从flutter中的日历中获取所选日期的值

import 'package:flutter/material.dart';

class MyDatePicker extends StatefulWidget {
  @override
  _MyDatePickerState createState() => _MyDatePickerState();
}

class _MyDatePickerState extends State<MyDatePicker> {
  DateTime selectedDate;

  Future<void> _selectDate(BuildContext context) async {
    final DateTime picked = await showDatePicker(
      context: context,
      initialDate: DateTime.now(),
      firstDate: DateTime(2010),
      lastDate: DateTime(2030),
    );
    if (picked != null && picked != selectedDate) {
      setState(() {
        selectedDate = picked;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Date Picker Example'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              onPressed: () => _selectDate(context),
              child: Text('Select Date'),
            ),
            SizedBox(height: 20),
            Text(
              'Selected Date: ${selectedDate != null ? selectedDate.toString() : "No date selected"}',
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyDatePicker(),
  ));
}