技術：攔截asp.net輸出流并進行處理的方法，轉載需保留來源！

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