ASP.NET生成验证码

潘玮柏上快乐大本营,斯廷坎普,小妞刘小阳

生成验证码原理：产生随机字符，并将字符生成为图片，同时储存到Session里去，然后验证用户输入的内容是否与Session中的验证码相符即可。
 
效果图：用户可以点击切换验证码信息。
 
 
一般处理程序：CheckCodeHandler.cs
 
  1 <%@ WebHandler Language="C#" Class="CheckCodeHandler" %>
  2
  3 using System;
  4 using System.Web;
  5 using System.Text;
  6 using System.Drawing;
  7 using System.Web.SessionState;
  8
  9 public class CheckCodeHandler : IHttpHandler,IRequiresSessionState
 10 {
 11
 12     //产生验证码的字符集
 13     public string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y";
 14    
 15     public void ProcessRequest (HttpContext context) {
 16         string validateCode = CreateRandomCode(4);
 17         context.Session["ValidateCode"] = validateCode;//将验证码保存到session中
 18         CreateCodeImage(validateCode, context);
 19     }
 20 
 21     public bool IsReusable {
 22         get {
 23             return false;
 24         }
 25     }
 26
 27     /// <summary>
 28     /// 生成验证码
 29     /// </summary>
 30     /// <param name="n">验证码个数</param>
 31     /// <returns>验证码字符串</returns>
 32     public string CreateRandomCode(int n)
 33     {
 34         string[] CharArray = charcode.Split(',');//将字符串转换为字符数组
 35         string randomCode = "";
 36         int temp = -1;
 37
 38         Random rand = new Random();
 39         for (int i = 0; i < n; i++)
 40         {
 41             if (temp != -1)
 42             {
 43                 rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
 44             }
 45             int t = rand.Next(CharArray.Length - 1);
 46             if (temp != -1 && temp == t)
 47             {
 48                 return CreateRandomCode(n);
 49             }
 50             temp = t;
 51             randomCode += CharArray[t];
 52         }
 53         return randomCode;
 54     }
 55
 56     public void CreateCodeImage(string checkCode, HttpContext context)
 57     {
 58         int iwidth = (int)(checkCode.Length * 13);
 59         System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
 60         Graphics g = Graphics.FromImage(image);
 61         Font f = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Italic | System.Drawing.FontStyle.Bold));
 62
 63         // 前景色
 64         Brush b = new System.Drawing.SolidBrush(Color.Black);
 65
 66         // 背景色
 67         g.Clear(Color.White);
 68
 69         // 填充文字
 70         g.DrawString(checkCode, f, b, 0, 1);
 71
 72         // 随机线条
 73        
 74         Pen linePen = new Pen(Color.Gray, 0);
 75         Random rand = new Random();
 76    
 77         for (int i = 0; i < 5; i++)
 78         {
 79             int x1 = rand.Next(image.Width);
 80             int y1 = rand.Next(image.Height);
 81             int x2 = rand.Next(image.Width);
 82             int y2 = rand.Next(image.Height);
 83             g.DrawLine(linePen, x1, y1, x2, y2);
 84         }
 85       
 86         // 随机点
 87         for (int i = 0; i < 30; i++)
 88         {
 89             int x = rand.Next(image.Width);
 90             int y = rand.Next(image.Height);
 91             image.SetPixel(x, y, Color.Gray);
 92         }
 93
 94         // 边框
 95         g.DrawRectangle(new Pen(Color.Gray), 0, 0, image.Width - 1, image.Height - 1);
 96
 97         // 输出图片
 98         System.IO.MemoryStream ms = new System.IO.MemoryStream();
 99         image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
100         context.Response.ClearContent();
101         context.Response.ContentType = "image/jpeg";
102         context.Response.BinaryWrite(ms.ToArray());
103         g.Dispose();
104         image.Dispose();
105     }
106 }
 
 
封装成类库：ValidateNumber.cs
 
  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Web;
  5 using System.Drawing;
  6 using System.Web.UI;
  7 using System.Drawing.Drawing2D;
  8 using System.IO;
  9 using System.Drawing.Imaging;
 10
 11 /// <summary>
 12 ///ValidateNumber 生成验证码
 13 /// </summary>
 14 public class ValidateNumber
 15 {
 16     //产生验证码的字符集 （易混淆的字符去掉）
 17     private string charcode = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y,a,b,c,d,e,f,g,h,j,k,m,n,p,r,s,u,w,x,y";
 18
 19     /// <summary>
 20     /// 验证码的最大长度
 21     /// </summary>
 22     public int MaxLength
 23     {
 24         get { return 10; }
 25     }
 26
 27     /// <summary>
 28     /// 验证码的最小长度
 29     /// </summary>
 30     public int MinLength
 31     {
 32         get { return 1; }
 33     }
 34
 35     /// <summary>
 36     /// 生成验证码
 37     /// </summary>
 38     /// <param name="length">指定验证码的长度</param>
 39     /// <returns></returns>
 40     public string CreateValidateNumber(int length)
 41     {
 42         string[] CharArray = charcode.Split(',');//将字符串转换为字符数组
 43         string randomCode = "";
 44         int temp = -1;
 45
 46         Random rand = new Random();
 47         for (int i = 0; i < length; i++)
 48         {
 49             if (temp != -1)
 50             {
 51                 rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
 52             }
 53             int t = rand.Next(CharArray.Length - 1);
 54             if (temp != -1 && temp == t)
 55             {
 56                 return CreateValidateNumber(length);
 57             }
 58             temp = t;
 59             randomCode += CharArray[t];
 60         }
 61         return randomCode;
 62     }
 63
 64     /// <summary>
 65     /// 创建验证码的图片
 66     /// </summary>
 67     /// <param name="context">context对象</param>
 68     /// <param name="validateNum">验证码</param>
 69     public void CreateValidateGraphic(HttpContext context,string validateNum)
 70     {
 71         int iwidth = (int)(validateNum.Length * 14);
 72         Bitmap image = new Bitmap(iwidth, 22);
 73         Graphics g = Graphics.FromImage(image);
 74         try
 75         {
 76             //生成随机生成器
 77             Random random = new Random();
 78             //清空图片背景色
 79             g.Clear(Color.White);
 80             //画图片的干扰线
 81             for (int i = 0; i < 25; i++)
 82             {
 83                 int x1 = random.Next(image.Width);
 84                 int x2 = random.Next(image.Width);
 85                 int y1 = random.Next(image.Height);
 86                 int y2 = random.Next(image.Height);
 87                 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
 88             }
 89             Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
 90             LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
 91              Color.Blue, Color.DarkRed, 1.2f, true);
 92             g.DrawString(validateNum, font, brush, 3, 2);
 93             //画图片的前景干扰点
 94             for (int i = 0; i < 100; i++)
 95             {
 96                 int x = random.Next(image.Width);
 97                 int y = random.Next(image.Height);
 98                 image.SetPixel(x, y, Color.FromArgb(random.Next()));
 99             }
100             //画图片的边框线
101             g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
102             //保存图片数据
103             MemoryStream stream = new MemoryStream();
104             image.Save(stream, ImageFormat.Jpeg);
105             //输出图片
106             context.Response.Clear();
107             context.Response.ContentType = "image/jpeg";
108             context.Response.BinaryWrite(stream.ToArray());
109         }
110         finally
111         {
112             g.Dispose();
113             image.Dispose();
114         }
115     }
116     /// <summary>
117     /// 得到验证码图片的长度
118     /// </summary>
119     /// <param name="validateNumLength">验证码的长度</param>
120     /// <returns></returns>
121     public static int GetImageWidth(int validateNumLength)
122     {
123         return (int)(validateNumLength * 14);
124     }
125     /// <summary>
126     /// 得到验证码图片的高度
127     /// </summary>
128     /// <returns></returns>
129     public static double GetImageHeight()
130     {
131         return 22;
132     }
133 }
 
 
示例下载：
 

 

 

作者： ForEvErNoME

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