利用谷歌 kaptcha 进行验证码生成

 package main.com.smart.controller;
 
 import com.google.code.kaptcha.Producer;
 import main.com.smart.utils.CaptchaProducer;
 import main.com.smart.utils.RedisClient;
 import org.apache.log4j.Logger;
 import org.apache.log4j.spi.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.servlet.ModelAndView;
 
 import javax.imageio.ImageIO;
 import javax.servlet.ServletOutputStream;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 
 import com.google.code.kaptcha.Constants;
 
 import java.awt.image.BufferedImage;
 
 /**
  * 验证码 生成控制器
  *
  * @author yang ming
  * @create 2016-04-29 12:17
  */
 
 @Controller
 @RequestMapping("/kaptcha")
 public class CaptchaController {
     /**
      * 使用方法
      * get: http://localhost:8080/smart/kaptcha
      */
     private static final Logger log = Logger.getLogger(CaptchaController.class);
     @Autowired
     private Producer captchaProducer = null;
 
     @RequestMapping
     public ModelAndView getKaptchaImage(HttpServletRequest request, HttpServletResponse response) throws Exception {
         RedisClient client = RedisClient.getInstance();
         //在控制器中获取验证码
         //String kaptchaExpected = (String) request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
         log.info("获取验证");
 
         log.info(Constants.KAPTCHA_SESSION_KEY);
         HttpSession session = request.getSession();
         String code1 = client.getValue(Constants.KAPTCHA_SESSION_KEY);
         String code = String.valueOf(session.getAttribute(Constants.KAPTCHA_SESSION_KEY));
         //System.out.println("******************验证码是: " + code + "******************");
 
         response.setDateHeader("Expires", 0);
 
         // Set standard HTTP/1.1 no-cache headers.
         response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
 
         // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
         response.addHeader("Cache-Control", "post-check=0, pre-check=0");
 
         // Set standard HTTP/1.0 no-cache header.
         response.setHeader("Pragma", "no-cache");
 
         // return a jpeg
         response.setContentType("image/jpeg");
 
         // create the text for the image
         String[] array = CaptchaProducer.getCaptchaText();
         //String capText = captchaProducer.createText();
         //int param1 = (int)capText.charAt(0);
         //int param2 = (int)capText.charAt(1);
         Integer result =  Integer.valueOf(array[0]) + Integer.valueOf(array[1]);
 
         // store the text in the session
         client.setValue(Constants.KAPTCHA_SESSION_KEY, result.toString());
         //session.setAttribute(Constants.KAPTCHA_SESSION_KEY, result);
 
         // create the image with the text
         BufferedImage bi = captchaProducer.createImage(array[0]+"+"+array[1]+"=?");
         ServletOutputStream out = response.getOutputStream();
 
         // write the data out
         ImageIO.write(bi, "jpg", out);
         try {
             out.flush();
         } finally {
             out.close();
         }
         return null;
     }
 
 }