package org.linlinjava.litemall.wx.service;

import org.linlinjava.litemall.wx.util.JwtHelper;

/**
 * 维护用户token
 */
public class UserTokenManager {
    public static String generateToken(Integer id) {
        JwtHelper jwtHelper = new JwtHelper();
        return jwtHelper.createToken(id);
    }
    public static Integer getUserId(String token) {
        JwtHelper jwtHelper = new JwtHelper();
        Integer userId = jwtHelper.verifyTokenAndGetUserId(token);
        if(userId == null || userId == 0){
            return null;
        }
        return userId;
    }
}

package org.linlinjava.litemall.wx.util;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTCreationException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.Claim;
import com.auth0.jwt.interfaces.DecodedJWT;

public class JwtHelper {
    // 秘钥
    static final String SECRET = "X-Litemall-Token";
    // 签名是有谁生成
    static final String ISSUSER = "LITEMALL";
    // 签名的主题
    static final String SUBJECT = "this is litemall token";
    // 签名的观众
    static final String AUDIENCE = "MINIAPP";
    
    
    public String createToken(Integer userId){
        try {
            Algorithm algorithm = Algorithm.HMAC256(SECRET);
            Map<String, Object> map = new HashMap<String, Object>();
            Date nowDate = new Date();
            // 过期时间：2小时
            Date expireDate = getAfterDate(nowDate,0,0,0,2,0,0);
            map.put("alg", "HS256");
            map.put("typ", "JWT");
            String token = JWT.create()
                // 设置头部信息 Header
                .withHeader(map)
                // 设置 载荷 Payload
                .withClaim("userId", userId)
                .withIssuer(ISSUSER)
                .withSubject(SUBJECT)
                .withAudience(AUDIENCE)
                // 生成签名的时间 
                .withIssuedAt(nowDate)
                // 签名过期的时间 
                .withExpiresAt(expireDate)
                // 签名 Signature
                .sign(algorithm);
            return token;
        } catch (JWTCreationException exception){
            exception.printStackTrace();
        }
        return null;
    }
    
    public Integer verifyTokenAndGetUserId(String token) {
        try {
            Algorithm algorithm = Algorithm.HMAC256(SECRET);
            JWTVerifier verifier = JWT.require(algorithm)
                .withIssuer(ISSUSER)
                .build();
            DecodedJWT jwt = verifier.verify(token);
            Map<String, Claim> claims = jwt.getClaims();
            Claim claim = claims.get("userId");
            return claim.asInt();
        } catch (JWTVerificationException exception){
//            exception.printStackTrace();
        }
        
        return 0;
    }
    
    public  Date getAfterDate(Date date, int year, int month, int day, int hour, int minute, int second){
        if(date == null){
            date = new Date();
        }
        
        Calendar cal = new GregorianCalendar();
        
        cal.setTime(date);
        if(year != 0){
            cal.add(Calendar.YEAR, year);
        }
        if(month != 0){
            cal.add(Calendar.MONTH, month);
        }
        if(day != 0){
            cal.add(Calendar.DATE, day);
        }
        if(hour != 0){
            cal.add(Calendar.HOUR_OF_DAY, hour);
        }
        if(minute != 0){
            cal.add(Calendar.MINUTE, minute);
        }
        if(second != 0){
            cal.add(Calendar.SECOND, second);
        }
        return cal.getTime();
    }
    
}

<dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.4.1</version>
        </dependency>