【验证码】asp.net 验证码的简单制作(vb.net+C#)

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asp.net 验证码的简单制作(vb.net+C#)

Public Class ValidationCode
Implements IHttpHandler
'随机发生器
Shared r As New Random(Guid.NewGuid().GetHashCode())
'排除黑色、透明色颜色，因为底色黑色
Shared colors As PropertyInfo()=(GetType(Brushes).GetProperties(System.Reflection.BindingFlags.[Public] Or System.Reflection.BindingFlags.GetProperty Or System.Reflection.BindingFlags.[Static])).Where(Function(p) p.Name <> "Black" AndAlso p.Name <> "Transparent").[Select](Function(p) p).ToArray()
'排除黑色颜色，因为底色黑色
Shared linecolors As PropertyInfo()=(GetType(Pens).GetProperties(System.Reflection.BindingFlags.[Public] Or System.Reflection.BindingFlags.GetProperty Or System.Reflection.BindingFlags.[Static])).Where(Function(p) p.Name <> "Black").[Select](Function(p) p).ToArray()
'获取静态类Brushes实例对象
Shared colorobj As Object=GetType(Brushes).GetConstructor(BindingFlags.NonPublic, Nothing, Type.EmptyTypes, Nothing)
'获取静态类Pens实例对象
Shared penobj As Object=GetType(Pens).GetConstructor(BindingFlags.NonPublic, Nothing, Type.EmptyTypes, Nothing)
'每个随机字符的宽度
Const PERNUMBERWIDTH As Single=40F
'每个字符的高度
Const PERNUMBERHEIGHT As Single=50F
Public Sub ProcessRequest(context As HttpContext)
'获取要产生多少随机数（默认产生5个）
Dim reqNum As Integer=5
If context.Request.QueryString("reqNum") IsNot Nothing Then
Integer.TryParse(context.Request.QueryString("reqNum"), reqNum)
End If
'产生多少大的背景图
Dim bt As New Bitmap(CInt(Math.Truncate(PERNUMBERWIDTH * reqNum)), CInt(Math.Truncate(PERNUMBERHEIGHT)))
Dim g As Graphics=Graphics.FromImage(bt)
'产生4个随机数（number可以被保存到Session中）
Dim numbers As String=""
'绘制数字
For i As Integer=1 To reqNum
numbers +=r.[Next](0, 9).ToString()
Dim color=DirectCast(colors.GetValue(r.[Next](0, colors.Length)), PropertyInfo)
context.Response.Write(Convert.ToString(color.Name) & "<br/>")
Dim randomcolor As Brush=DirectCast(color.GetValue(colorobj, Nothing), Brush)
g.DrawString(numbers(i - 1).ToString(), New Font("黑体", PERNUMBERWIDTH), randomcolor, New PointF((i - 1) * PERNUMBERWIDTH, 0F))
Next
'绘制随机线条
Dim linenum As Integer=r.[Next](10, 21)
For i As Integer=1 To linenum
Dim linecolor=DirectCast(linecolors.GetValue(r.[Next](0, colors.Length)), PropertyInfo)
Dim randomcolor As Pen=DirectCast(linecolor.GetValue(penobj, Nothing), Pen)
g.DrawLine(randomcolor, New PointF(CSng(r.NextDouble() * PERNUMBERWIDTH * reqNum), CSng(r.NextDouble() * PERNUMBERHEIGHT)), New PointF(CSng(r.NextDouble() * PERNUMBERWIDTH * reqNum), CSng(r.NextDouble() * PERNUMBERHEIGHT)))
Next
g.Dispose()
context.Response.Clear()
context.Response.ContentType="image/jpeg"
bt.Save(context.Response.OutputStream, ImageFormat.Jpeg)
bt.Dispose()
context.Response.[End]()
End Sub
Public ReadOnly Property IsReusable() As Boolean
Get
Return False
End Get
End Property
End Class

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