一个自动生成图片验证码的类

下面是类的代码,有一些简单的注释,能看明白了.嘿嘿! Imports System Imports System.Drawing.Drawing2D Imports System.Drawing.imaging Imports System.Drawing Imports System.Web.UI Imports System.IO Namespace Validate Public Class CreatValidateNumber "生成验证码 Public Function CreatValidateNumber(ByVal length As Integer) As String Dim randNumber() As Integer = New Integer(length) {} Dim ValidateNumber() As Integer = New Integer(length) {} Dim ValidateNumberStr As String = "" Dim seekseek As Integer = CInt(DateTime.Now.Second) Dim seekrand As Random = New Random(seekseek) Dim beginseek = Int(seekrand.Next(0, Int32.MaxValue - length * 10000)) Dim seeks() As Integer = New Integer(length) {} Dim i As Integer "生成起始序列值 For i = 0 To length - 1 beginseek += 10000 seeks(i) = beginseek Next "生成随机数字 For i = 0 To length - 1 Dim rand As Random = New Random(seeks(i)) Dim pownum As Integer = 1 * Int(Math.Pow(10, length)) randNumber(i) = rand.Next(pownum, Int32.MaxValue) Next "抽取随机数字 For i = 0 To length - 1 Dim numstr As String = randNumber(i).ToString Dim numlength As Integer = numstr.Length Dim rand As New Random Dim numPosition As Integer = rand.Next(0, numlength - 1) ValidateNumber(i) = Int32.Parse(numstr.Substring(numPosition, 1)) Next "生成验证码 For i = 0 To length - 1 ValidateNumberStr += ValidateNumber(i).ToString Next Return ValidateNumberStr End Function "创建验证码图片 Public 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 Namespace 下面是这个类的引用一个小例子 HTML部份: <%@ Page Language="vb" AutoEventWireup="false" Codebehind="WebForm1.aspx.vb" Inherits="ValidateNumber.WebForm1"%> DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">