1using System;
 2using System.Data;
 3using System.Configuration;
 4using System.Collections;
 5using System.Web;
 6using System.Web.Security;
 7using System.Web.UI;
 8using System.Web.UI.WebControls;
 9using System.Web.UI.WebControls.WebParts;
10using System.Web.UI.HtmlControls;
11using System.Drawing;
12using System.Drawing.Drawing2D;
13
14public partial class ImageCode : System.Web.UI.Page
15...{
16    protected void Page_Load(object sender, EventArgs e)
17    ...{
18        Bitmap bmp = new Bitmap(50, 25);
19        Graphics g = Graphics.FromImage(bmp);
20        Random r = new Random();
21        string code = r.Next(1000, 10000).ToString();
22        Session["code"] = code;
23        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, 50, 25), getColor(), getColor(), 0f);
24        g.DrawString(code, new Font("宋体", 16), brush, 0, 0);
25        Response.ContentType = "image/jpeg";
26        for (int i = 0; i < 150; i++)
27        ...{
28            bmp.SetPixel(r.Next(50), r.Next(25), getColor());
29        }
30        bmp.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
31    }
32    private Color getColor()
33    ...{
34        Random r = new Random();
35        return Color.FromArgb(r.Next(256), r.Next(256), r.Next(256));
36    }
37}
38