动态生成验证码
知识点：
1. 对图像的操作
问题：
动态生成验证码
解决方案
1 <%@ WebHandler Language="C#" Class="ValidateCode" %> 2 3 using System; 4 using System.Web; 5 using System.Drawing; 6 using System.IO; 7 8 public class ValidateCode : IHttpHandler { 9 10 public void ProcessRequest (HttpContext context) { 11 context.Response.ContentType = "text/plain"; 12 //context.Response.Write("Hello World"); 13 Random r = new Random(); 14 int n = r.Next(10000,100000); 15 CreateValidateGraphic(n.ToString(),context); 16 } 17 /// <summary> 18 /// 创建验证码的图片 19 /// </summary> 20 /// <param name="containsPage">要输出到的page对象</param> 21 /// <param name="validateNum">验证码</param> 22 public void CreateValidateGraphic(string validateCode, HttpContext context) 23 { 24 Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22); 25 Graphics g = Graphics.FromImage(image); 26 try 27 { 28 //生成随机生成器 29 Random random = new Random(); 30 //清空图片背景色 31 g.Clear(Color.White); 32 //画图片的干扰线 33 for (int i = 0; i < 25; i++) 34 { 35 int x1 = random.Next(image.Width); 36 int x2 = random.Next(image.Width); 37 int y1 = random.Next(image.Height); 38 int y2 = random.Next(image.Height); 39 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2); 40 } 41 Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic)); 42 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), 43 Color.Blue, Color.DarkRed, 1.2f, true); 44 g.DrawString(validateCode, font, brush, 3, 2); 45 //画图片的前景干扰点 46 for (int i = 0; i < 100; i++) 47 { 48 int x = random.Next(image.Width); 49 int y = random.Next(image.Height); 50 image.SetPixel(x, y, Color.FromArgb(random.Next())); 51 } 52 //画图片的边框线 53 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); 54 //保存图片数据 55 MemoryStream stream = new MemoryStream(); 56 image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg); 57 //输出图片流 58 context.Response.Clear(); 59 context.Response.ContentType = "image/jpeg"; 60 context.Response.BinaryWrite(stream.ToArray()); 61 } 62 finally 63 { 64 g.Dispose(); 65 image.Dispose(); 66 } 67 } 68 69 public bool IsReusable { 70 get { 71 return false; 72 } 73 } 74 75 }
