/*

采用JWT的生成TOKEN，及APP登录Token的生成和解析

 */

public class JwtTokenUtil {

    /**

     * token秘钥

     */

    public static final String SECRET = "1234567890";

    private static final String key = "user_code";

    /**

     * JWT生成Token.

     * JWT构成: header, payload, signature

     * @param userNo 登录成功后用户no, 参数no不可传空

     */

    @Validated

    public static String createToken(@NotBlank String userNo) throws Exception {

        Date iatDate = new Date();

        // expire time

        Calendar nowTime = Calendar.getInstance();

        nowTime.add(Calendar.DATE, 10);

        Date expiresDate = nowTime.getTime();

        // header Map

        Map<String, Object> map = new HashMap<>();

        map.put("alg", "HS256");

        map.put("typ", "JWT");

        // build token

        // param backups {iss:Service, aud:APP}

        String token = JWT.create().withHeader(map) // header

                .withClaim("iss", "Service") // payload

                .withClaim("aud", "APP")

                .withClaim(key, userNo)

                .withIssuedAt(iatDate) // sign time

                .withExpiresAt(expiresDate) // expire time

                .sign(Algorithm.HMAC256(SECRET)); // signature

        return token;

    }

    /**

     * 解密Token

     * @param token

     * @return

     * @throws Exception

     */

    private static Map<String, Claim> verifyToken(String token) {

        DecodedJWT jwt = null;

        try {

            JWTVerifier verifier = JWT.require(Algorithm.HMAC256(SECRET)).build();

            jwt = verifier.verify(token);

        } catch (Exception e) {

            // e.printStackTrace();

            // token 校验失败, 抛出Token验证非法异常

            throw new BusinessException("token 验证失败");

        }

        return jwt.getClaims();

    }

    /**

     * 根据Token获取user_no

     * @param token

     * @return user_No

     */

    public static String getAppUID(String token) {

        Map<String, Claim> claims = verifyToken(token);

        Claim user_id_claim = claims.get(key);

        if (null == user_id_claim || StringUtils.isBlank(user_id_claim.asString())) {

            // token 校验失败, 抛出Token验证非法异常

            throw new BusinessException("token 异常");

        }

        return user_id_claim.asString();

    }

}