HtmlInputFile.OnPreRender(EventArgs) Methode
Definitie
Belangrijk
Bepaalde informatie heeft betrekking op een voorlopige productversie die aanzienlijk kan worden gewijzigd voordat deze wordt uitgebracht. Microsoft biedt geen enkele expliciete of impliciete garanties met betrekking tot de informatie die hier wordt verstrekt.
Hiermee wordt de PreRender gebeurtenis voor het HtmlInputFile besturingselement gegenereerd.
protected:
override void OnPreRender(EventArgs ^ e);protected public:
override void OnPreRender(EventArgs ^ e);protected override void OnPreRender(EventArgs e);protected internal override void OnPreRender(EventArgs e);override this.OnPreRender : EventArgs -> unitProtected Overrides Sub OnPreRender (e As EventArgs)Protected Friend Overrides Sub OnPreRender (e As EventArgs)Parameters
Voorbeelden
In het volgende codevoorbeeld ziet u hoe u de OnPreRender methode overschrijft, zodat een Title kenmerk altijd wordt toegevoegd aan elk aangepast besturingselement HtmlInputFile . Voor dit voorbeeld werkt het goed als u een map maakt die wordt aangeroepen Temp op station C van uw computer.
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Button1_Click(object Source, EventArgs e)
{
// Make sure a file was submitted.
if (HtmlInputText1.Value == "")
{
Span1.InnerHtml = "Error: You must enter a file name.";
}
// Save the file.
else if (HtmlInputFile1.PostedFile != null)
{
try
{
HtmlInputFile1.PostedFile.SaveAs("c:\\temp\\" + HtmlInputText1.Value);
Span1.InnerHtml = "File uploaded successfully to: <b>c:\\temp\\" +
HtmlInputText1.Value + "</b> on the Web server.";
}
catch (Exception exc)
{
Span1.InnerHtml = "Error saving <b>c:\\temp\\" +
HtmlInputText1.Value + "</b><br />" + exc.ToString() + ".";
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Custom HtmlInputFile OnPreRender Example</title>
</head>
<body>
<form id="form1" enctype="multipart/form-data"
runat="server">
<h3>Custom HtmlInputFile OnPreRender Example</h3>
Select File to Upload:
<aspSample:CustomHtmlInputFileOnPreRender
id="HtmlInputFile1"
type="file"
runat="server"
name="HtmlInputFile1">
<p>
Save as file name (no path):
<input id="HtmlInputText1"
type="text"
runat="server"
name="Text1" />
</p>
<p>
<span id="Span1"
style="font: 8pt verdana;"
runat="server" />
</p>
<p>
<input type="button"
id="Button1"
value="Upload"
onserverclick="Button1_Click"
runat="server"
name="Button1" />
</p>
</form>
</body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Button1_Click(ByVal source As Object, ByVal e As EventArgs)
' Make sure the file was submitted.
If HtmlInputText1.Value = "" Then
Span1.InnerHtml = "Error: You must enter a file name."
' Save the file
ElseIf Not (HtmlInputFile1.PostedFile Is Nothing) Then
Try
HtmlInputFile1.PostedFile.SaveAs("c:\\temp\\" & HtmlInputText1.Value)
Span1.InnerHtml = "File uploaded successfully to: <b>c:\temp\" _
& HtmlInputText1.Value & "</b> on the Web server."
Catch exc As Exception
Span1.InnerHtml = "Error saving <b>c:\temp\" _
& HtmlInputText1.Value & "</b><br />" _
& exc.ToString() & "."
End Try
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Custom HtmlInputFile OnPreRender Example</title>
</head>
<body>
<form id="form1" enctype="multipart/form-data"
runat="server">
<h3>Custom HtmlInputFile OnPreRender Example</h3>
Select File to Upload:
<aspSample:CustomHtmlInputFileOnPreRender
id="HtmlInputFile1"
type="file"
runat="server"
name="HtmlInputFile1">
<p>
Save as file name (no path):
<input id="HtmlInputText1"
type="text"
runat="server"
name="Text1" />
</p>
<p>
<span id="Span1"
style="font: 8pt verdana;"
runat="server" />
</p>
<p>
<input type="button"
id="Button1"
value="Upload"
onserverclick="Button1_Click"
runat="server"
name="Button1" />
</p>
</form>
</body>
</html>
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomHtmlInputFileOnPreRender : System.Web.UI.HtmlControls.HtmlInputFile
{
protected override void OnPreRender(System.EventArgs e)
{
// Call the base OnPreRender method.
base.OnPreRender(e);
// Add a Title attribute to the HtmlInputFile control.
this.Attributes.Add("title", "Click the Browse button to select a file to upload.");
}
}
}
Imports System.Web
Imports System.Security.Permissions
Namespace Samples.AspNet.VB.Controls
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlInputFileOnPreRender
Inherits System.Web.UI.HtmlControls.HtmlInputFile
Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
' Call the base OnPreRender method.
MyBase.OnPreRender(e)
' Add a Title attribute to the HtmlInputFile control.
Me.Attributes.Add("title", "Click the Browse button to select a file to upload.")
End Sub
End Class
End Namespace
Opmerkingen
Als er geen codering is opgegeven voor het besturingselement van HtmlForm de webpagina, wordt de Enctype eigenschap ingesteld op 'multipart/form-data'.
