在某些参考资料中是说这两个方法任选其一就可，但经我测试，必须两个方法同时使用，才不会再出现错误提示

PHP Warning: strtotime(): It is not safe to rely on the system’s timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this