1、需要引入hutool依赖

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.16</version>
        </dependency>

2、编写工具类

package com.jiawa.train.common.util;

import cn.hutool.core.date.DateField;
import cn.hutool.core.date.DateTime;
import cn.hutool.json.JSONObject;
import cn.hutool.jwt.JWT;
import cn.hutool.jwt.JWTPayload;
import cn.hutool.jwt.JWTUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.HashMap;
import java.util.Map;

/**
 * jwt工具类
 */
public class JwtUtil {
    private static final Logger LOG = LoggerFactory.getLogger(JwtUtil.class);

    /**
     * 盐值很重要，不能泄漏，且每个项目都应该不一样，可以放到配置文件中
     */
    private static final String KEY = "Jiawa12306";

    /**
     * 创建token
     * @param id
     * @param mobile
     * @return
     */
    public static String createToken(Long id, String mobile) {
        DateTime now = DateTime.now();
        DateTime expTime = now.offsetNew(DateField.HOUR, 24);
        Map<String, Object> payload = new HashMap<>();
        // 签发时间
        payload.put(JWTPayload.ISSUED_AT, now);
        // 过期时间
        payload.put(JWTPayload.EXPIRES_AT, expTime);
        // 生效时间
        payload.put(JWTPayload.NOT_BEFORE, now);
        // 内容
        payload.put("id", id);
        payload.put("mobile", mobile);
        String token = JWTUtil.createToken(payload, KEY.getBytes());
        LOG.info("生成JWT token：{}", token);
        return token;
    }

    /**
     * 校验token
     * @param token
     * @return
     */
    public static boolean validate(String token) {
        JWT jwt = JWTUtil.parseToken(token).setKey(KEY.getBytes());
        // validate包含了verify
        boolean validate = jwt.validate(0);
        LOG.info("JWT token校验结果：{}", validate);
        return validate;
    }

    public static JSONObject getJSONObject(String token) {
        JWT jwt = JWTUtil.parseToken(token).setKey(KEY.getBytes());
        JSONObject payloads = jwt.getPayloads();
        payloads.remove(JWTPayload.ISSUED_AT);
        payloads.remove(JWTPayload.EXPIRES_AT);
        payloads.remove(JWTPayload.NOT_BEFORE);
        LOG.info("根据token获取原始内容：{}", payloads);
        return payloads;
    }

    public static void main(String[] args) {
        createToken(1L, "123");

        String token = "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJuYmYiOjE2NzY4OTk4MjcsIm1vYmlsZSI6IjEyMyIsImlkIjoxLCJleHAiOjE2NzY4OTk4MzcsImlhdCI6MTY3Njg5OTgyN30.JbFfdeNHhxKhAeag63kifw9pgYhnNXISJM5bL6hM8eU";
        validate(token);

        getJSONObject(token);
    }
}

3、登录颁发token

package com.jiawa.train.member.service;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.ObjectUtil;
import cn.hutool.core.util.RandomUtil;
import com.jiawa.train.common.exception.BusinessException;
import com.jiawa.train.common.exception.BusinessExceptionEnum;
import com.jiawa.train.common.resp.CommonResp;
import com.jiawa.train.common.resp.MemberLoginResp;
import com.jiawa.train.common.util.JwtUtil;
import com.jiawa.train.common.util.SnowUtil;
import com.jiawa.train.member.domain.Member;
import com.jiawa.train.member.domain.MemberExample;
import com.jiawa.train.member.mapper.MemberMapper;
import com.jiawa.train.member.req.MemberLoginReq;
import com.jiawa.train.member.req.MemberRegisterReq;
import com.jiawa.train.member.req.MemberSendCodeReq;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * @Author lhj
 * @Date 2023-06-02 22:56
 */
@Service
public class MemberService {

    private static final Logger LOG = LoggerFactory.getLogger(MemberService.class);

    @Autowired
    private MemberMapper memberMapper;

    public CommonResp<Long> register(MemberRegisterReq req) {
        String mobile = req.getMobile();
        MemberExample memberExample = new MemberExample();
        memberExample.createCriteria().andMobileEqualTo(mobile);
        List<Member> memberList = memberMapper.selectByExample(memberExample);

        if (CollUtil.isNotEmpty(memberList)) {
            throw new BusinessException(BusinessExceptionEnum.MEMBER_MOBILE_EXIST);
        }

        Member member = new Member();
        member.setId(SnowUtil.getSnowflakeNextId());
        member.setMobile(mobile);
        memberMapper.insert(member);
        return new CommonResp<>(member.getId());
    }


    public CommonResp<Long> sendCode(MemberSendCodeReq req) {
        String mobile = req.getMobile();

        MemberExample memberExample = new MemberExample();
        memberExample.createCriteria().andMobileEqualTo(mobile);
        List<Member> memberList = memberMapper.selectByExample(memberExample);

        if (CollUtil.isEmpty(memberList)) {
            LOG.info("该号码未注册,插入数据库....");
            Member member = new Member();
            member.setId(SnowUtil.getSnowflakeNextId());
            member.setMobile(mobile);
            memberMapper.insert(member);
        }

        String code = RandomUtil.randomNumbers(4);
        LOG.info("手机验证码code:{}......", code);

        return new CommonResp<>();
    }

    public MemberLoginResp login(MemberLoginReq req) {
        String code = req.getCode();
        Member memberDB = selectByMobile(req.getMobile());

        // 如果手机号不存在 抛异常
        if (ObjectUtil.isNull(memberDB)) {
            throw new BusinessException(BusinessExceptionEnum.MEMBER_MOBILE_NOT_EXIST);
        }

        // 校验短信验证码
        if (!"8888".equals(code)) {
            throw new BusinessException(BusinessExceptionEnum.MEMBER_MOBILE_CODE_ERROR);
        }

        // Bean赋值 从memberDB对象中获取属性值，并将其设置到memberLoginResp对象中对应的属性中。
        MemberLoginResp memberLoginResp = BeanUtil.copyProperties(memberDB, MemberLoginResp.class);

        // 颁发token
        String token = JwtUtil.createToken(memberLoginResp.getId(), memberLoginResp.getMobile());
        memberLoginResp.setToken(token);
        return memberLoginResp;
    }


    private Member selectByMobile(String mobile) {
        MemberExample memberExample = new MemberExample();
        memberExample.createCriteria().andMobileEqualTo(mobile);
        List<Member> list = memberMapper.selectByExample(memberExample);
        if (CollUtil.isEmpty(list)) {
            return null;
        } else {
            return list.get(0);
        }
    }
}