验证码生成

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验证码生成代码：

package com.test.web;@WebServlet("/WEB-INF/content/authImg.jsp")public class AuthImage extends HttpServlet {    private static final long serialVersionUID = 1L;    // 定义图形验证码中绘制字符的字体        private final Font mFont =            new Font("Arial Black", Font.PLAIN, 16);        // 定义图形验证码的大小        private final int IMG_WIDTH = 100;        private final int IMG_HEIGTH = 18;        // 定义一个获取随机颜色的方法        private 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);            // 得到随机颜色            return new Color(r , g , b);        }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // 设置禁止缓存                response.setHeader("Pragma","No-cache");                response.setHeader("Cache-Control","no-cache");                response.setDateHeader("Expires", 0);                response.setContentType("image/jpeg");                BufferedImage image = new BufferedImage                    (IMG_WIDTH , IMG_HEIGTH , BufferedImage.TYPE_INT_RGB);                Graphics g = image.getGraphics();                Random random = new Random();                g.setColor(getRandColor(200 , 250));                // 填充背景色                g.fillRect(1, 1, IMG_WIDTH - 1, IMG_HEIGTH - 1);                // 为图形验证码绘制边框                g.setColor(new Color(102 , 102 , 102));                g.drawRect(0, 0, IMG_WIDTH - 1, IMG_HEIGTH - 1);                g.setColor(getRandColor(160,200));                // 生成随机干扰线                for (int i = 0 ; i < 30 ; i++)                {                    int x = random.nextInt(IMG_WIDTH - 1);                    int y = random.nextInt(IMG_HEIGTH - 1);                    int xl = random.nextInt(6) + 1;                    int yl = random.nextInt(12) + 1;                    g.drawLine(x , y , x + xl , y + yl);                }                g.setColor(getRandColor(160,200));                // 生成随机干扰线                for (int i = 0 ; i < 30 ; i++)                {                    int x = random.nextInt(IMG_WIDTH - 1);                    int y = random.nextInt(IMG_HEIGTH - 1);                    int xl = random.nextInt(12) + 1;                    int yl = random.nextInt(6) + 1;                    g.drawLine(x , y , x - xl , y - yl);                }                // 设置绘制字符的字体                g.setFont(mFont);                // 用于保存系统生成的随机字符串                String sRand = "";                for (int i = 0 ; i < 6 ; i++)                {                    String tmp = getRandomChar();                    sRand += tmp;                    // 获取随机颜色                    g.setColor(new Color(20 + random.nextInt(110)                        ,20 + random.nextInt(110)                        ,20 + random.nextInt(110)));                    // 在图片上绘制系统生成的随机字符                    g.drawString(tmp , 15 * i + 10,15);                }                // 获取HttpSesssion对象                HttpSession session = request.getSession(true);                // 将随机字符串放入HttpSesssion对象中                session.setAttribute("rand" , sRand);                g.dispose();                // 向输出流中输出图片                ImageIO.write(image, "JPEG", response.getOutputStream());    }    // 定义获取随机字符串方法        private String getRandomChar()        {            // 生成一个0、1、2的随机数字            int rand = (int)Math.round(Math.random() * 2);            long itmp = 0;            char ctmp = '\u0000';            switch (rand)            {                // 生成大写字母                case 1:                    itmp = Math.round(Math.random() * 25 + 65);                    ctmp = (char)itmp;                    return String.valueOf(ctmp);                // 生成小写字母                case 2:                    itmp = Math.round(Math.random() * 25 + 97);                    ctmp = (char)itmp;                    return String.valueOf(ctmp);                // 生成数字                default :                    itmp = Math.round(Math.random() * 9);                    return  itmp + "";            }        }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }}
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