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!