vb.net写验证码 vb设计密码验证程序

VB NET 中怎样实现动态验证码

Imports System

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Imports System.Data

Imports System.Configuration

Imports System.Collections

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.Drawing

Partial Public Class VerifyCode

Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

Session("VerifyCode") = MakeValidateCode()

CreateImage(Session("VerifyCode").ToString())

End Sub

Private Sub CreateImage(ByVal checkCode As String)

Dim iwidth As Integer = CInt(checkCode.Length * 12) + 10

Dim image As 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 New Random()

'随机输出噪点

For i As Integer = 0 To 4

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)

Next i

'输出不同字体和颜色的验证码字符

For i As Integer = 0 To checkCode.Length - 1

Dim cindex As Integer = rand.Next(7)

Dim findex As Integer = rand.Next(5)

Dim f As Font = New System.Drawing.Font("宋体", 12, System.Drawing.FontStyle.Regular)

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)

Next i

'画一个边框

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

'输出到浏览器

Dim ms As New System.IO.MemoryStream()

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

Response.ClearContent()

Response.ContentType = "image/Jpeg"

Response.BinaryWrite(ms.ToArray())

g.Dispose()

image.Dispose()

End Sub

Private Function MakeValidateCode() As String

'0 i o

Dim s() As Char = { "0"c, "1"c, "2"c, "3"c, "4"c, "5"c, "6"c, "7"c, "8"c, "9"c, "A"c, "B"c, "C"c, "D"c, "E"c, "F"c, "G"c, "J"c, "K"c, "L"c, "M"c, "N"c, "P"c, "Q"c, "R"c, "S"c, "T"c, "U"c, "V"c, "W"c, "X"c, "Y"c, "Z"c }

Dim num As String = ""

Dim r As New Random()

For i As Integer = 0 To 3

num = s(r.Next(0, s.Length - 1)).ToString()

Next i

Return num

End Function

End Class

求一个vb.net写的验证码？

建一个YanzhenCard.aspx文件

保留%@ Page Language="VB" AutoEventWireup="false" CodeFile="YanzhenCard.aspx.vb" Inherits="YanzhenCard" %,其余删除

如下是代码:

Imports System.IO

Imports System.Drawing

Partial Class YanzhenCard

Inherits System.Web.UI.Page

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Not IsPostBack Then

Dim VNum As String = GenerateRandom(4)

Session("VNum") = VNum

ValidateCode(VNum)

End If

End Sub

Private Sub ValidateCode(ByVal VNum As String)

Dim Gheight As Integer = CType((VNum.Length * 15), Integer)

Dim Img As Bitmap = New Bitmap(Gheight, 20) 'Bitmap是用于处理由像素数据定义的图像

Dim g As Graphics = Graphics.FromImage(Img) 'Graphics.FromImage 从指定的Image创建新的Graphics

g.DrawString(VNum, New Font("Arial", 12), New SolidBrush(Color.Red), 5, 0) 'g.DrawString()在指定位置并且用指定的Brush和Font对象绘制指定的文本字符串。

Dim ms As MemoryStream = New MemoryStream '创建其支持存储区为内存的流。

Img.Save(ms, System.Drawing.Imaging.ImageFormat.Png)

Response.ClearContent()

Response.ContentType = "image/PNG"

Response.BinaryWrite(ms.ToArray)

Response.Write(VNum)

g.Dispose()

Img.Dispose()

Response.End()

End Sub

Private Shared constant As Char() = {"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"}

Public Shared Function GenerateRandom(ByVal Length As Integer) As String

Dim newRandom As System.Text.StringBuilder = New System.Text.StringBuilder(26)

Dim rd As Random = New Random

Dim i As Integer = 0

While i Length

newRandom.Append(constant(rd.Next(26)))

System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)

End While

Return newRandom.ToString

End Function

End Class

调用方法:asp:ImageButton ID="Yanzhengma_Card" runat="server" ImageUrl="YanzhenCard.aspx" Height="20px" Width="75px" BorderColor="#6699cc" BorderStyle="Solid" BorderWidth="1px" /

asp.net vb怎样制作图片验证码

实现过程，在需要调用的页面使用image控件调用验证码生成的页面，验证码生成的页面生成验证图片且将验证信息保存至Session中，调用页面中通过Session判断用户是否输入正确。道理是这样，以下看代码：

生成验证码页面：

gif.ASPx

%@importnamespace="System"%

%@importnamespace="System.io"%

%@importnamespace="System.Drawing"%

%@importnamespace="System.Drawing.Imaging"%

scriptlanguage="VB"runat="server"

SubPage_Load(ByValSenderAsObject,ByValeAsEventArgs)

'RndNum为生成随机码的函数，

DimVNumAsString=RndNum(4)'该值为生成验证码的位数

Session("VNum")=VNum'读取Session

ValidateCode(VNum) '根据Session生成图片

EndSub

'--------------------------------------------

'生成图象验证码函数

SubValidateCode(ByValVNum)

DimImgAsSystem.Drawing.Bitmap

DimgAsGraphics

DimmsAsMemoryStream

DimgheightAsInteger=Int(Len(VNum)*14)

'gheight为图片宽度，根据字符长度自动更改图片宽度

Img=NewBitmap(gheight,24)

g=Graphics.FromImage(Img)

g.DrawString(VNum,(NewFont("Arial",12)),(NewSolidBrush(Color.Red)),3,3)'在矩形内绘制字串（字串，字体，画笔颜色，左上x.左上y）

ms=NewMemoryStream()

Img.Save(ms,ImageFormat.Png)

Response.ClearContent()'需要输出图象信息要修改HTTP头

Response.ContentType="image/Png"

Response.BinaryWrite(ms.ToArray())

g.Dispose()

Img.Dispose()

Response.End()

EndSub

'--------------------------------------------

'函数名称:RndNum

'函数参数:VCodeNum--设定返回随机字符串的位数

'函数功能:产生数字和字符混合的随机字符串

FunctionRndNum(ByValVcodeNum)

DimVcharAsString="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，W，X，Y，Z"'需要使用中文验证，可以修改这里和ValidateCode函数中的字体

DimVcArray()AsString=Split(Vchar,"，")'将字符串生成数组

DimVNumAsString=""

DimiAsByte

Fori=1ToVcodeNum

Randomize()

VNum=VNumVcArray(Int(35*Rnd()))'数组一般从0开始读取，所以这里为35*Rnd

ReturnVNum

EndFunction

/script

调用页面：

demo.ASPx

scriptlanguage="VB"Runat="Server"

SubPage_Load(Senderasobject，easeventargs)

dimVNumasstring=Session("VNum")

Session.Abandon()

ViewState("VNum")=VNum

EndSub

'下面的事件代码是用来测试验证码

SubbtnSubmit_click(senderasobject，easeventargs)

'判断输入的验证码与所给是否相同

IftxtValidateCode.Text=CStr(ViewState("VNum"))Then

ensonShow.text="fontcolor='red'提示:验证通过/font"

Else

ensonShow.text="所填写的验证码与所给的不符"

EndIf

EndSub

/script

html

body

formrunat="server"

divalign="center"

tablewidth="750"

tdvalign="middle"验证码:/td

!--调用验证图片生成页---

tdvalign="top"asp:Imageid="Image1"runat="server"ImageUrl="gif.aspx"//td

/tr

tdvalign="top"输入验证码:/td

tdvalign="top"asp:textboxID="txtValidateCode"runat="server"TextMode="SingleLine"/fontcolor="#FF0000"size="2"*区分大小写/font/td

/tr

tdcolspan="2"valign="top"align="center"asp:buttonID="btnSubmit"runat="server"Text="验证"onclick="btnSubmit_click"/

asp:labelID="ensonShow"runat="server"/

/td

/tr

/table

/div

/form

/body

/html

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