HttpResponse.Filter Property (System.Web)

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Filter Property

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This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

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)

Syntax

Visual Basic (Declaration)

Public Property Filter As Stream

Visual Basic (Usage)

Dim instance As HttpResponse
Dim value As Stream

value = instance.Filter

instance.Filter = value

public Stream Filter { get; set; }

Visual C++

public:
property Stream^ Filter {
    Stream^ get ();
    void set (Stream^ value);
}

JScript

public function get Filter () : Stream
public function set Filter (value : Stream)

Property Value

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

Exceptions

Exception	Condition
HttpException	Filtering is not allowed with the entity.

Remarks

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.

Examples

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.

Visual Basic

<%@ Page Language="VB" Debug="true"%>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="Samples.AspNet.VB.Controls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

    ' 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.
    Dim fullpath As String = Request.MapPath("~\\TestFile.txt")

    Try

      Dim sr As StreamReader = New StreamReader(fullpath)

      Do While sr.Peek() >= 0
        Response.Write(Convert.ToChar(sr.Read()))
      Loop
      sr.Close()
      Message.Text = "Reading the file was successful."

    Catch ex As Exception

      Message.Text = "The process failed."

    End Try


  End Sub

</script>
<html  >
  <head>
    <title>HttpResponse.MapPath Example</title>
  </head>
  <body>
    <form id="Form1" runat="server">

      <asp:Label id="Message" 
                 runat="server"/>

    </form>
  </body>
</html>

<%@ Page Language="C#" %>
<%@ Import Namespace="System.IO" %>
<%@ import Namespace="Samples.AspNet.CS.Controls"  %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<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");

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

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

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

      <asp:Label id="Message" 
                 runat="server"/>

    </form>
  </body>
</html>

Platforms

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.

Version Information

.NET Framework

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

Reference

HttpResponse Class

HttpResponse Members

System.Web Namespace