后台代码
1 protected void Page_Load(object sender, EventArgs e)
2 {
3 Bitmap bitmap = CreateBitmap(GetRandomDigit(2)+GetRandomNumbers(2));
4 bitmap.Save(Response.OutputStream, ImageFormat.Jpeg);
5 bitmap.Dispose();
6 }
7 #region 数字验证
8 public string GetRandomDigit(int len)
9 {
10 string str = "1234567890";
11 string strResult = "";
12 Random random = new Random(unchecked((int)DateTime.Now.Ticks));
13 for (int i = 0; i < len; i++)
14 {
15 strResult +=str[random.Next(0,10)].ToString();
16 }
17 return strResult;
18 }
19 #endregion
20
21
22 #region 字母验证
23 public string GetRandomNumbers(int len)
24 {
25 string str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
26 String strResult = "";
27 Random random = new Random();
28 for (int i = 0; i < len; i++)
29 {
30 strResult += str[random.Next(0, 10)].ToString();
31 }
32 return strResult;
33 }
34
35 #endregion
36
37
38 public Bitmap CreateBitmap(string check)
39 {
40 int width = (int)(check.Length * 12);
41 Bitmap bitmap = new Bitmap(width, 20);
42 Graphics graphics = Graphics.FromImage(bitmap);
43 graphics.Clear(Color.White);
44 Color[] c ={ Color.Black,Color.Red, Color.DarkBlue, Color.Green, Color.Brown, Color.DarkCyan,Color.Purple};
45 string[] font = { "Verdana","Microsoft Sans Serif","Comic Sans MS","Arial","宋体"};
46 Random random = new Random();
47 for (int i = 0; i < 30; i++)
48 {
49 int x1 = random.Next(bitmap.Width);
50 int x2 = random.Next(bitmap.Width);
51 int y1 = random.Next(bitmap.Height);
52 int y2 = random.Next(bitmap.Height);
53 graphics.DrawLine(new Pen(Color.LightGray, 1), new Point(x1, y1), new Point(x2, y2));
54
55 }
56 for (int i = 0; i < check.Length; i++)
57 {
58 int cIndex = random.Next(c.Length-1);
59 int fIndex = random.Next(font.Length);
60 Font f = new Font(font[fIndex].ToString(),10, FontStyle.Regular);
61 Brush b = new SolidBrush(c[cIndex]);
62 int ii = 4;
63 if ((i +1)% 2 == 0)
64 {
65 ii = 2;
66 }
67 graphics.DrawString(check.Substring(i, 1), f, b, new PointF(3 + (i * 12 ), ii));
68 }
69 graphics.Flush();
70
71 return bitmap;
72 }
前台： <img src="Default.aspx" onclick="this.src=this.src+'?'" alt="验证码" />