在flutter应用程序中添加日期选择器的正确方法是什么？

在我的应用中，我正在创建注册页面，我需要在其中添加DOB。我想在其中添加日期选择器，但我没有获得正确的方法来执行此操作。

一个简单的应用程序，展示其用法：

import 'dart:async';

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  DateTime selectedDate = DateTime.now();

  Future<void> _selectDate(BuildContext context) async {
    final DateTime picked = await showDatePicker(
        context: context,
        initialDate: selectedDate,
        firstDate: DateTime(2015, 8),
        lastDate: DateTime(2101));
    if (picked != null && picked != selectedDate)
      setState(() {
        selectedDate = picked;
      });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            Text("${selectedDate.toLocal()}".split(' ')[0]),
            SizedBox(height: 20.0,),
            RaisedButton(
              onPressed: () => _selectDate(context),
              child: Text('Select date'),
            ),
          ],
        ),
      ),
    );
  }
}

还有一个Dartpad：

https://dartpad.dev/e5a99a851ae747e517b75ac221b73529

Flutter提供showDatePicker了实现此目的的功能。它是Flutter材料库的一部分。

您可以在showDatePicker找到完整的文档。

您还可以在此处找到实现的示例：日期和时间选择器

对于时间选择器-

在课程级别声明此变量

TimeOfDay selectedTime =TimeOfDay.now();

并调用此方法：

Future<Null> _selectTime(BuildContext context) async {
    final TimeOfDay picked_s = await showTimePicker(
        context: context,
        initialTime: selectedTime, builder: (BuildContext context, Widget child) {
           return MediaQuery(
             data: MediaQuery.of(context).copyWith(alwaysUse24HourFormat: false),
            child: child,
          );});

    if (picked_s != null && picked_s != selectedTime )
      setState(() {
        selectedTime = picked_s;
      });
  }

简单的方法是使用CupertinoDatePicker类：

首先导入其构建的软件包：

import 'package:flutter/cupertino.dart';

然后只需在您的表单中添加此小部件即可：

            Container(
              height: 200,
              child: CupertinoDatePicker(
                mode: CupertinoDatePickerMode.date,
                initialDateTime: DateTime(1969, 1, 1),
                onDateTimeChanged: (DateTime newDateTime) {
                  // Do something
                },
              ),
            ),

结果将如下图所示：

您也可以将模式更改为（dateAndTime，time）...例如，对于dateAndTime模式：

            Container(
              height: 200,
              child: CupertinoDatePicker(
                mode: CupertinoDatePickerMode.dateAndTime,
                initialDateTime: DateTime(1969, 1, 1, 11, 33),
                onDateTimeChanged: (DateTime newDateTime) {
                  //Do Some thing
                },
                use24hFormat: false,
                minuteInterval: 1,
              ),
            ),

结果将如下图所示：

首先，您需要创建一个变量。在该变量中，您可以按以下方式存储所选日期：

import 'package:flutter/material.dart';
import 'package:intl/intl.dart'; //this is an external package for formatting date and time

class DatePicker extends StatefulWidget {
  @override
  _DatePickerState createState() => _DatePickerState();
}

class _DatePickerState extends State<DatePicker> {
  DateTime _selectedDate;

  //Method for showing the date picker
  void _pickDateDialog() {
    showDatePicker(
            context: context,
            initialDate: DateTime.now(),
            //which date will display when user open the picker
            firstDate: DateTime(1950),
            //what will be the previous supported year in picker
            lastDate: DateTime
                .now()) //what will be the up to supported date in picker
        .then((pickedDate) {
      //then usually do the future job
      if (pickedDate == null) {
        //if user tap cancel then this function will stop
        return;
      }
      setState(() {
        //for rebuilding the ui
        _selectedDate = pickedDate;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        RaisedButton(child: Text('Add Date'), onPressed: _pickDateDialog),
        SizedBox(height: 20),
        Text(_selectedDate == null //ternary expression to check if date is null
            ? 'No date chosen!'
            : 'Picked Date: ${DateFormat.yMMMd().format(_selectedDate)}'),
      ],
    );
  }
}

这也是一个非常好的方法：

  import 'package:flutter/material.dart';
  import 'dart:async';

  void main() => runApp(new MyApp());

  class MyApp extends StatelessWidget {
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return new MaterialApp(
        title: 'Flutter Demo',
        theme: new ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: new MyHomePage(title: 'Flutter Date Picker Example'),
      );
    }
  }

  class MyHomePage extends StatefulWidget {
    MyHomePage({Key key, this.title}) : super(key: key);
    final String title;
    @override
    _MyHomePageState createState() => new _MyHomePageState();
  }

  class _MyHomePageState extends State<MyHomePage> {
    var finaldate;

    void callDatePicker() async {
      var order = await getDate();
      setState(() {
        finaldate = order;
      });
    }

    Future<DateTime> getDate() {
      // Imagine that this function is
      // more complex and slow.
      return showDatePicker(
        context: context,
        initialDate: DateTime.now(),
        firstDate: DateTime(2018),
        lastDate: DateTime(2030),
        builder: (BuildContext context, Widget child) {
          return Theme(
            data: ThemeData.light(),
            child: child,
          );
        },
      );
    }

    @override
    Widget build(BuildContext context) {
      return new Scaffold(
        appBar: new AppBar(
          title: new Text(widget.title),
        ),
        body: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Container(
                decoration: BoxDecoration(color: Colors.grey[200]),
                padding: EdgeInsets.symmetric(horizontal: 30.0),
                child: finaldate == null
                    ? Text(
                        "Use below button to Select a Date",
                        textScaleFactor: 2.0,
                      )
                    : Text(
                        "$finaldate",
                        textScaleFactor: 2.0,
                      ),
              ),
              new RaisedButton(
                onPressed: callDatePicker,
                color: Colors.blueAccent,
                child:
                    new Text('Click here', style: TextStyle(color: Colors.white)),
              ),
            ],
          ),
        ),
      );
    }
  }

这来自https://fluttercentral.com/Articles/Post/1199/Flutter_DatePicker_Example