Login.OnLoggingIn(LoginCancelEventArgs) 方法

参考

定义

命名空间:: System.Web.UI.WebControls

程序集:: System.Web.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

在用户提交登录信息但进行身份验证前引发 LoggingIn 事件。

protected:
 virtual void OnLoggingIn(System::Web::UI::WebControls::LoginCancelEventArgs ^ e);

protected virtual void OnLoggingIn (System.Web.UI.WebControls.LoginCancelEventArgs e);

abstract member OnLoggingIn : System.Web.UI.WebControls.LoginCancelEventArgs -> unit
override this.OnLoggingIn : System.Web.UI.WebControls.LoginCancelEventArgs -> unit

Protected Overridable Sub OnLoggingIn (e As LoginCancelEventArgs)

参数

e: LoginCancelEventArgs

包含事件数据的 LoginCancelEventArgs。

示例

下面的代码示例使用 LoggingIn 事件来确保用户在属性中 UserName 输入了格式正确的电子邮件地址。否则， LoggingIn 事件处理程序将取消登录尝试，并显示属性中指定的 InstructionText 错误消息。

<%@ page language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
// This custom Login control checks the user name 
// entered by the user is a valid email address
class CustomLogin : Login
{
    bool IsValidEmail(string strIn)
    {
        // Return true if strIn is in valid email format.
        return Regex.IsMatch(strIn, @"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$"); 
    }

    override protected void OnLoggingIn(System.Web.UI.WebControls.LoginCancelEventArgs e)
    {
        if (!IsValidEmail(UserName)) 
        {
            InstructionText = "You must enter a valid email address.";
            e.Cancel = true;
        }
        else 
        {
            InstructionText = String.Empty;
        }
    }
}

    // Add the custom login control to the page.
    void Page_Load(object sender, EventArgs e) 
    {
        CustomLogin loginControl = new CustomLogin();
        loginControl.ID = "loginControl";
        Placeholder1.Controls.Add(loginControl);
    }

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
        <form id="Form1" runat="server">
            <asp:placeholder id="Placeholder1" runat="server"></asp:placeholder>
        </form>
    </body>
</html>

<%@ page language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    ' This custom Login control checks the user name
    ' entered by the user is a valid email address.
    Class CustomLogin
        Inherits Login
        
        Function IsValidEmail(ByVal strIn As String) As Boolean
            ' Return true if strIn is in valid email format.
            Return Regex.IsMatch(strIn, ("^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$"))
        End Function

        Overrides Protected Sub OnLoggingIn(ByVal e As System.Web.UI.WebControls.LoginCancelEventArgs)
            If Not IsValidEmail(UserName) Then
                InstructionText = "You must enter a valid email address."
                e.Cancel = True
            Else
                InstructionText = String.Empty
            End If
        End Sub
    End Class
    
    ' Add the custom login control to the page.
    Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        Dim loginControl As New CustomLogin

        loginControl.ID = "loginControl"

        PlaceHolder1.Controls.Add(loginControl)
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
<form id="Form1" runat="server">
    <asp:placeholder id="Placeholder1" runat="Server"></asp:placeholder>
</form>
</body>
</html>

下面的代码示例演示如何扩展 Login 控件。控件 CustomLogin 包含一个 DropDownList 控件，该控件允许用户选择向其进行身份验证的成员资格提供程序。 (这些提供程序在 Web.config.) 在 OnLoggingIn 方法中 MembershipProvider ，属性设置为控件的 DropDownList 选定值。

重要

此示例包含一个接受用户输入的文本框，这是一个潜在的安全威胁。默认情况下，ASP.NET 网页验证用户输入是否不包含脚本或 HTML 元素。有关详细信息，请参阅脚本侵入概述。

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace Samples.AspNet.Controls
{
    public sealed class CustomLogin : Login
    {
        public CustomLogin() { }
        
        protected override void OnLoggingIn(LoginCancelEventArgs e)
        {
            // Set the Membership provider for the Login control from a DropDownList.
            DropDownList list = (DropDownList)this.FindControl("domain");
            this.MembershipProvider = list.SelectedValue;
            base.OnLoggingIn(e);
        }
        
        protected override void CreateChildControls()
        {
            LayoutTemplate = new MyTemplate();
            base.CreateChildControls();
        }
    }
    
    // A Template that contains the child controls.
    public class MyTemplate : ITemplate
    {
        void ITemplate.InstantiateIn(Control container)
        {
            // A TextBox for the user name.
            TextBox username = new TextBox();
            username.ID = "username";
            
            // A TextBox for the password.
            TextBox password = new TextBox();
            password.ID = "password";
            
            // A CheckBox to remember the user on subsequent visits.
            CheckBox remember = new CheckBox();
            remember.ID = "RememberMe";
            remember.Text = "Don't forget me!";
            
            // Failure Text.
            Literal failure = new Literal();
            failure.ID = "FailureText";
            
            // A DropDownList to choose the Membership provider.
            DropDownList domain = new DropDownList();
            domain.ID = "Domain";
            domain.Items.Add(new ListItem("SqlMembers"));
            domain.Items.Add(new ListItem("SqlMembers2"));
            
            // A Button to log in.
            Button submit = new Button();
            submit.CommandName = "login";
            submit.Text = "LOGIN";

            container.Controls.Add(new LiteralControl("UserName:"));
            container.Controls.Add(username);
            container.Controls.Add(new LiteralControl("<br>Password:"));
            container.Controls.Add(password);
            container.Controls.Add(new LiteralControl("<br>"));
            container.Controls.Add(remember);
            container.Controls.Add(new LiteralControl("<br>Domain:"));
            container.Controls.Add(domain);
            container.Controls.Add(new LiteralControl("<br>"));
            container.Controls.Add(failure);
            container.Controls.Add(new LiteralControl("<br>"));
            container.Controls.Add(submit);
        }
    }    
}

Imports System.Data
Imports System.Configuration
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls

Namespace Samples.AspNet.Controls

    NotInheritable Public Class CustomLogin
        Inherits Login

        Public Sub New() 
        End Sub

        Protected Overrides Sub OnLoggingIn(ByVal e As LoginCancelEventArgs) 

            ' Set the Membership provider for the Login control from a DropDownList.
            Dim list As DropDownList = CType(Me.FindControl("domain"), DropDownList)
            Me.MembershipProvider = list.SelectedValue
            MyBase.OnLoggingIn(e)

        End Sub


        Protected Overrides Sub CreateChildControls() 

            LayoutTemplate = New MyTemplate()
            MyBase.CreateChildControls()

        End Sub
    End Class

    ' A Template that contains the child controls.
    Public Class MyTemplate
        Implements ITemplate

        Sub InstantiateIn(ByVal container As Control)  Implements ITemplate.InstantiateIn
            ' A TextBox for the user name.
            Dim username As New TextBox()
            username.ID = "username"

            ' A TextBox for the password.
            Dim password As New TextBox()
            password.ID = "password"

            ' A CheckBox to remember the user on subsequent visits.
            Dim remember As New CheckBox()
            remember.ID = "RememberMe"
            remember.Text = "Don't forget me!"

            ' Failure Text.
            Dim failure As New Literal()
            failure.ID = "FailureText"

            ' A DropDownList to choose the Membership provider.
            Dim domain As New DropDownList()
            domain.ID = "Domain"
            domain.Items.Add(New ListItem("SqlMembers"))
            domain.Items.Add(New ListItem("SqlMembers2"))

            ' A Button to log in.
            Dim submit As New Button()
            submit.CommandName = "login"
            submit.Text = "LOGIN"

            container.Controls.Add(New LiteralControl("UserName:"))
            container.Controls.Add(username)
            container.Controls.Add(New LiteralControl("<br>Password:"))
            container.Controls.Add(password)
            container.Controls.Add(New LiteralControl("<br>"))
            container.Controls.Add(remember)
            container.Controls.Add(New LiteralControl("<br>Domain:"))
            container.Controls.Add(domain)
            container.Controls.Add(New LiteralControl("<br>"))
            container.Controls.Add(failure)
            container.Controls.Add(New LiteralControl("<br>"))
            container.Controls.Add(submit)

        End Sub
    End Class
End Namespace

注解

OnLoggingIn 方法引发 LoggingIn 事件。 LoggingIn使用事件执行在对用户进行身份验证之前所需的任何处理，或执行自定义验证。

引发事件时，将通过委托调用事件处理程序。有关详细信息，请参阅处理和引发事件。

OnLoggingIn 方法还允许派生类对事件进行处理而不必附加委托。这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnLoggingIn(LoginCancelEventArgs) 时，一定要调用基类的 OnLoggingIn(LoginCancelEventArgs) 方法，以便已注册的委托对事件进行接收。

适用于

另请参阅

ASP.NET 登录控件概述

通过

Login.OnLoggingIn(LoginCancelEventArgs) 方法

定义

参数

示例

注解

继承者说明

适用于

另请参阅

其他资源