Asp.Net生成图片验证码(vb)

Validate.vb
代码如下

Imports  System
Imports  System.Drawing.Drawing2D
Imports  System.Drawing.imaging
Imports  System.Drawing
Imports  System.Web.UI
Imports  System.IO
Public   Class Validate Class Validate

    Public Class CreatValidateNumberClass CreatValidateNumber
        '生成验证码
        Public Function CreatValidateNumber()Function CreatValidateNumber(ByVal length As Integer)
            Dim vchar As String = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,w,x,y,z"
            Dim vcarray() As String = Split(vchar, ",") '将字符串生成数组 
            Dim vnum As String = ""
            Dim i As Byte
            For i = 1 To length
                Randomize()
                vnum = vnum & vcarray(Int(35 * Rnd())) '数组一般从0开始读取，所以这里为35*rnd 
            Next
            Return vnum
        End Function
        '创建验证码图片
        Public Sub CreatevalidateGraphic()Sub CreatevalidateGraphic(ByVal page As Page, ByVal validatenum As String)
            Dim image As Bitmap = New Bitmap(CInt(Math.Ceiling(validatenum.Length * 12.5)), 22)
            Dim g As Graphics = Graphics.FromImage(image)
            Try
                '生成随机生成器
                Dim random As New Random
                '清空图片背景色
                g.Clear(Color.White)
                '画图片的干扰线
                Dim i As Integer
                For i = 0 To 24
                    Dim x1 As Integer = random.Next(image.Width)
                    Dim x2 As Integer = random.Next(image.Width)
                    Dim y1 As Integer = random.Next(image.Height)
                    Dim y2 As Integer = random.Next(image.Height)
                    g.DrawLine(New Pen(Color.Silver), x1, y1, x2, y2)
                Next
                '画验证码
                Dim font As Font = New Font("Arial", 12, (FontStyle.Bold And FontStyle.Italic))
                Dim brush As LinearGradientBrush = New LinearGradientBrush(New Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, True)
                g.DrawString(validatenum, font, brush, 3, 2)
                '画前景干扰点
                For i = 0 To 24
                    Dim x As Integer = random.Next(image.Width)
                    Dim y As Integer = random.Next(image.Height)
                    image.SetPixel(x, y, Color.FromArgb(random.Next()))
                Next
                '画图片的边框线
                g.DrawRectangle(New Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1)
                '保存图片
                Dim stream As New MemoryStream
                image.Save(stream, ImageFormat.Jpeg)
                '输出图片
                page.Response.Clear()
                page.Response.ContentType = "image/jpeg"
                page.Response.BinaryWrite(stream.ToArray())
            Catch ex As Exception
            Finally
                g.Dispose()
                image.Dispose()

            End Try
        End Sub
    End Class
End Class

新建一个img.aspx的窗体
后台代码如下

Public   Class img Class img
    Inherits System.Web.UI.Page

Web 窗体设计器生成的代码#Region " Web 窗体设计器生成的代码 "

    '该调用是 Web 窗体设计器所必需的。
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()Sub InitializeComponent()

    End Sub

    '注意: 以下占位符声明是 Web 窗体设计器所必需的。
    '不要删除或移动它。
    Private designerPlaceholderDeclaration As System.Object

    Private Sub Page_Init()Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
        'CODEGEN: 此方法调用是 Web 窗体设计器所必需的
        '不要使用代码编辑器修改它。
        InitializeComponent()
    End Sub

#End Region


    Public validates As New Validate.CreatValidateNumber
    Public vali As String

    Private Sub Page_Load()Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        '在此处放置初始化页的用户代码
        vali = validates.CreatValidateNumber(5)
        validates.CreatevalidateGraphic(Me, vali)
        Session("vali") = vali
    End Sub

End Class

调用的HMTL

< HTML >
     < HEAD >
         < title > WebForm1 </ title >
         < meta  name ="GENERATOR"  content ="Microsoft Visual Studio .NET 7.1" >
         < meta  name ="CODE_LANGUAGE"  content ="Visual Basic .NET 7.1" >
         < meta  name ="vs_defaultClientScript"  content ="JavaScript" >
         < meta  name ="vs_targetSchema"  content ="http://schemas.microsoft.com/intellisense/ie5" >
     </ HEAD >
     < body  MS_POSITIONING ="GridLayout" >
         < form  id ="Form1"  method ="post"  runat ="server" >
             < asp:Image  id ="Image1"  style ="Z-INDEX: 101; LEFT: 648px; POSITION: absolute; TOP: 256px"  runat ="server"
                ImageUrl ="img.aspx" ></ asp:Image >
             < asp:TextBox  id ="tb_valide"  style ="Z-INDEX: 102; LEFT: 464px; POSITION: absolute; TOP: 256px"
                runat ="server" ></ asp:TextBox >
             < asp:Button  id ="Button1"  style ="Z-INDEX: 103; LEFT: 560px; POSITION: absolute; TOP: 328px"  runat ="server"
                Text ="Button" ></ asp:Button >
         </ form >
     </ body >
</ HTML >

后台

 

     Private   Sub Button1_Click() Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If tb_valide.Text = Session("vali") Then
            Response.Write("<font color='red'>提示:验证通过</font>")
        Else

            Response.Write("所填写的验证码与所给的不符")
        End If
    End Sub

完成效果如下