JAVA生成验证码代码

生成base64格式图片验证码

/**
     * 验证码的候选内容
     */
    private char codeSequence[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
            'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
            'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
            'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
            'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

 /**
     * 生成验证码
     * 改造生成验证码的方式，将图片base64形式传到前台，而不是直接传验证码到前台
     * @return
     * @throws IOException
     */
    public void imageCode() throws IOException {
        HttpServletResponse resp = CommandContext.getResponse();
        HttpServletRequest req = CommandContext.getRequest();
        String method= req.getMethod();
        if("OPTIONS".equals(method)){
            return ;
        }
        Map map=new HashMap();

        // 在内存中创建图象
        int width = 65, height = 38;
        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(230, 255));
        g.fillRect(0, 0, 100, 40);
        // 设定字体
        g.setFont(new Font("Arial", Font.CENTER_BASELINE | Font.ITALIC, 20));
        // 产生0条干扰线，
        g.drawLine(0, 0, 0, 0);

        //存放验证码
        StringBuffer sRand = new StringBuffer();
        for (int i = 0; i < charCount; i++) {
            String singleCode = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
            sRand.append(singleCode);
            // 将认证码显示到图象中
            g.setColor(getRandColor(100, 150));// 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(singleCode, 14 * i + 5, 25);
        }
        for(int i=0;i<(random.nextInt(5)+5);i++){
            g.setColor(new Color(random.nextInt(255)+1,random.nextInt(255)+1,random.nextInt(255)+1));
            g.drawLine(random.nextInt(70),random.nextInt(40),random.nextInt(70),random.nextInt(40));
            g.drawLine(random.nextInt(70),random.nextInt(40),random.nextInt(70),random.nextInt(40));
        }

        HttpSession session = req.getSession();
        //获取clientid
        String clientId= SystemUtil.getClientId(req);
        if(StringUtils.isEmpty(clientId)){
            //生成clientid
            String userAgent=req.getHeader("User-Agent");
            String sessionId=session.getId();
            String cip= IpPolicy.getClientIP(req);
            clientId=CodeUtil.genClientId(sessionId,cip,userAgent);
        }
        map.put("clientId", clientId);
        if (isValidateCodeCaseSensitive) {
            session.setAttribute("randomCode", sRand.toString());
            SystemUtil.push2Cache(clientId, sRand.toString());
        } else {
            session.setAttribute("randomCode", sRand.toString().toLowerCase());
            SystemUtil.push2Cache(clientId, sRand.toString().toLowerCase());
        }
        // 图象生效
        g.dispose();
        try{

            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            ImageIO.write(image, "jpg", outputStream);
            BASE64Encoder encoder = new BASE64Encoder();
            String base64Img = encoder.encode(outputStream.toByteArray());
            base64Img="data:image/jpg;base64, "+base64Img.replaceAll("
", "").replaceAll("
", "");//删除 
;
            map.put("verCode", base64Img);
            Object jsonObj = JSONSerializer.toJSON(map);
            byte[] json = jsonObj.toString().getBytes("UTF-8");
            resp.setContentType("text/plain;chartset=utf-8");
            resp.setHeader("Cache-Control", "no-cache");
            resp.setHeader("Expires", "0");
            resp.setIntHeader("Content-Length", json.length);
            ServletOutputStream responseOutputStream = resp.getOutputStream();
            responseOutputStream.write(json);
            // 以下关闭输入流！
            responseOutputStream.flush();
            responseOutputStream.close();
            // 获得页面key值
            return ;
        } catch (IOException e) {
            logger.error("生产验证码出错",e);
            throw new SystemException("生产验证码出错",e);
        }
    }


    /**
     * 给定范围获得随机颜色
     *
     * @param fc
     * @param bc
     * @return
     */
    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);
    }