[收藏]生成校验图片

生成校验图片

1 图片生成类

public class EncryptImage {

 public String sRand = "";

 public 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);
 }

 public BufferedImage creatImage() {

  // 在内存中创建图象
  int width = 60, height = 20;
  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, 18));

  //画边框
  //g.setColor(new Color());
  //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 rand = request.getParameter("rand");
  //rand = rand.substring(0,rand.indexOf("."));

  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
   //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.setColor(new Color(20 + random.nextInt(110), 20 + random
     .nextInt(110), 20 + random.nextInt(110)));
   g.drawString(rand, 13 * i + 6, 16);
  }
  // 图象生效
  g.dispose();
  return image;
 }
 /**
  * @return Returns the sRand.
  */
 public String getSRand() {
  return sRand;
 }
 /**
  * @param rand The sRand to set.
  */
 public void setSRand(String rand) {
  sRand = rand;
 }
}

2 servlet输出

public class EImage extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.addHeader("Content-Type", "image/jpeg");
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        EncryptImage ei = new EncryptImage();
        BufferedImage img = ei.creatImage();
        request.getSession(true).setAttribute("ecode", ei.getSRand());
        ImageIO.write(img, "JPEG", response.getOutputStream());
    }
}

3 通过session中的ecode进行校验