第一种方法：使用一般处理程序Handler 　

第一步：准备工作, 做一张验证码底图图片，放在程序的一个文件夹内，例如app_data内

第二步：添加一般处理程序ImageHandler，继承IHttpHandler,System.Web.SessionState.IRequiresSessionState

第三步：添加处理程序，代码如下

1

using System;
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using System.Collections.Generic;
3

using System.Linq;
4

using System.Web;
5

6

namespace AA
7

{
8

///

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/// 生成验证码程序
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///

11

12

public class ImageHandler : IHttpHandler,System.Web.SessionState.IRequiresSessionState
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{
14

15

public void ProcessRequest(HttpContext context)
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{
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context.Response.ContentType = "image/jpeg";
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string path = "~/app_data/code.jpg";
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string filepath = context.Server.MapPath(path);
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System.Drawing.Image image = System.Drawing.Image.FromFile(filepath);
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// 使用随机数生成随机数
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//System.Random random = new Random();
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//int code = random.Next(1000, 10000);
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//string codeString = code.ToString();
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// 借助 Guid 生成随机验证码
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System.Guid guid = System.Guid.NewGuid();
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string codeString = guid.ToString().Substring(0, 4); //截取四位
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// 使用会话状态
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context.Session["Code"] = codeString;
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using (System.Drawing.Graphics g
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= System.Drawing.Graphics.FromImage(image))
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{
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g.DrawString(
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codeString,
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new System.Drawing.Font("Arial", 14),
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System.Drawing.Brushes.Blue,
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3, 3);
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} //将验证码写到图片上
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context.Response.ContentType = "image/jpeg";
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image.Save(
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context.Response.OutputStream,
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System.Drawing.Imaging.ImageFormat.Jpeg
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);
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}
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46

public bool IsReusable
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{
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get
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{
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return false;
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}
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}
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}
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}

第四步：页面添加引用，注意Form必须有runat="server"标记

<asp:Image ID="Image1" ImageUrl="~/ImageHandler.ashx" runat="server" />

第二种方法使用验证码类，可以自由定义长度，字体等

第一步：定义一个验证码类，封装验证码的各个属性，代码如下

1

using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Drawing;
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using System.Web;
7

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public class VerifyCode
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{
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#region 验证码长度(默认5个验证码的长度)
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int length = 5;
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public int Length
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{
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get { return length; }
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set { length = value; }
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}
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#endregion
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#region 验证码字体大小(默认10像素)
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int fontSize = 10;
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public int FontSize
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{
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get { return fontSize; }
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set { fontSize = value; }
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}
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#endregion
27

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#region 边框补(默认1像素)
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int padding = 1;
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public int Padding
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{
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get { return padding; }
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set { padding = value; }
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}
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#endregion
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37

#region 是否输出燥点(默认不输出)
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bool chaos = true;
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public bool Chaos
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{
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get { return chaos; }
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set { chaos = value; }
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}
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#endregion
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#region 输出燥点的颜色(默认灰色)
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Color chaosColor = Color.LightGray;
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public Color ChaosColor
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{
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get { return chaosColor; }
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set { chaosColor = value; }
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}
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#endregion
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55

#region 自定义背景色(默认白色)
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Color backgroundColor = Color.White;
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public Color BackgroundColor
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{
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get { return backgroundColor; }
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set { backgroundColor = value; }
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}
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#endregion
63

64

#region 自定义随机颜色数组
65

Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
66

public Color[] Colors
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{
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get { return colors; }
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set { colors = value; }
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}
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#endregion
72

73

#region 自定义字体数组
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string[] fonts = { "Arial", "Georgia" };
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public string[] Fonts
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{
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get { return fonts; }
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set { fonts = value; }
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}
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#endregion
81

82

83

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#region 自定义随机码字符串序列(使用逗号分隔)
85

string codeSerial = "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,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";
86

public string CodeSerial
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{
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get { return codeSerial; }
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set { codeSerial = value; }
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}
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#endregion
92

93

#region 生成校验码图片
94

public Bitmap CreateImageCode(string code)
95

{
96

int fSize = FontSize;
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int fWidth = fSize + Padding;
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int imageWidth = (int)(code.Length * fWidth) + 4 + Padding * 2;
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int imageHeight = fSize * 2 + Padding;
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System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageWidth, imageHeight);
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Graphics g = Graphics.FromImage(image);
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g.Clear(BackgroundColor);
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Random rand = new Random();
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//给背景添加随机生成的燥点
105

if (this.Chaos)
106

{
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Pen pen = new Pen(ChaosColor, 0);
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int c = Length * 10;
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for (int i = 0; i < c; i++)
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{
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int x = rand.Next(image.Width);
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int y = rand.Next(image.Height);
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g.DrawRectangle(pen, x, y, 1, 1);
114

}
115

}
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int left = 0, top = 0, top1 = 1, top2 = 1;
117

int n1 = (imageHeight - FontSize - Padding * 2);
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int n2 = n1 / 4;
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top1 = n2;
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top2 = n2 * 2;
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Font f;
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Brush b;
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int cindex, findex;
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//随机字体和颜色的验证码字符
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for (int i = 0; i < code.Length; i++)
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{
127

cindex = rand.Next(Colors.Length - 1);
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findex = rand.Next(Fonts.Length - 1);
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f = new System.Drawing.Font(Fonts[findex], fSize, System.Drawing.FontStyle.Bold);
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b = new System.Drawing.SolidBrush(Colors[cindex]);
131

if (i % 2 == 1)
132

{
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top = top2;
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}
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else
136

{
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top = top1;
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}
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left = i * fWidth;
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g.DrawString(code.Substring(i, 1), f, b, left, top);
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}
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//画一个边框边框颜色为Color.Gainsboro
143

g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1);
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g.Dispose();
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return image;
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}
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#endregion
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149

#region 将创建好的图片输出到页面
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public void CreateImageOnPage(string code, HttpContext context)
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{
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System.IO.MemoryStream ms = new System.IO.MemoryStream();
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Bitmap image = this.CreateImageCode(code);
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image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
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context.Response.ClearContent();
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context.Response.ContentType = "image/Jpeg";
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context.Response.BinaryWrite(ms.GetBuffer());
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ms.Close();
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ms = null;
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image.Dispose();
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image = null;
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}
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#endregion
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#region 生成随机字符码
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public string CreateVerifyCode(int codeLen)
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{
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if (codeLen == 0)
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{
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codeLen = Length;
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}
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string[] arr = CodeSerial.Split(',');
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string code = "";
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int randValue = -1;
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Random rand = new Random(unchecked((int)DateTime.Now.Ticks));
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for (int i = 0; i < codeLen; i++)
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{
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randValue = rand.Next(0, arr.Length - 1);
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code += arr[randValue];
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}
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return code;
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}
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public string CreateVerifyCode()
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{
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return CreateVerifyCode(0);
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}
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#endregion
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}

第三步：添加一个验证码页面Code.aspx,添加引用VerifyCode类的程序集，注意命名空间的是否添加了没有

后台代码添加如下：

1

using System;
2

using System.Collections.Generic;
3

using System.Linq;
4

using System.Web;
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using System.Web.UI;
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using System.Web.UI.WebControls;
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using System.Drawing;
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using VerifyCode类的命名空间;
9

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public partial class Code: System.Web.UI.Page
11

{
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#region 验证码长度(默认5个验证码的长度)
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int length = 5;
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#endregion
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#region 验证码字体大小(默认10像素)
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int fontSize = 12;
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#endregion
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#region 边框补(默认1像素)
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int padding = 1;
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#endregion
23

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#region 是否输出燥点(默认输出)
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bool chaos = true;
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#endregion
27

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#region 输出燥点的颜色(默认灰色)
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Color chaosColor = System.Drawing.Color.Pink;
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#endregion
31

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#region 自定义背景色(默认白色)
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Color backgroundColor = Color.White;
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#endregion
35

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#region 自定义随机颜色数组
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Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
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#endregion
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40

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#region 自定义字体数组
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string[] fonts = { "Arial", "Georgia" };
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#endregion
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#region 自定义随机码字符串序列(使用逗号分隔)
46

string codeSerial = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
47

#endregion
48

49

protected void Page_Load(object sender, EventArgs e)
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{
51

VerifyCode v = new VerifyCode();
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v.Length = this.length;
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v.FontSize = this.fontSize;
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v.Chaos = this.chaos;
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v.BackgroundColor = this.backgroundColor;
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v.ChaosColor = this.chaosColor;
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v.CodeSerial = this.codeSerial;
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v.Colors = this.colors;
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v.Fonts = this.fonts;
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v.Padding = this.padding;
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string code = v.CreateVerifyCode(); //取随机码
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v.CreateImageOnPage(code, this.Context); // 输出图片
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Session["CheckCode"] = code.ToLower(); // 使用Session["CheckCode"]取验证码的值
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//Response.Cookies.Add(new HttpCookie("CheckCode", code.ToLower()));// 使用Cookies取验证码的值
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}
66

}
67

第三步：在验证码引用页面添加代码

<asp:Image id="Image1" runat="server" ImageUrl="~/Code.aspx">asp:Image>

ITPub博客

验证码生成二三例（一般处理程序，封装一个类）

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ITPub博客

验证码 生成 二三例（一般处理程序，封装一个类）

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验证码生成二三例（一般处理程序，封装一个类）