1  <tr>
2                   <td height="40" align="right">验证码：</td>
3                   <td><input type="text" name="codenames" id="code" class="cinput">
4                 <img src="showshouye" style="margin-top: -25px;margin-left: 70;">
5               </td>

public String execute() throws Exception {  response.setContentType("image/jpeg");  response.setHeader("Pragma", "No-cache");  response.setHeader("Cache-Control", "no-cache");  response.setDateHeader("Expires", 0);  HttpSession session = request.getSession();  // 在内存中创建图象  int width = 70, height = 23;  BufferedImage image = new BufferedImage(width, height,  BufferedImage.TYPE_INT_RGB);  // 获取图形上下文  Graphics g = image.getGraphics();  // 生成随机类  Random random = new Random();  // 设定背景色  g.setColor(getRandColor(200, 250));  g.fillRect(0, 0, width, height);  // 设定字体  g.setFont(new Font("Times New Roman", Font.PLAIN, 24));  // 画边框  g.setColor(getRandColor(160, 200));  g.drawRect(0, 0, width - 1, height - 1);  // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到  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);  }  // 取随机产生的认证码(4位数字)  String sRand = "";  for (int i = 0; i < 4; i++) {  String rand = String.valueOf(random.nextInt(10));  sRand += rand;  // 将认证码显示到图象中  g.setColor(new Color(20 + random.nextInt(110), 20 + random  .nextInt(110), 20 + random.nextInt(110)));  // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成  g.drawString(rand, 13 * i + 14, 20);  }  // 将认证码存入SESSION  session.setAttribute("verifyCode", sRand);  // 图象生效  g.dispose();  // 输出图象到页面  ImageIO.write(image, "JPEG", response.getOutputStream());  return null;  }  private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色  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);  }