另一种方法，使用intl包。

创建DateTime的扩展:

date_time_extension.dart

import 'package:intl/date_symbol_data_local.dart';
import 'package:intl/intl.dart';

extension DateTimeExtension on DateTime {
  String format([String pattern = 'dd/MM/yyyy', String? locale]) {
    if (locale != null && locale.isNotEmpty) {
      initializeDateFormatting(locale);
    }
    return DateFormat(pattern, locale).format(this);
  }
}

导入你要使用DateTime类型的文件，你可以这样使用它:

DateTime.now().format();

DateTime.now().format('MM/yyyy');

DateTime.now().format('MM/yyyy', 'es');

main() {
  final String pattern = 'yyyy-MM-dd';
  final String formatted = DateFormat(pattern).format(DateTime.now());
  print(formatted);
}

更改yyyy-MM-dd字符串可以更改日期格式。我用这个模式字符串做了一个应用程序。

你可以在我的应用程序中实验字符串格式。 https://biplobsd.github.io/EpochConverterApp

在这里你可以看到我如何编辑模式和这个效果显示在顶部

这就给你提供了社交网络中的日期:[“今天”，“昨天”，“星期的哪一天”，等等。]

void main() {
      DateTime now = new DateTime(2018,6,26);
      print(date(now));
    }
    
    String date(DateTime tm) {
      DateTime today = new DateTime.now();
      Duration oneDay = new Duration(days: 1);
      Duration twoDay = new Duration(days: 2);
      Duration oneWeek = new Duration(days: 7);
      String month;
      switch (tm.month) {
        case 1:
          month = "january";
          break;
        case 2:
          month = "february";
          break;
        case 3:
          month = "march";
          break;
        case 4:
          month = "april";
          break;
        case 5:
          month = "may";
          break;
        case 6:
          month = "june";
          break;
        case 7:
          month = "july";
          break;
        case 8:
          month = "august";
          break;
        case 9:
          month = "september";
          break;
        case 10:
          month = "october";
          break;
        case 11:
          month = "november";
          break;
        case 12:
          month = "december";
          break;
      }
    
      Duration difference = today.difference(tm);
    
      if (difference.compareTo(oneDay) < 1) {
        return "today";
      } else if (difference.compareTo(twoDay) < 1) {
        return "yesterday";
      } else if (difference.compareTo(oneWeek) < 1) {
        switch (tm.weekday) {
          case 1:
            return "monday";
          case 2:
            return "tuesday";
          case 3:
            return "wednesday";
          case 4:
            return "thursday";
          case 5:
            return "friday";
          case 6:
            return "saturday";
          case 7:
            return "sunday";
        }
      } else if (tm.year == today.year) {
        return '${tm.day} $month';
      } else {
        return '${tm.day} $month ${tm.year}';
      }
    }

pubspec.yaml:

dependencies:
  intl:

main.dart:

import 'package:intl/intl.dart'; // for date format
import 'package:intl/date_symbol_data_local.dart'; // for other locales

void main() {
  var now = DateTime.now();
  print(DateFormat().format(now)); // This will return date using the default locale
  print(DateFormat('yyyy-MM-dd hh:mm:ss').format(now));
  print(DateFormat.yMMMMd().format(now)); // print long date 
  print(DateFormat.yMd().format(now)); // print short date 
  print(DateFormat.jms().format(now)); // print time 

  initializeDateFormatting('es'); // This will initialize Spanish locale
  print(DateFormat.yMMMMd('es').format(now)); // print long date in Spanish format
  print(DateFormat.yMd('es').format(now)); // print short date in Spanish format
  print(DateFormat.jms('es').format(now)); // print time in Spanish format
}

结果:

May 31, 2020 5:41:42 PM
2020-05-31 05:41:42
May 31, 2020
5/31/2020
5:41:42 PM
31 de mayo de 2020
31/5/2020
17:41:42

无依赖项方法[用于将日期显示为格式化字符串]

如果你想要以日/月/年的形式显示你的DateTime值或任何你喜欢的格式，字符串插值可以很方便:

"${_date.day} / ${_date.month} / ${_date.year}"

示例输出:

It's 23 out of 4 out of 1920

我不想使用任何额外的库，所以我走了这条路。

这也会起作用:

DateTime today = new DateTime.now();
String dateSlug ="${today.year.toString()}-${today.month.toString().padLeft(2,'0')}-${today.day.toString().padLeft(2,'0')}";
print(dateSlug);