//從header中得到token
        String authHeader = request.getHeader(JwtConstants.AUTHORIZATION);
        if (authHeader == null) {
            throw new ServletException("Missing or invalid X-AUTH-TOKEN header.");
        }
        // 驗證token
        Claims claims = null;
        try {
            claims 
 
= Jwts.parser().setSigningKey(JwtConstants.JWT_SECRET).parseClaimsJws(authHeader).getBody();
        } catch (final MalformedJwtException e){
            throw new ServletException("token 長度或者格式錯誤.");
        } catch (final SignatureException e) {
            throw new ServletException("Invalid token.");
        }
 

 Java: Meaning of catch (final SomeException e)?