java使用jwt

1、添加依赖jwt

<dependency>
    <groupId>com.auth0</groupId>
    <artifactId>java-jwt</artifactId>
    <version>3.10.3</version>
</dependency>

2、新建JwtUtil类

package com.example.demo.config.shiro;

import cn.hutool.core.date.DateField;
import cn.hutool.core.date.DateUtil;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTCreator;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.interfaces.DecodedJWT;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.util.Date;

@Component
@Slf4j
public class JwtUtil {
    @Value("${emos.jwt.secret}")
    private String secret;

    @Value("${emos.jwt.expire}")
    private int expire;

    /**
     * 创建token
     */
    public String createToken(int userId){
        Date date = DateUtil.offset(new Date(), DateField.DAY_OF_YEAR, 5);
        Algorithm algorithm = Algorithm.HMAC256(secret);
        JWTCreator.Builder builder = JWT.create();
        String token = builder.withClaim("userId", userId)
                .withExpiresAt(date).sign(algorithm);
        return token;
    }
    /**
     * 获取用户ID
     */
    public int getUserId(String token){
        DecodedJWT jwt = JWT.decode(token);
        int userId = jwt.getClaim("userId").asInt();
        return userId;
    }
    /**
     * 校验token
     */
    public void verifyToken(String token){
        Algorithm algorithm = Algorithm.HMAC256(secret);
        JWTVerifier jwtVerifier = JWT.require(algorithm).build();
        jwtVerifier.verify(token);
    }
}