BinaryWrite方法输出二进制图像验证码

 1 protected void Page_Load(object sender, EventArgs e)
 2         {
 3             string checkCode = "陌上花开，可缓缓归矣";
 4             //创建画板
 5             System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 20.5)), 22);
 6             Graphics g = Graphics.FromImage(image);//创建Graphics对象
 7             try
 8             {
 9                 Random random = new Random();//生成随机生成器
10                 g.Clear(Color.White);//清空图片背景色
11                 for (int i = 0; i < 2; i++)//画图片的背景噪音线
12                 {
13                     int x1 = random.Next(image.Width);
14                     int x2 = random.Next(image.Width);
15                     int y1 = random.Next(image.Height);
16                     int y2 = random.Next(image.Height);
17                     g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
18                 }
19                 Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
20                 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Gray, Color.DarkBlue, 1.2f, true);
21                 g.DrawString(checkCode, font, brush, 2, 2);
22                 for (int i = 0; i < 100; i++)//画图片的前景噪音点
23                 {
24                     int x = random.Next(image.Width);
25                     int y = random.Next(image.Height);
26                     image.SetPixel(x, y, Color.FromArgb(random.Next()));
27                 }
28                 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
29                 System.IO.MemoryStream ms = new System.IO.MemoryStream();//画图片的边框线
30                 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
31                 Response.ClearContent();
32                 Response.ContentType = "image/Gif";
33                 Response.BinaryWrite(ms.ToArray());
34             }
35             finally
36             {
37                 g.Dispose();
38                 image.Dispose();
39             }
40         }