valid_nmb.aspx.vb

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Imports System.IO
Imports System.Drawing.Imaging
Public Class valid_nmb
    Inherits System.Web.UI.Page

#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()

    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(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

    Private 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
        Dim vnum As String = rndnum(4)
        Session("vnum") = vnum
        validatecode(UCase(vnum))
    End Sub

    Sub validatecode(ByVal vnum)
        Dim img As System.Drawing.Bitmap
        Dim g As Graphics
        Dim ms As MemoryStream
        Dim gheight As Integer = Int(Len(vnum) * 11.5)
        img = New Bitmap(gheight, 20)
        g = Graphics.FromImage(img)
        g.DrawString(vnum, (New Font("arial", 10)), (New SolidBrush(Color.Blue)), 3, 3)
        ms = New MemoryStream
        img.Save(ms, ImageFormat.Png)
        Response.ClearContent()
        Response.ContentType = "image/png"
        Response.BinaryWrite(ms.ToArray())
        g.Dispose()
        img.Dispose()
        Response.End()
    End Sub

    Function rndnum(ByVal vcodenum)
        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,v,w,x,y,z"
        Dim vcarray() As String = Split(vchar, ",")
        Dim vnum As String = ""
        Dim i As Byte
        For i = 1 To vcodenum
            Randomize()
            vnum = vnum & vcarray(Int(35 * Rnd()))
        Next
        Return vnum
    End Function

End Class