1、存放在session中
@RequestMapping("captcha")
public void captcha(HttpServletRequest request, HttpServletResponse response,HttpSession session) throws IOException{
//禁止图像缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 设置响应的类型格式为图片格式
response.setContentType("image/jpeg");
// 生成随机字串
String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
// 生成图片
int w = 135, h = 40;
VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode);
redisTemplate.opsForValue().set("",verifyCode.toLowerCase());
// 将验证码存储在session以便登录时校验
session.setAttribute(CAPTCHA_KEY, verifyCode.toLowerCase());
}
2、存放在redis中
我们知道，redis可以设置数据的有效时间，存放在redis一方面可以减轻服务器的压力，另一方面，我们可以不用手动去清除数据
@RequestMapping("captcha_bak")
public void redisCaptcha(HttpServletRequest request, HttpServletResponse response) throws IOException{
//禁止图像缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 设置响应的类型格式为图片格式
response.setContentType("image/jpeg");
// 生成随机字串
String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
// 生成图片
int w = 135, h = 40;
VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode);
redisTemplate.opsForValue().set(Redis_Captcha,verifyCode.toLowerCase());
redisTemplate.expire(Redis_Captcha,60,TimeUnit.SECONDS);
}