How to create and verify JWT Token in Java

Add JWT library in pom.xml

<!-- pom.xml -->
<!-- JWT Token Creation Library -->
<dependency>
    <groupId>com.auth0</groupId>
    <artifactId>java-jwt</artifactId>
    <version>3.4.0</version>
</dependency>

Create JWT Token

public static String generateJWTToken() {
    String signatureSecret = "SECRET_VALUE_FOR_SIGNATURE";
    Algorithm algorithm = Algorithm.HMAC256(signatureSecret);

    Calendar c = Calendar.getInstance();
    Date currentDate = c.getTime();

    c.add(Calendar.HOUR, 24);
    Date expireDate = c.getTime();

    String jwtToken = JWT.create()
            .withIssuer("smoothprogramming")
            .withSubject("demo")
            .withAudience("techgeeks")
            .withIssuedAt(currentDate)
            .withExpiresAt(expireDate)
            .withClaim("Claim1", "Value1")
            .withClaim("Claim2", "Value2")
            .sign(algorithm);

    return jwtToken;
}

Verify JWT Token

Verify method verifies and decode the JWT token. If verification fails then it throws an exception.

public static void verifyJWTToken(String jwtToken) {
    String signatureSecret = "SECRET_VALUE_FOR_SIGNATURE";
    Algorithm algorithm = Algorithm.HMAC256(signatureSecret);

    JWTVerifier verifier = JWT.require(algorithm)
            .withIssuer("smoothprogramming")
            .withSubject("demo")
            .build();

    DecodedJWT decodedJWT = verifier.verify(jwtToken);
    System.out.println("Claim1 is "+ decodedJWT.getClaim("Claim1").asString());
    System.out.println("Claim2 is "+ decodedJWT.getClaim("Claim2").asString());
}

Decode JWT Token

There are times when you don’t want to verify the token, but want to extract the content of the JWT token. In this case, you dont need a secret to extract JWT token’s content.

public static void decodeJWTToken(String jwtToken) {
    DecodedJWT decodedJWT = JWT.decode(jwtToken);
    System.out.println("Claim1 is "+ decodedJWT.getClaim("Claim1").asString());
    System.out.println("Claim2 is "+ decodedJWT.getClaim("Claim2").asString());
}

Code

Find the code at Github Repo.

References:
https://jwt.io/