如何保存添加后的颤振表日历事件

Question

我是flutter编程的新手，我按照本教程设置了表日历，以允许用户添加自己的事件。然而，当我转到应用程序的另一个页面或重新启动应用程序时，日历上的事件不会保存。有人知道如何确保事件不会消失吗?谢谢你！

代码:

class CalendarRoute extends StatefulWidget{
@override
_CalendarRouteState createState() => _CalendarRouteState();
}
 class _CalendarRouteState extends State<CalendarRoute> {
 CalendarFormat format = CalendarFormat.month;
 DateTime selectedDay = date;
 DateTime focusedDay = date;
 late Map <DateTime,List<Event>> selectedEvents;
 TextEditingController _eventController = TextEditingController();
 @override
 void initState(){
   selectedEvents = {};
   super.initState();
 }
 List<Event> _getEventsFromDay(DateTime date){
   return selectedEvents[date]??[];
 }
 void dispose(){
  _eventController.dispose();
 super.dispose();
 }
 @override
 Widget build(BuildContext context) {
   return Scaffold(
     appBar: AppBar(
     title: Text("Calendar",
     style: TextStyle(color: Colors.yellow)),
     backgroundColor: Colors.brown,
  ),
  body:
      Column(
   children:[
  TableCalendar(
    firstDay: DateTime.utc(2021,6,8),
    lastDay: DateTime.utc(2022,6,8),
    focusedDay: focusedDay,
    calendarFormat: format,
    onFormatChanged: (CalendarFormat _format){
      setState((){
        format = _format;
      });
      },
    startingDayOfWeek: StartingDayOfWeek.monday,
    onDaySelected: (DateTime selectDay, DateTime focusDay){
      setState((){
        selectedDay = selectDay;
        focusedDay = focusDay;
      });
    },
      selectedDayPredicate: (DateTime day){
        return isSameDay(selectedDay, day);
      },
      eventLoader:_getEventsFromDay,
    calendarStyle: CalendarStyle(
      isTodayHighlighted: true,
          selectedDecoration: BoxDecoration(
              color: Colors.yellow,
            shape: BoxShape.rectangle,
          ),
      selectedTextStyle: TextStyle(color: Colors.black),
      todayDecoration: BoxDecoration(
        color: Colors.brown,
        shape: BoxShape.rectangle,
      )
  ),
    headerStyle:HeaderStyle(
      formatButtonVisible: true,
      titleCentered: true,
      formatButtonShowsNext: false,
      formatButtonDecoration: BoxDecoration(
        color: Colors.brown,
      ),
        formatButtonTextStyle: TextStyle(color: Colors.yellow)
    )
  ),
  ..._getEventsFromDay(selectedDay).map((Event event)=> ListTile(title:Text(event.title))),
]),
  floatingActionButton: FloatingActionButton.extended(
    onPressed: ()=>showDialog(context:context, builder: (context)=>AlertDialog(
      title: Text("Add event"),
      content: TextFormField(
        controller:_eventController,
      ),
      actions: [TextButton(
        child: Text("Cancel"),
        onPressed:() =>Navigator.pop(context),
      ),
        TextButton(
          child: Text("Ok"),
          onPressed:() {
            if(_eventController.text.isEmpty){
            }
            else if (selectedEvents[selectedDay]!=null){
              selectedEvents[selectedDay]!.add(
                Event(title: _eventController.text),);
            }
            else{
              selectedEvents[selectedDay] = [Event(
              title: _eventController.text
              )
              ];
            }
            _eventController.clear();
            Navigator.pop(context);
            setState((){});
            return;
          }
        ),]
    )),
  label: Text("Add event"),
  icon: Icon(Icons.add),
  ),

Answer 1

您需要使用shared_preferences

链接到pub包

更多信息在这里在Flutter.dev