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HttpResponse.Filter Property

Gets or sets a wrapping filter object that is used to modify the HTTP entity body before transmission.

Namespace:  System.Web
Assembly:  System.Web (in System.Web.dll)

public Stream Filter { get; set; }

Property Value

Type: System.IO.Stream
The Stream object that acts as the output filter.


Filtering is not allowed with the entity.

When you create a Stream object and set the Filter property to the Stream object, all HTTP output sent by Write passes through the filter.

The following example is an ASP.NET page that sets the Filter property to a new instance of the UpperCaseFilter class, a custom Stream class that converts all text that passes through it to uppercase. The information about the request is saved to a text file, and then the Filter property is set. After the response filter is in place, the code calls the MapPath method to get the absolute path to a text file named TestFile.txt that serves as the source for the content of the response. The code then creates a new StreamReader object to read the text file from beginning to end, and then calls the Write method to display the content of the file on the page.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.IO" %>
<%@ import Namespace="Samples.AspNet.CS.Controls"  %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
<script runat="server">

    private void Page_Load(object sender, EventArgs e)

      // Filter the text to be rendered as all uppercase.
      Response.Filter = new UpperCaseFilterStream(Response.Filter);

      // Convert a virtual path to a fully qualified physical path.
      string fullpath = Request.MapPath("~\\TestFile.txt");

        // Read the contents of the file using a StreamReader. 
        using (StreamReader sr = new StreamReader(fullpath))
        while (sr.Peek() >= 0)
        Message.Text = "Reading the file was successful.";

      catch (Exception ex)
        Message.Text = "The process failed.";

<html xmlns="" >
    <title>HttpResponse.MapPath Example</title>
    <form id="form1" runat="server">

      <asp:Label id="Message" 


Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0