1 protected void Page_Load(object sender, EventArgs e) 2 3 { 4 5 CreateCheckCodeImage(GenerateCheckCode()); 6 7 } 8 9 10 11 private string GenerateCheckCode() 12 13 { 14 15 int number; 16 17 char code; 18 19 string checkCode = String.Empty; 20 21 System.Random random = new Random(); 22 23 24 25 for (int i = 0; i < 4; i++) 26 27 { 28 29 number = random.Next(); 30 31 32 33 if (number % 2 == 0) 34 35 code = (char)('0' + (char)(number % 10)); 36 37 else 38 39 code = (char)('A' + (char)(number % 26)); 40 41 42 43 checkCode += code.ToString(); 44 45 } 46 47 Response.Cookies.Add(new HttpCookie("CheckCode", checkCode)); 48 49 return checkCode; 50 51 } 52 53 54 55 private void CreateCheckCodeImage(string checkCode) 56 57 { 58 59 if (checkCode == null || checkCode.Trim() == String.Empty) 60 61 return; 62 63 System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); 64 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 76 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); 88 89 int y1 = random.Next(image.Height); 90 91 int y2 = random.Next(image.Height); 92 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); 110 111 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(); 122 123 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); 124 125 Response.ClearContent(); 126 127 Response.ContentType = "image/Gif"; 128 129 Response.BinaryWrite(ms.ToArray()); 130 131 } 132 133 finally 134 135 { 136 137 g.Dispose(); 138 139 image.Dispose(); 140 141 } 142 143 }