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("\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);
     }