java-jwt通过公钥字符串验证解析token方式

<!-- java-jwt -->
<dependency>
    <groupId>com.auth0</groupId>
    <artifactId>java-jwt</artifactId>
    <version>4.2.1</version>
</dependency>

/**
 * 根据公钥字符串生成PublicKey对象
 * @return
 * @throws NoSuchAlgorithmException
 * @throws InvalidKeySpecException
 */
private static PublicKey getPublicKey()
        throws NoSuchAlgorithmException, InvalidKeySpecException {

    String pem = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAuWCkZn1ksPM+DBLzgaffe2je6/Kr168fDI/CAM23Ardh4+w5yprtCmNfibCLcNZ66OzPC164p4ufboc9fxXqd5mv0ZtaHGG2pATH5e7z+Gla3Bd3QX8WqJi5LkAtsdP23IQqhz8UHA+Vmd6pTzobcQBhF1K7K/zcK9QDTFon4tCxL12wSOl40CDlWnaHortvljmJ5T3zD1iPjHjpVejI5YQReqxXEuqFVTqu2nhdTWAmfX8KrlVbPGPCevruKFmNvnl09N0Kk2CZGRlLq5aE7UZxH3GOkNWKkVWMO7tUgoJK9r8v/EIrIcuO5SX7RuyyhyY0/fsx3f+CTrUATkfgVwIDAQAB";
    X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(pem));
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    PublicKey publicKey = keyFactory.generatePublic(pubKeySpec);
    System.out.println(publicKey);
    return publicKey;
}

/**
 * 校验token
 * @param token
 * @return
 * @throws Exception
 */
public static DecodedJWT verifierToken(String token)throws Exception{

    
    //其实按照规定只需要传递 publicKey 来校验即可，这可能是auth0 的缺点
    Algorithm algorithm = Algorithm.RSA256((RSAPublicKey) getPublicKey(),null);
    JWTVerifier verifier = JWT.require(algorithm)
            //.withIssuer(ISSUER)
            .build(); //Reusable verifier instance 可复用的验证实例
    DecodedJWT jwt = verifier.verify(token);


    return jwt;

}

@SpringBootTest(classes = KeycloakdemoApplication.class)
@RunWith(SpringRunner.class)
public class DemoTest {

    @Test
    public void testGetInstance() throws Exception {
        DecodedJWT verify = JWTUtils.verifierToken("eyJhbGciOiJSUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA6ICIxdGtoMFBXanE1SmpOalVjc1hNYnJ1TldQVngtM2tQekJpekJGTDZfUDFJIn0.eyJleHAiOjE2NzM0NTc3MjYsImlhdCI6MTY3MzQ1NzQyNiwiYXV0aF90aW1lIjoxNjczNDU2MTU1LCJqdGkiOiJiMDZlNDljNS1kMTk5LTQ4ZWItYWE4NS1iNWJjMTMxNDVhMWIiLCJpc3MiOiJodHRwOi8vbG9jYWxob3N0OjgwODEvYXV0aC9yZWFsbXMvbXlSZWFsbSIsInN1YiI6ImI4ZTAwM2Y1LTIxNDktNDUwMC04ZTE1LTZkZTU1YWM1MGRmMyIsInR5cCI6IkJlYXJlciIsImF6cCI6Im15Y2xpZW50Iiwic2Vzc2lvbl9zdGF0ZSI6ImRlM2Q4ZjZhLTE4YzAtNGYzYS1hNmQwLWNlNTBjNmM2ZmNjMyIsImFjciI6IjAiLCJyZWFsbV9hY2Nlc3MiOnsicm9sZXMiOlsiYWRtaW4iXX0sInNjb3BlIjoib3BlbmlkIGVtYWlsIHByb2ZpbGUiLCJzaWQiOiJkZTNkOGY2YS0xOGMwLTRmM2EtYTZkMC1jZTUwYzZjNmZjYzMiLCJlbWFpbF92ZXJpZmllZCI6ZmFsc2UsInByZWZlcnJlZF91c2VybmFtZSI6ImFkbWluIn0.sGblDdBIkwnDDUcGd7-2QlCeA17gnmuvXosqpZ0T_zGlKtr6Ta-z1QSgwdc8K5ivekyIQmcYAIh-eHmfVxjCLKZ6fR-AdTeqenXdkNJuMREzwKpnOFx1Wq2LZUb-hqWKJimBKi2iUPlu4ENAVbFOWxcMwIedySpN74RHF3yP4BKr4YfAmr5u9CSX3EYw0LMiMVlt6l_FKNssKnTLlBq0IPDlBdwV9D1l6qpDXu_uIbvUzb_w8rnSoUGMqqqxI-RNF6m5dit29KWinFfkat5-g-lvbiVz8l0wYfMBGb9ESwC0aXJARcEG7PdhtqYLPjsGFVrjqHMq1ci_BVivAt3Htw");
        System.out.println(verify);
        System.out.println(verify.getExpiresAt());
        System.out.println(verify.getClaim("scope"));
        System.out.println(verify.getExpiresAtAsInstant());
        System.out.println(verify.getClaims());
    }
}