1 protected void Page_Load(object sender, EventArgs e)
2
3 {
4
5 CreateCheckCodeImage(GenerateCheckCode());
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7 }
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9
10
11 private string GenerateCheckCode()
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13 {
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15 int number;
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17 char code;
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19 string checkCode = String.Empty;
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21 System.Random random = new Random();
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23
24
25 for (int i = 0; i < 4; i++)
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27 {
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29 number = random.Next();
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31
32
33 if (number % 2 == 0)
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35 code = (char)('0' + (char)(number % 10));
36
37 else
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39 code = (char)('A' + (char)(number % 26));
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41
42
43 checkCode += code.ToString();
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45 }
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47 Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
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49 return checkCode;
50
51 }
52
53
54
55 private void CreateCheckCodeImage(string checkCode)
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57 {
58
59 if (checkCode == null || checkCode.Trim() == String.Empty)
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61 return;
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63 System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
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65 Graphics g = Graphics.FromImage(image);
66
67 try
68
69 {
70
71 //生成随机生成器
72
73 Random random = new Random();
74
75 //清空图片背景色
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77 g.Clear(Color.White);
78
79 //画图片的背景噪音线
80
81 for (int i = 0; i < 2; i++)
82
83 {
84
85 int x1 = random.Next(image.Width);
86
87 int x2 = random.Next(image.Width);
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89 int y1 = random.Next(image.Height);
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91 int y2 = random.Next(image.Height);
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93 g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
94
95 }
96
97 Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
98
99 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
100
101 g.DrawString(checkCode, font, brush, 2, 2);
102
103 //画图片的前景噪音点
104
105 for (int i = 0; i < 100; i++)
106
107 {
108
109 int x = random.Next(image.Width);
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111 int y = random.Next(image.Height);
112
113 image.SetPixel(x, y, Color.FromArgb(random.Next()));
114
115 }
116
117 //画图片的边框线
118
119 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
120
121 System.IO.MemoryStream ms = new System.IO.MemoryStream();
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123 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
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125 Response.ClearContent();
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127 Response.ContentType = "image/Gif";
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129 Response.BinaryWrite(ms.ToArray());
130
131 }
132
133 finally
134
135 {
136
137 g.Dispose();
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139 image.Dispose();
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141 }
142
143 }
