JWT 实现

1. 导入依赖

   <dependency>    <groupId>com.auth0</groupId>    <artifactId>java-jwt</artifactId>    <version>3.18.2</version></dependency>

2. 创建令牌

   public static String secretKey = "!QAZ@123#asd.$";@Testpublic void JWTCreatTest(){    Map<String, Object> map = new HashMap<>();    Calendar instance = Calendar.getInstance();    //7天后过期    instance.add(Calendar.DATE,7);    String token = JWT.create().withHeader(map) .withClaim("userId",1) .withClaim("userName","WuYufan") .withExpiresAt(instance.getTime()) .sign(Algorithm.HMAC256(secretKey));    System.out.println(token);}

   生成的令牌：

   eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyTmFtZSI6Ild1WXVmYW4iLCJleHAiOjE2MzI3MTk3MTYsInVzZXJJZCI6MX0.uFkoaDEIqOtHj6P8IFosE809fu4V5PgG2ezSczc9mlY

   withHeader：添加标头(Header)

   withClaim：添加有效载荷(Payload)

   withExpiresAt：设置过期时间

   sign：添加签名(Signature) ； Algorithm.HMAC256 为加密算法

3. 根据令牌和签名解析数据

   @Testpublic void getInfoByToken(){    //创建验证对象    JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(secretKey)).build();    //验证对象根据 token 获取DecodedJWT对象，该对象可以读取token中的数据    DecodedJWT verify = jwtVerifier.verify("eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyTmFtZSI6Ild1WXVmYW4iLCJleHAiOjE2MzI3MTk3MTYsInVzZXJJZCI6MX0.uFkoaDEIqOtHj6P8IFosE809fu4V5PgG2ezSczc9mlY");    Integer userId = verify.getClaim("userId").asInt();    String userName = verify.getClaim("userName").asString();    //过期时间    Date expirationTime = verify.getExpiresAt();    System.out.println("userId = " + userId);    System.out.println("userName = " + userName);    System.out.println("expirationTime = " + expirationTime);}

   运行结果：

   userId = 1userName = WuYufanexpirationTime = Mon Sep 27 13:15:16 CST 2021

常见异常：

• SignatureverificationException : 签名不一致异常
• TokenExpiredException: 令牌过期异常
• AlgorithmNismatchException: 算法不匹配异常
• InvalidClaimException : 失效的payload异常

编写 JWT 工具类

package cn.edu.hziee.boot.utils;import com.auth0.jwt.JWT;import com.auth0.jwt.JWTCreator;import com.auth0.jwt.algorithms.Algorithm;import com.auth0.jwt.interfaces.DecodedJWT;import java.util.Calendar;import java.util.Map;public class JWTUtils {// 密钥    private static final String SECRETKEY = "!QAzxZ@12^3#asd.$01.0..";    /     * 获取令牌     * @param map 填入的用户信息     * @return token 生成的令牌     */    public static String getToken(Map<String, Object> map){ Calendar instance = Calendar.getInstance(); instance.add(Calendar.DATE,7); //创建 JWT builder JWTCreator.Builder builder = JWT.create(); map.forEach((k,v)->{ builder.withClaim(k,v); });  String token = builder.withExpiresAt(instance.getTime())  .sign(Algorithm.HMAC256(SECRETKEY)); return token;    }    /     * 验证 token 的合法性，并返回其信息     * @param token 需要验证的 token     * @return 返回 token 信息（DecodedJWT 对象）     */    public static DecodedJWT verify(String token){ return JWT.require(Algorithm.HMAC256(SECRETKEY)).build().verify(token);    }}