验证码的生成源码

<%@ page contentType="image/jpeg"
 import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
<%!Color getRandColor(int fc, int bc) {
  Random random = new Random();
  if (fc > 255)
   fc = 255;
  if (bc > 255)
   bc = 255;
  int r = fc + random.nextInt(bc - fc);
  int g = fc + random.nextInt(bc - fc);
  int b = fc + random.nextInt(bc - fc);
  return new Color(r, g, b);
 }%>
<%
 response.setHeader("Pragma", "No-cache");
 response.setHeader("Cache-Control", "no-cache");
 response.setDateHeader("Expires", 0);
 try
        {
          int width = 60, height = 20;
          BufferedImage image = new BufferedImage(width, height,
          BufferedImage.TYPE_INT_RGB);
          Graphics g = image.getGraphics();
          Random random = new Random();
          g.setColor(getRandColor(200, 250));
          g.fillRect(0, 0, width, height);

          g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
          g.setColor(getRandColor(160, 200));
          for (int i = 0; i < 155; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
          }
          String sRand = "";
          for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;

            g.setColor(new Color(20 + random.nextInt(110), 20 + random
            .nextInt(110), 20 + random.nextInt(110)));
            g.drawString(rand, 13 * i + 6, 16);
          }
          session.setAttribute("yzm", sRand);
          g.dispose();
          out.clear();
          ImageIO.write(image, "JPEG", response.getOutputStream());
          return;
        }
        catch(Exception ex)
        {
        }
%>