java生成验证码图片

　　　　<dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.7.7</version>
        </dependency> 

 

import cn.hutool.cache.CacheUtil;
import cn.hutool.cache.impl.TimedCache;
import cn.hutool.captcha.CaptchaUtil;
import cn.hutool.captcha.ShearCaptcha;

import lombok.SneakyThrows;

　　

//登录失败次数
    public static final Integer LOGIN_FAIL_NUM = 4;
    //拒绝再次登录得次数
    public static final Integer LOGIN_REFUSE_NUM = 10;
    //缓存登录图片验证码
    public static final TimedCache<String, String> CODE_CACHE = CacheUtil.newTimedCache(1000*60*5);
    //缓存登录失败次数
    public static final TimedCache<String, Integer> LOGIN_FAIL_CACHE = CacheUtil.newTimedCache(1000*60*20);

    public DataCallBackController(){
        //定期清理缓存
        CODE_CACHE.schedulePrune(3000);
        LOGIN_FAIL_CACHE.schedulePrune(1000*60*5);
    }
    @SneakyThrows
    public void getCode(@RequestParam String username, HttpServletResponse response) {

        //定义图形验证码的长、宽、验证码字符数、干扰线宽度
        ShearCaptcha captcha = CaptchaUtil.createShearCaptcha(12,50,4,2);
        //图形验证码结果存缓存
        CODE_CACHE.put(username, captcha.getCode());
        //图形验证码写出到流
        captcha.write(response.getOutputStream());
    }