使用Optional来避免空指针

    /**
     * 避免空指针问题
     * @param resolver
     * @param 
     * @return
     */
    public static  Optional resolve(Supplier resolver) {
        try {
            T result = resolver.get();
            return Optional.ofNullable(result);
        } catch (NullPointerException e) {
            return Optional.empty();
        }
    }