在Flutter格式化日期

Dart内置的方法，用于根据要求在Flutter格式化日期是非常有限和限制性的。在处理日期时，它应该采用人类可读的格式，但不幸的是，除非您使用第三方包，否则无法在flutter中格式化日期。

在本文中，我们将研究一种称为intl 包的此类包。

使用国际包：

将以下依赖项添加到您的pubspec.yaml文件中，您可以在此处找到最新的依赖项。

dependencies:
  intl: ^0.17.0

使用终端添加：

您还可以使用终端轻松获取最新的 intl 库：

flutter pub add intl

导入它：

现在在你的Dart代码中导入 intl 包：

import 'package:intl/intl.dart';

尽管如此，如果您在使用 intl 时遇到任何错误，只需使用以下命令：

flutter pub get

现在让我们看看下面的例子。

例子：

在下面的代码中，我们不会使用 intl 包进行格式化。另外，看看下面代码的输出。

Dart

import 'package:flutter/material.dart';
  
void main() {
  runApp(dateDemo());
}
  
class dateDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        
      // browser tab title
      title: "Geeksforgeeks",
        
      // Body
      home: Scaffold(   
          
          // AppBar
          appBar: AppBar(
              
            // AppBar color
            backgroundColor: Colors.green.shade900,
              
            // AppBar title
            title: Text("Geeksforgeeks"),           
          ),
          
          // Container or Wrapper
          body: Container(                         
            margin: EdgeInsets.fromLTRB(95, 80, 0, 0), 
              
            // printing text on screen
            child: Text(                           
                
              // Formatted Date
              // Builtin fomat / without formatting
              DateTime.now().toString(),         
              style: TextStyle(
                  
                  // Styling text
                  fontWeight: FontWeight.bold, fontSize: 30), 
            ),
          )),
    );
  }
}

输出：

Dart内置格式

现在让我们使用 intl 包来格式化日期。

Dart

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
  
void main() {
  runApp(dateDemo());
}
  
class dateDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        
      // browser tab title
      title: "Geeksforgeeks",   
        
      // Body
      home: Scaffold(  
            
          // AppBar
          appBar: AppBar(
               
            // AppBar color
            backgroundColor: Colors.green.shade900,
              
            // AppBar title
            title: Text("Geeksforgeeks"),           
          ),
          
          // Container or Wrapper
          body: Container(                         
            margin: EdgeInsets.fromLTRB(95, 80, 0, 0), 
              
            // printing text on screen
            child: Text( 
                
              // Formatted Date
              DateFormat.yMMMEd()   
                
              // displaying formatted date
              .format(DateTime.now()),       
              style: TextStyle(
                  
                // Styling text
                fontWeight: FontWeight.bold, fontSize: 30), 
            ),
          )),
    );
  }
}

输出：

格式化日期

更多 DateFormat 函数：

intl 中的 DateFormat 类提供了许多函数来相应地格式化日期，如下所示：

Use	Description	Example
DateFormat.yMMMEd().format(date)	Day Name ,Month Name ,Date,Year	Fri, Sep 3, 2021
DateFormat.MEd().format(date)	Day Name,Month/Date in Numbers	Fri , 9/3
DateFormat.MMMMEEEEd().format(date))	DayName,MonthName Date	Friday ,September 3
DateFormat.yMMMMEEEEd().format(date))	DayName ,MonthName Date,Year	Friday ,September 3,2021
DateFormat.EEEE().format(date)	Full DayName only	Friday
DateFormat.E().format(date)	Short DayName	Fri
DateFormat.M().format(date)	Month-Number	9
DateFormat.MMM().format(date)	Short MonthName	Sep
DateFormat.LLLL().format(date)	Full MonthName	September
DateFormat.j().format(date)	Current Time only	4 PM

例子：

Dart

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
  
void main() {
  runApp(dateDemo());
}
  
class dateDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Date-Demo",
      home: Scaffold(
          appBar: AppBar(
              
            // AppBar
            backgroundColor: Colors.green.shade900,
              
            // AppBar title
            title: Text("Geeksforgeeks"), 
          ),
          body: Container(  
              
            // Container/Wrapper
            width: double.infinity,
            child:
                Column(  
                    
                  // use Column for more Text()
                  mainAxisAlignment: MainAxisAlignment.center,
             children: [
              Text(
                  
                // Day,Month Date,Year
                DateFormat.yMMMEd().format(DateTime.now()),  
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                 // Day,Month/Date in Numbers
                DateFormat.MEd().format(DateTime.now()),   
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // DayName,MonthName Date
                DateFormat.MMMMEEEEd().format(DateTime.now()), 
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // DayName,MonthName Date,Year
                DateFormat.yMMMMEEEEd().format(DateTime.now()),
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                 // Full DayName only
                DateFormat.EEEE().format(DateTime.now()),    
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // Short DayName
                DateFormat.E().format(DateTime.now()),        
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                 // Month-Number
                DateFormat.M().format(DateTime.now()),       
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // short MonthName
                DateFormat.MMM().format(DateTime.now()),     
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // full MonthName
                DateFormat.LLLL().format(DateTime.now()),     
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
              Text(
                  
                // Current Time only
                DateFormat.j().format(DateTime.now()),       
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 20),
              ),
            ]),
          )),
    );
  }
}

输出：

更多 DateFormat 函数

intl是一个具有很多功能的库，所以不要在这里结束并从他们的文档中探索更多。

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