public class JwtUtils {
    /**过期时间*/
    public static final long EXPIRE = 1000 * 60 * 60 * 24;
    /**密钥*/
    public static final String APP_SECRET = "zjKkye4PN59B2wriTjtVCo3BOYoD1B";
    /**根据id和昵称获取token*/
    public static String getJwtToken(String id, String nickname){
        String JwtToken = Jwts.builder()
                .setHeaderParam("typ", "JWT")
                .setHeaderParam("alg", "HS256")
                .setSubject("ll-user")  // 主题
                .setIssuedAt(new Date()) // 签发时间
                .setExpiration(new Date(System.currentTimeMillis() + EXPIRE))
                .claim("id", id)
                .claim("nickname", nickname)
                .signWith(SignatureAlgorithm.HS256, APP_SECRET)// 签名算法以及密匙
                .compact();
        return JwtToken;
    }

    /**
     * 判断token是否存在与有效
     * @param jwtToken
     * @return
     */
    public static boolean checkToken(String jwtToken) {
        if(StringUtils.isEmpty(jwtToken)) return false;
        try {
            Jwts.parser().setSigningKey(APP_SECRET).parseClaimsJws(jwtToken);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    /**
     * 判断token是否存在与有效
     */
    public static boolean checkToken(HttpServletRequest request) {
        String jwtToken = request.getHeader("token");
        return checkToken(jwtToken);
    }

    /**
     * 根据token获取id
     */
    public static String getUserIdByJwtToken(HttpServletRequest request) {
        String jwtToken = request.getHeader("token");
        if(StringUtils.isEmpty(jwtToken)) return "";
        Jws<Claims> claimsJws = Jwts.parser().setSigningKey(APP_SECRET).parseClaimsJws(jwtToken);
        Claims claims = claimsJws.getBody();
        return (String)claims.get("id");
    }
}