<%@ page language="java" pageEncoding="UTF-8"%>
<%@ pagecontentType
="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*,com.swetake.util.Qrcode"%>
<%!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);
}%>
<%
//设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);

//    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("Comic    Sans    MS", Font.PLAIN, 20));

//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 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 + 6, 16);
}

//    将认证码存入SESSION
session.setAttribute("rand", sRand);

//    图象生效
g.dispose();
out.clear();
out = pageContext.pushBody();

//    输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>

 

注:要先下载com.swetake.util.Qrcode包