Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim rd As New Random
Dim RdNum As Integer = rd.Next(1000, 9999)
Session("checkcode") = RdNum
Dim newbitmap As New Bitmap(36, 16, Imaging.PixelFormat.Format32bppArgb)
Dim g As Graphics = Graphics.FromImage(newbitmap)
Dim rectangle As New RectangleF(0, 0, 36, 16)
g.FillRectangle(New SolidBrush(Color.BurlyWood), rectangle)
Dim txtfont As New Font("宋体", 10)
g.DrawString(RdNum.ToString, txtfont, New SolidBrush(Color.Blue), rectangle)
newbitmap.Save(Server.MapPath("") & "\test.gif")
End Sub Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If CStr(TextBox1.Text) = "" Then
Response.Write("<script>alert('请输入验证码!')</script>")
Else
If CStr(TextBox1.Text) <> Session("checkcode") Then
Response.Write("<script>alert('验证码错误!')</script>")
Else
Response.Write("<script>alert('验证码验证成功!')</script>")
End If
End If
End Sub
End Class
Dim rd As New Random
Dim RdNum As Integer = rd.Next(1000, 9999)
Session("checkcode") = RdNum
Dim newbitmap As New Bitmap(36, 16, Imaging.PixelFormat.Format32bppArgb)
Dim g As Graphics = Graphics.FromImage(newbitmap)
Dim rectangle As New RectangleF(0, 0, 36, 16)
g.FillRectangle(New SolidBrush(Color.BurlyWood), rectangle)
Dim txtfont As New Font("宋体", 10)
g.DrawString(RdNum.ToString, txtfont, New SolidBrush(Color.Blue), rectangle)
newbitmap.Save(Server.MapPath("") & "\test.gif")
End Sub Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If CStr(TextBox1.Text) = "" Then
Response.Write("<script>alert('请输入验证码!')</script>")
Else
If CStr(TextBox1.Text) <> Session("checkcode") Then
Response.Write("<script>alert('验证码错误!')</script>")
Else
Response.Write("<script>alert('验证码验证成功!')</script>")
End If
End If
End Sub
End Class
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if(!IsPostBack)
要不回发不刷新
Session("checkcode")应该是一个对像吧,加一个ToString()试试看,对的C#代码如下,可参考一下,VB.net不熟悉
if(TextBox1.Text.Trim()==Session["checkcode"].ToString().Trim())
{
//登录成功
}
else
{
//登录失败
}还有你的javasctipt输出,尽量不要直接用response.write(
最好采用page.ClientScript.RegisterClientScriptBlock
或者
page.ClientScript.RegisterStartupScript
来做
你可以调式就会发现 当提交的时候 又重新执行load里的事件 那样就又生成了一个验证码 这样就不会成功了