Java8 优雅的判断对象是否为空

项目中经常遇到对象判空，如果是对象成员变量逐层判断， 会写很多if else 的逻辑语句

    public String testSimple(Context c) {
        if (c == null) {
            return "";
        }
        if (c.getUser() == null) {
            return "";
        }
        if (c.getUser().getCity() == null) {
            return "";
        }
        if (c.getUser().getCity().getInfo() == null) {
            return "";
        }
        return c.getUser().getCity() .getInfo();
    }

获取对象中某个成员变量

    public String testOptional(Context c) {
        return Optional.ofNullable(c).flatMap(c::getUser())
                .flatMap(user::getCity())
                .map(city::getInfo)
                .orElse("");
    }

UserDto userDto = userClientService.selectUser(userId);
            Long orgId = Optional.ofNullable(userDto).map(item -> item.getOrgId()).orElse(0L);
            if (orgId > 0) {
                //对象不为空，业务逻辑
            } else {
                LOGGER.error(null, "无法获取用户的组织机构Id,userId:{},key:{}", userId, ossKey);
            }