合法性校验有很多方法，要视情况而定，比如说可以用正则表达式，如果是数字，除了正则表达式，也可以用诸如TryParse这种方法。
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Dim CtrlRange As Object
On Error Resume Next
Do
Err.Clear()
CtrlRange = Ie.Document.Body.DomElement.createControlRange()
CtrlRange.Add(Ie.Document.DomDocument.GetElementById("verifypic"))
CtrlRange.execCommand("Copy") '获取验证码
If Clipboard.ContainsData(DataFormats.Bitmap) Then
PictureBox1.Image = Clipboard.GetData(DataFormats.Bitmap) '在Picture1控件上显示
End If
If Err.Number 0 Then WaitingMS(100) ‘延时
Loop While Err.Number 0
以前找的 vbnet里也可以用
Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus
if IsNumeric(TextBox1.Text()) = False Then
MsgBox("内容不是数字")
End If
End Sub
建一个YanzhenCard.aspx文件
保留%@ Page Language="VB" AutoEventWireup="false" CodeFile="YanzhenCard.aspx.vb" Inherits="YanzhenCard" %,其余删除
如下是代码:
Imports System.IO
Imports System.Drawing
Partial Class YanzhenCard
Inherits System.Web.UI.Page
Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
Dim VNum As String = GenerateRandom(4)
Session("VNum") = VNum
ValidateCode(VNum)
End If
End Sub
Private Sub ValidateCode(ByVal VNum As String)
Dim Gheight As Integer = CType((VNum.Length * 15), Integer)
Dim Img As Bitmap = New Bitmap(Gheight, 20) 'Bitmap是用于处理由像素数据定义的图像
Dim g As Graphics = Graphics.FromImage(Img) 'Graphics.FromImage 从指定的Image创建新的Graphics
g.DrawString(VNum, New Font("Arial", 12), New SolidBrush(Color.Red), 5, 0) 'g.DrawString()在指定位置并且用指定的Brush和Font对象绘制指定的文本字符串。
Dim ms As MemoryStream = New MemoryStream '创建其支持存储区为内存的流。
Img.Save(ms, System.Drawing.Imaging.ImageFormat.Png)
Response.ClearContent()
Response.ContentType = "image/PNG"
Response.BinaryWrite(ms.ToArray)
Response.Write(VNum)
g.Dispose()
Img.Dispose()
Response.End()
End Sub
Private Shared constant As Char() = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"}
Public Shared Function GenerateRandom(ByVal Length As Integer) As String
Dim newRandom As System.Text.StringBuilder = New System.Text.StringBuilder(26)
Dim rd As Random = New Random
Dim i As Integer = 0
While i Length
newRandom.Append(constant(rd.Next(26)))
System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)
End While
Return newRandom.ToString
End Function
End Class
调用方法:asp:ImageButton ID="Yanzhengma_Card" runat="server" ImageUrl="YanzhenCard.aspx" Height="20px" Width="75px" BorderColor="#6699cc" BorderStyle="Solid" BorderWidth="1px" /
textbox的text属性是string类型的，当你未输入任何数据，或者输入数据无法转换为integer型时就会有这个错误，在验证前先判断下类型
将用户名，密码，用户类型存在数据库中，登陆时比较输入的值是否与数据库相同即可。
