import java.awt.image.BufferedImage;  import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;  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 com.google.code.kaptcha.Constants;
import com.google.code.kaptcha.Producer;  @Controller
public class CaptchaImageCreateController {  private Producer captchaProducer = null;  @Autowired  public void setCaptchaProducer(Producer captchaProducer){  this.captchaProducer = captchaProducer;  }  @RequestMapping("/kaptcha.jpg")  public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception{  // Set to expire far in the past.  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 capText = captchaProducer.createText();  // store the text in the session  request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);  // create the image with the text  BufferedImage bi = captchaProducer.createImage(capText);  ServletOutputStream out = response.getOutputStream();  // write the data out  ImageIO.write(bi, "jpg", out);  try {  out.flush();  } finally {  out.close();  }  return null;  }
}   

/** * ClassName: LoginController <br/> * Function: 登录Controller. <br/> */
@Controller
@RequestMapping("/login")
public class LoginController {  /** * loginCheck:ajax异步校验登录请求. <br/> * * @param request * @param username 用户名 * @param password 密码 * @param kaptchaReceived 验证码 * @return 校验结果 */  @RequestMapping(value = "check", method = RequestMethod.POST)  @ResponseBody  public String loginCheck(HttpServletRequest request,  @RequestParam(value = "username", required = true) String username,  @RequestParam(value = "password", required = true) String password,  @RequestParam(value = "kaptcha", required = true) String kaptchaReceived){  //用户输入的验证码的值  String kaptchaExpected = (String) request.getSession().getAttribute(  com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);  //校验验证码是否正确  if (kaptchaReceived == null || !kaptchaReceived.equals(kaptchaExpected)) {  return "kaptcha_error";//返回验证码错误  }  //校验用户名密码  // ……  // ……  return "success"; //校验通过返回成功  }
}