/**

      * 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("\n", "").replaceAll("\r", "");//删除 \r\n;

             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);

     }