Dart 日期時間 DateTime

一、獲取當前時間

var now = new DateTime.now();
print(now); // 2019-06-20 16:59:05.560543

二、設置時間

var d =new DateTime(2019, 6, 20, 16, 37 , 26);
print(d); // 2019-06-20 16:37:26.000

三、建立時間UTC

var ds = new DateTime.utc(2019, 10, 10, 9, 30);
print(ds); // 2019-10-10 09:30:00.000Z

四、解析時間

var d1 = DateTime.parse('2018-10-10 09:30:36');
print(d1); // 2018-10-10 09:30:36.000
var d2 = DateTime.parse('2018-10-10 09:30:30+0800');
print(d2); // 2018-10-10 01:30:30.000Z

五、時間加減

print(now.add(new Duration(minutes: 10)));//加10分鐘  2019-06-20 17:09:05.560543
print(now.add(new Duration(minutes: -10)));//減10分鐘 2019-06-20 16:49:05.560543

print(now.add(new Duration(hours: 2)));//加2小時 2019-06-20 18:59:05.560543
print(now.add(new Duration(hours: -2)));//減2小時 2019-06-20 14:59:05.560543

六、比較時間

var d3 = new DateTime(2019, 6, 20);
var d4 = new DateTime(2019, 7, 20);
var d5 = new DateTime(2019, 6, 20);

print(d3.isAfter(d4));//是否在d4以後 false
print(d3.isBefore(d4));//是否在d4以前 true 
print(d3.isAtSameMomentAs(d5));//是否相同 true

七、計算時間差

var d6 = new DateTime(2019, 6, 19, 16 , 30);
var d7 = new DateTime(2019, 6, 20, 15, 20);
var difference = d7.difference(d6);
print([difference.inDays, difference.inHours,difference.inMinutes]);//d6與d7相差的天數與小時,分鐘 [0, 22, 1370]

八、時間戳

print(now.millisecondsSinceEpoch);//單位毫秒，13位時間戳  1561021145560
print(now.microsecondsSinceEpoch);//單位微秒，16位時間戳  1561021145560543

九、打印當前時間

// padLeft(int width,String sring)：若是字符串長度小於width，在左邊填充sring
print("${now.year.toString()}-${now.month.toString().padLeft(2,'0')}-${now.day.toString().padLeft(2,'0')} ${now.hour.toString().padLeft(2, '0')}:${now.minute.toString().padLeft(2, '0')}:${now.second.toString().padLeft(2, '0')}");
// 2019-06-20 16:59:05