[Java] JWT(Json Web Token)

pom.xml

implementation("io.jsonwebtoken:jjwt:0.12.3")

SecretKey

SecretKey key = new SecretKeySpec(
    "key는-256-bits-이상이어야함".getBytes(StandardCharsets.UTF_8),
    Jwts.SIG.HS256.key().build().getAlgorithm()
);

Encoding

String jwt = Jwts.builder()
    .signWith(key)
    .expiration(new Date(System.currentTimeMillis() + 24 * 60 * 60 * 1000))
    .subject("student")
    .claim("name", "john")
    .claim("age", 25)
    .compact();

System.out.println(jwt);

eyJhbGciOiJIUzM4NCJ9.eyJleHAiOjE1OTkwNTg1ODIsInN1YiI6InN0dWRlbnQiLCJuYW1lIjoiam9obiIsImFnZSI6MjV9.zqkbBnFdS8LSjlYfUWypDVnRTiPNmk7WSTbAc9II1Twq6UQVQgwn9QTqvjLXnLP-

Decoding

String jwt = "eyJhbGciOiJIUzM4NCJ9.eyJleHAiOjE1OTkwNTg1ODIsInN1YiI6InN0dWRlbnQiLCJuYW1lIjoiam9obiIsImFnZSI6MjV9.zqkbBnFdS8LSjlYfUWypDVnRTiPNmk7WSTbAc9II1Twq6UQVQgwn9QTqvjLXnLP-";

Claims claims = Jwts.parser()
    .verifyWith(key)
    .build()
    .parseSignedClaims(jwt)
    .getPayload();

System.out.println(claims.getSubject());
System.out.println(claims.get("name"));
System.out.println(claims.get("age"));
System.out.println(claims.get("email"));

student
john
25
null