Dart-Flutter DateTime日期轉換

1.日期轉換成時間戳

var now=new DateTime.now();

print(now.millisecondsSinceEpoch); //單位毫秒，13位時間戳

2.時間戳轉換成日期

var now=new DateTime.now();

var a=now.millisecondsSinceEpoch; // 時間戳

print(DateTime.fromMillisecondsSinceEpoch(a));

3.創建指定時間 

DateTime assignDay = new DateTime(2020,10,10);

print(assignDay);   // 2020-10-10 00:00:00.000

4.計算時間跨度

// 例如計算1天14小時45分的跨度

Duration timeRemaining = new Duration(days:1, hours:14, minutes:45);

print(timeRemaining);  // 38:45:00.000000

5.字符串轉DateTime

DateTime.parse('2019-11-08') 或者 DateTime.parse('2019-11-08 12:30:05')

6.在之前——時間比較

var today = DateTime.now();

var date = DateTime.parse("2019-06-20 15:32:41");

today.isBefore(date);

7.在之後——時間比較

var today = DateTime.now();

var date = DateTime.parse("2019-06-20 15:32:41");

today.isAfter(date);

8.相等——時間比較

var today = DateTime.now();

var date = DateTime.parse("2019-06-20 15:32:41");

today.isAtSameMomentAs(date);

9.時間增加

var today = DateTime.now();   // 2019-11-08 02:54:53.218443

var fiftyDaysFromNow = today.add(new Duration(days: 5));

print('today加5天：$fiftyDaysFromNow');  // today加5天：2019-11-13 02:54:53.218443

10.時間減少

var today = DateTime.now();   // 2019-11-08 02:54:53.218443

var fiftyDaysAgo = today.add(new Duration(days: 5));

print('today加5天：$fiftyDaysAgo ');  // today減5天：2019-11-03 02:54:53.218443

11.時間差(小時數)

var day1 = new DateTime(2019, 6, 20, 17, 30, 20);

var day2 = new DateTime(2019, 7, 21, 0,  0, 0);

print('比較兩個時間 差 小時數：${day1.difference(day2)}');  //  比較兩個時間 差 小時數：-726:29:40.000000

12.獲取年、月、日、星期、時、分、秒、毫秒、微妙

year、month、day、weekday、hour、minute、second、millisecond、microsecond

var today = DateTime.now();

print(today.year);

13.獲取本地時區簡碼

DateTime today = DateTime.now();

print('本地時區簡碼：${today.timeZoneName}');  //  本地時區簡碼：GMT

14.返回UTC與本地時差(小時數）

DateTime today = DateTime.now();

print('返回UTC與本地時差 小時數：${today.timeZoneOffset}');