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HttpUtility Class

Provides methods for encoding and decoding URLs when processing Web requests. This class cannot be inherited.

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

Public NotInheritable Class HttpUtility
Dim instance As HttpUtility

public final class HttpUtility
public final class HttpUtility

The HttpUtility class is used internally by the HttpServerUtility class, whose methods and properties are exposed through the intrinsic ASP.NET Server object. Additionally, the HttpUtility class contains encoding and decoding utility methods that are not accessible from the Server.

The following code example demonstrates the use of the HtmlEncode, HtmlDecode, and ParseQueryString methods of the HttpUtility class.

<%@ Page Language="VB" %>

<script runat="server">

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

    Dim currurl As String = HttpContext.Current.Request.RawUrl
    Dim querystring As String = Nothing
    ' Check to make sure some query string variables
    ' exist and if not add some and redirect.
    Dim iqs As Int32 = currurl.IndexOf("?".ToCharArray())
    If (iqs = -1) Then
      Dim redirecturl As String = currurl & "?var1=1&var2=2+2%2f3&var1=3"
      Response.Redirect(redirecturl, True)
      ' If query string variables exist, put them in
      ' a string.
    ElseIf (iqs >= 0) Then
      If (iqs < currurl.Length - 1) Then
        querystring = currurl.Substring(iqs + 1)
      End If
    End If

    ' Parse the query string variables into a NameValueCollection.
    Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
    ' Iterate through the collection.
    Dim sb As New StringBuilder()
    For Each s As String In qscoll.AllKeys
      sb.Append(s & " - " & qscoll(s) & "<br>")
    Next s
    ' Write the results to the appropriate labels.
    ParseOutput.Text = sb.ToString()
    UrlRawOutput.Text = currurl
    UrlEncodedOutput.Text = HttpUtility.UrlEncode(currurl)
    UrlDecodedOutput.Text = HttpUtility.UrlDecode(currurl)
  End Sub

<head id="Head1" runat="server">
    <title>HttpUtility ParseQueryString Example</title>
    <form id="Form1" runat="server">
      The raw url is: <br />
      <asp:Label  id="UrlRawOutput"
                  runat="server" />
      <br /><br />
      The url encoded is: <br />
      <asp:Label  id="UrlEncodedOutput"
                  runat="server" />
      <br /><br />
      The url decoded is: <br />
      <asp:Label  id="UrlDecodedOutput"
                  runat="server" />
      <br /><br />
      The query string NameValueCollection is: <br />
      <asp:Label  id="ParseOutput"
                  runat="server" />

  • AspNetHostingPermission  for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0