26Flutter 日期 和时间戳/格式化日期库/flutter异步/ 官方自带日期组件showDatePicker、时间组件showTimePicker以及国际化

/*

一、Flutter日期和时间戳

日期转换成时间戳

var now=newDateTime.now();

print(now.millisecondsSinceEpoch); //单位毫秒，13位时间戳。

时间戳转换成日期：

var now=new DateTime.now();

var a=now.millisecondsSinceEpoch;//时间戳

print(DateTime.fromMillisecondsSinceEpoch(a));

二、Flutter第三方库date_format的使用：

https://pub.dev/packages/date_format

三、调用flutter自带日期组件和时间组：

*/

pubspec.yaml

  flutter_localizations:
    sdk: flutter

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_demo/pages/Search.dart';
import 'routes/Routes.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
 
void main() {
  runApp(MyApp());
}
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
        localizationsDelegates: [
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate
        ],
        supportedLocales: [
          const Locale('zh','CH'),
          const Locale('en','US')
        ],
        debugShowCheckedModeBanner: false, //去掉debug图标：
        initialRoute: '/',
        onGenerateRoute: onGenerateRoute);
  }
}

DatePicker.dart

import 'package:flutter/material.dart';
import 'package:date_format/date_format.dart';
 
class DatePickerDemo extends StatefulWidget {
  DatePickerDemo({Key key}) : super(key: key);
  _DatePickerDemoState createState() => _DatePickerDemoState();
}
 
class _DatePickerDemoState extends State<DatePickerDemo> {
  var now = DateTime.now();
  DateTime _nowDate = DateTime.now();
  var _nowTime=TimeOfDay(hour: ,minute: );
  // String time;
  _showDatePicker() async {
    // showDatePicker(
    //   context: context,
    //   initialDate: _nowDate,
    //   firstDate: DateTime(1980),
    //   lastDate: DateTime(2100)
    // ).then((result){
    //   print(result);
    // });
 
    var result = await showDatePicker(
        context: context,
        initialDate: _nowDate,
        firstDate: DateTime(),
        lastDate: DateTime(),
        locale: Locale('zh')
    );
 
    print(result);
    setState(() {
      this._nowDate = result;
    });
  }
 
  _showTimePicker() async{
    var result=await showTimePicker(
      context: context,
      initialTime:_nowTime
    );
    setState(() {
      this._nowTime=result;
    });
  }
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    // print(778899);
    // //
    // print(now.millisecondsSinceEpoch); //1568786998995
    // print(DateTime.fromMillisecondsSinceEpoch(1568786998995)); //2019-09-18 14:09:58.995
 
    // print(formatDate(DateTime.now(),[yyyy,'年',mm,'月',dd]));
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('DatePicker')),
        body: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Row(
              children: <Widget>[
                InkWell(
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text("${formatDate(_nowDate, [
                        yyyy,
                        '年',
                        mm,
                        '月',
                        dd,
                        '日'
                      ])}"),
                      Icon(Icons.arrow_drop_down)
                    ],
                  ),
                  onTap: _showDatePicker,
                ),
                InkWell(
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text("${_nowTime.format(context)}"),
                      Icon(Icons.arrow_drop_down)
                    ],
                  ),
                  onTap: _showTimePicker,
                )
              ],
            )
          ],
        ));
  }
}