Java JWT example

 

package com.codewalla.hrms.authentication.controller;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jws;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.security.Keys;

import java.security.Key;
import java.security.SecureRandom;
import java.util.Base64;
import java.util.Date;

public class JWTExample {
    public static void main(String[] args) {
        int keyLengthBytes = 64;
        SecureRandom secureRandom = new SecureRandom();
        byte[] keyBytes = new byte[keyLengthBytes];
        secureRandom.nextBytes(keyBytes);

        String secretKey = Base64.getUrlEncoder().withoutPadding().encodeToString(keyBytes);

        String jws = Jwts.builder()
                .setSubject("user123")
                .setIssuer("example.com")
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + 3600000)) // 1 hour expiration
                .signWith(SignatureAlgorithm.HS256,secretKey)
                .compact();

        System.out.println("Generated JWT: " + jws);

        try {
            Jws<Claims> claimsJws = Jwts.parser()
                    .setSigningKey(secretKey)
                    .parseClaimsJws(jws);
            Claims claims = claimsJws.getBody();
            System.out.println("Subject: " + claims.getSubject());
            System.out.println("Issuer: " + claims.getIssuer());
            System.out.println("Expiration: " + claims.getExpiration());
        } catch (Exception e) {
            System.out.println("Invalid JWT: " + e.getMessage());
        }
    }
}