First, the method is detailed.

• Naming constructs to get the current time
  

  now()

• DateTime timestamp
  

  millisecondsSinceEpoch

• Timestamp Transfer DateTime
  

  fromMillisecondsSinceEpoch

• String Rotation DateTime
  

  parse(string)

• Time comparison - before
  

  isBefore(date)

• Time comparison - after
  

  isAfter(date)

• Time comparison - equality
  

  isAtSameMomentAs(date)

• Greater than return 1; equal to return 0; less than Return-1
  

  compareTo(date)

• Time increases
  

  add(Duration)

• Time reduction
  

  subtract(Duration)

• Hours of difference between two times
  

  difference(date)

• Simplified local time zone code
  

  timeZoneName

• Return UTC and Hours of Local Time Difference
  

  timeZoneOffset

• Return years, months, days, hours, minutes, seconds, milliseconds, subtleties
  

  year,month,day,hour,minute,second,millisecond,microsecond

• Return to Wednesday
  

  weekday

2. Conversion between strings and dates

• String-->DateTime:
  

  DateTime.parse(String)；

• DateTime -->formatString:
  

  formatDate(DateTime ,[yyyy,'-',mm,'-',dd]);

Three, code examples

var today = DateTime.now();
print('The current time is: $today');

var date1 = today.millisecondsSinceEpoch;
print('Current timestamp: $date1');

var date2 = DateTime.fromMillisecondsSinceEpoch(date1);
print('Time stamp date: $date2');

//Stitching date
var dentistAppointment = new DateTime(2019, 6, 20, 17, 30,20);
print(dentistAppointment);

// String Conversion date
DateTime date3 = DateTime.parse("2019-06-20 15:32:41");
print(date3);

// Time comparison
print(today.isBefore(date3));// Before
print(today.isAfter(date3)); // After that
print(date3.isAtSameMomentAs(date3));// identical

print(date3.compareTo(today));// Greater than return 1; equal to return 0; less than return-1. 
// print(DateTime.now().toString());
// print(DateTime.now().toIso8601String());

//Time increases
var fiftyDaysFromNow = today.add(new Duration(days: 5));
print('today Add 5 days: $fiftyDaysFromNow');

//Time reduction
DateTime fiftyDaysAgo = today.subtract(new Duration(days: 5));
print('today Less 5 days: $fiftyDaysAgo');

//Hours of difference between two times
print('Compare two hours of time difference: ${fiftyDaysFromNow.difference(fiftyDaysAgo)}');

print('Simplified code for local time zone: ${today.timeZoneName}');

print('Return UTC Hours with local time difference: ${today.timeZoneOffset}');

print('Acquisition year, month and day: ${today.year}');//month,day,hour,minute,second,millisecond,microsecond

print('Weekly: ${today.weekday}');// Return to Wednesday

Fourth, example results