code: public static boolean needHttpDns() {
          try {
              TimeZone zone = TimeZone.getDefault();
              String id = zone.getID();
              return ("Asia/Shanghai".equals(id) || "Asia/Chongqing".equals(id) ||
                      "Asia/Harbin".equals(id) || "Asia/Urumqi".equals(id));
  
          } catch (Exception e) {
              return false;
          }
      }
docs: 简单通过时区判断是否在大陆