ASP.NET生成验证码
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();
&nb
补充:Web开发 , ASP.Net ,