生成验证码，vb.net

生成图片验证码的代码(vb.net版)

Imports System

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

Imports System.IO

Imports System.Drawing

'生成图片验证码类

Public Class CreateImage

Public Sub CreateImage()

End Sub

Public Shared Sub DrawImage()

Dim img As CreateImage = New CreateImage()

HttpContext.Current.Session("CheckCode") = Global.CreateImage.RndNum(4)

Global.CreateImage.CreateImages(HttpContext.Current.Session("CheckCode").ToString())

End Sub

''' <summary>

''' 生成验证图片

'''</summary>

'''<param name="checkCode">验证字符</param>

Public Shared Sub CreateImages(ByVal checkCode As String)

Dim iwidth As Integer = CType(checkCode.Length * 13, Integer)

Dim image As System.Drawing.Bitmap = New System.Drawing.Bitmap(iwidth, 25)

Dim g As Graphics = Graphics.FromImage(image)

g.Clear(Color.White)

'定义颜色

Dim c As Color() = {Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple}

'定义字体

Dim font As String() = {"Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体"}

Dim rand As Random = New Random()

Dim i As Integer = 0

Do While i < 50

Dim x As Integer = rand.Next(image.Width)

Dim y As Integer = rand.Next(image.Height)

g.DrawRectangle(New Pen(Color.LightGray, 0), x, y, 1, 1)

i += 1

Loop

i = 0

Do While i < checkCode.Length

Dim cindex As Integer = rand.Next(7)

Dim findex As Integer = rand.Next(5)

Dim f As Font = New System.Drawing.Font(font(findex), 10, System.Drawing.FontStyle.Bold)

Dim b As Brush = New System.Drawing.SolidBrush(c(cindex))

Dim ii As Integer = 4

If (i + 1) Mod 2 = 0 Then

ii = 2

End If

g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii)

i += 1

Loop

'画一个边框

g.DrawRectangle(New Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1)

Dim ms As System.IO.MemoryStream = New System.IO.MemoryStream()

image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg)

HttpContext.Current.Response.ClearContent()

HttpContext.Current.Response.ContentType = "image/Jpeg"

HttpContext.Current.Response.BinaryWrite(ms.ToArray())

g.Dispose()

image.Dispose()

End Sub

''' <summary>

''' 生成随机的字母

''' </summary>

''' <param name="VcodeNum">生成字母的个数</param>

''' <returns>string</returns>

Public Shared Function RndNum(ByVal VcodeNum As Integer) As String

Dim allChar As String = "0,1,2,3,4,5,6,7,8,9"

Dim allCharArray() As String = allChar.Split(",")

Dim randomCode As String = ""

Dim temp As Integer = -1

Dim rand As Random = New Random

Dim i As Integer = 0

Do While (i < VcodeNum)

If (temp <> -1) Then

Dim aa As Integer = CType(DateTime.Now.Ticks Mod System.Int32.MaxValue, Integer) '根据时间生成随机数种子

rand = New Random(aa)

End If

Dim t As Integer = rand.Next(61) + 1

If t > allCharArray.Length - 1 Then t = allCharArray.Length - 1

If temp = t Then '抑制产生连续重复的验证码。

i -= 1

randomCode = Microsoft.VisualBasic.Left(randomCode, i)

End If

temp = t

randomCode = randomCode + allCharArray(t)

i += 1

Loop

Return randomCode

End Function

End Class

生成图片验证码,请指教!