java使用JWT的方法

{
  "alg": "HS256",    // 指定签名算法
  "typ": "JWT"		 // 指定token令牌类型
}

iss: 发行人
exp: 到期时间
sub: 主题
aud: 用户
nbf: 在此之前不可用
iat: 发布时间
jti: JWT ID用于标识该JWT

Header.Payload.Signature

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

package com.cxstar.utils;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTCreator;
import com.auth0.jwt.alGorithms.Algorithm;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.auth0.jwt.interfaces.JWTVerifier;
import java.util.Calendar;
import java.util.Map;
public class JwtUtil {
    // 签名密钥
    private static final String SECRET = "hello JWT *%$#$&";
    
    public static String generateToken(Map<String,String> payload){
        // 指定token过期时间
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.HOUR, 24);  // 24小时
        JWTCreator.Builder builder = JWT.create();
        // 构建payload
        payload.forEach(builder::withClaim);
        // 指定过期时间和签名算法，并返回token
        String token = builder.withExpiresAt(calendar.getTime()).sign(Algorithm.HMac256(SECRET));
        return token;
    }

    
    public static DecodedJWT decodeToken(String token){
        JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(SECRET)).build();
        DecodedJWT decodedJWT = jwtVerifier.verify(token);
        return decodedJWT;
    }
}

package com.cxstar;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.TokenExpiredException;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.cxstar.utils.JwtUtil;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.HashMap;
import java.util.Map;
@SpringBootTest
class JwtLoginApplicationTests {
    @Test
    void tokenTest() {
        // 根据用户信息生成令牌 --------------------------
        Map<String, String> payload = new HashMap<>();
        payload.put("userId", "233");
        payload.put("userName", "ps");
        String token = JwtUtil.generateToken(payload);
        System.out.println("token: " + token);
        // --------------------------------------------
        // 解析令牌并获取用户信息 ------------------------------------------------
        try {
            DecodedJWT decodedJWT = JwtUtil.decodeToken(token);
            String userId = decodedJWT.getClaim("userId").asString();
            String userName = decodedJWT.getClaim("userName").asString();
            String exp = decodedJWT.getExpiresAt().toString();
            System.out.println("userId: " + userId);      // 取出自定义属性【用户id】
            System.out.println("userName: " + userName);  // 取出自定义属性【用户名】
            System.out.println("exp: " + exp);            // 取出默认属性【过期时间】
        } catch (JWTDecodeException e) {
            System.out.println("令牌错误");
        } catch (TokenExpiredException e) {
            System.out.println("令牌过期");
        }
        // -------------------------------------------------------------------
    }

}