/**
 * 接收验证码请求
 */
@RequestMapping(value="captchacode")
public void CaptchaCode(){
  try {
    CaptchaCodeModel captchaCodeModel=new CaptchaCode().getCode();
    //将验证码放到Session中
    HttpServletRequest httpServletRequest=super.getRequest();
    httpServletRequest.getSession().setAttribute("captchacodekey", captchaCodeModel.getCaptchaCode());
    //将图片写到客户端 
    HttpServletResponse httpServletResponse=super.getResponse();
    //禁止缓存
    httpServletResponse.setHeader("Pragma", "no-cache");
    httpServletResponse.setHeader("Cache-Control", "no-cache");
    httpServletResponse.setDateHeader("Expires", 0);
    ServletOutputStream servletOutputStream=httpServletResponse.getOutputStream();
    //输出图片
    ImageIO.write(captchaCodeModel.getCaptchaImage(), "jpeg", servletOutputStream);
    servletOutputStream.close();
  } catch (Exception e) {
    logger.info("验证码生成失败:"+e.getMessage());
  }
}

public class CaptchaCode {
private int width = 90;// 定义图片的width
private int height = 20;// 定义图片的height
private int codeCount = 4;// 定义图片上显示验证码的个数
private int xx = 15;
private int fontHeight = 18;
private int codeY = 16;
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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

public CaptchaCodeModel getCode() throws IOException {
  // 定义图像buffer
  BufferedImage buffImg = new BufferedImage(width, height,
      BufferedImage.TYPE_INT_RGB);
  Graphics gd = buffImg.getGraphics();
  // 创建一个随机数生成器类
  Random random = new Random();
  // 将图像填充为白色
  gd.setColor(Color.WHITE);
  gd.fillRect(0, 0, width, height);
  // 创建字体，字体的大小应该根据图片的高度来定。
  Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
  // 设置字体。
  gd.setFont(font);
  // 画边框。
  gd.setColor(Color.BLACK);
  gd.drawRect(0, 0, width - 1, height - 1);
  // 随机产生40条干扰线，使图象中的认证码不易被其它程序探测到。
  gd.setColor(Color.BLACK);
  for (int i = 0; i < 40; i++) {
    int x = random.nextInt(width);
    int y = random.nextInt(height);
    int xl = random.nextInt(12);
    int yl = random.nextInt(12);
    gd.drawLine(x, y, x + xl, y + yl);
  }
  // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
  StringBuffer randomCode = new StringBuffer();
  int red = 0, green = 0, blue = 0;
  // 随机产生codeCount数字的验证码。
  for (int i = 0; i < codeCount; i++) {
    // 得到随机产生的验证码数字。
    String code = String.valueOf(codeSequence[random.nextInt(36)]);
    // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
    red = random.nextInt(255);
    green = random.nextInt(255);
    blue = random.nextInt(255);
    // 用随机产生的颜色将验证码绘制到图像中。
    gd.setColor(new Color(red, green, blue));
    gd.drawString(code, (i + 1) * xx, codeY);
    // 将产生的四个随机数组合在一起。
    randomCode.append(code);
  }
  CaptchaCodeModel captchaCodeModel=new CaptchaCodeModel();
  captchaCodeModel.setCaptchaCode(randomCode.toString());
  captchaCodeModel.setCaptchaImage(buffImg);
  return captchaCodeModel;
}
public class CaptchaCodeModel{
  //验证码的String形式
  private String captchaCode;
  //验证码的图片形式
  private BufferedImage captchaImage;
  public String getCaptchaCode() {
    return captchaCode;
  }
  public void setCaptchaCode(String captchaCode) {
    this.captchaCode = captchaCode;
  }
  public BufferedImage getCaptchaImage() {
    return captchaImage;
  }
  public void setCaptchaImage(BufferedImage captchaImage) {
    this.captchaImage = captchaImage;
  }
}

/**
* 验证验证码
*/
@RequestMapping(value = "valicatpcha")
public void register_R() {
PageData pageData = super.getPageData();
  // 获取验证码
  String captchaCode = pageData.getString("captchacode");
  HttpServletRequest httpServletRequest = super.getRequest();
  Object codeObject = httpServletRequest.getSession().getAttribute(“captchacodekey”);
  // 验证码错误
  if (codeObject == null
      || Tools.isEmptyString(captchaCode)
      || !String.valueOf(codeObject).toUpperCase()
          .equals(captchaCode.toUpperCase())) {
    setResult(
        MessageManager.getInstance().getMessage("invalidcaptcha"),
        ResultType.Error);
    return;
  }
}

function validcaptchacode(captchaCode) {
$.ajax({
type : "POST",
url : "valicatpcha",
data : {
captchacode : captchaCode,
tm : new Date().getTime()
},
dataType : "json",
cache : false,
success : function(data) {
alert(data);
},
error : function(data) {
alert(data); }
});
}