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flutter中的共享依赖项无法正常工作。数据未持久化

bloc sharedpreferences dart flutter android
  •  0
  • Dinesh Kumar M  · 技术社区  · 2 年前

    我在这里提供了3个文件和我的main.dart文件。所以问题是,即使在我重新运行应用程序或重新启动应用程序时,我也希望将数据保存在HomePageScreen.dart上。

    这是我的主.dart()文件 

    import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/scheduler.dart';
import 'package:dinesh_s_application42/theme/theme_helper.dart';
import 'package:dinesh_s_application42/routes/app_routes.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/expense_bloc.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/income/income_bloc.dart';
import 'package:dinesh_s_application42/presentation/settings_screen/ProfileBloc.dart';
void main() async {
  
  WidgetsFlutterBinding.ensureInitialized();
  final prefs = await SharedPreferences.getInstance();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
  ]);

  ///Please update theme as per your need if required.
  ThemeHelper().changeTheme('primary');
  runApp(MyApp(prefs));
}
class MyApp extends StatelessWidget {
    final SharedPreferences prefs; // Declare the SharedPreferences instance

  MyApp(this.prefs); 
  @override
  Widget build(BuildContext context) {
    return MultiBlocProvider( // Use MultiBlocProvider to provide multiple blocs if needed
      providers: [
        BlocProvider<ExpenseBloc>(create: (context) => ExpenseBloc(prefs)), // Provide your ExpenseBloc
        BlocProvider<IncomeBloc>(create: (context) => IncomeBloc()),
        BlocProvider<ProfileBloc>(create: (context) => ProfileBloc()),
      ],
      child: MaterialApp(
      theme: theme,
      title: 'dinesh_s_application42',
      debugShowCheckedModeBanner: false,
      initialRoute: AppRoutes.startPageScreen,
      routes: AppRoutes.routes,)
    );
  }
}

    这是我的expense_bloc.dart文件 

    import 'package:bloc/bloc.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:convert';

import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/expense.dart';

class ExpenseBloc extends Bloc<ExpenseEvent, List<Expense>> {
  final SharedPreferences _prefs;

  ExpenseBloc(this._prefs) : super([]);

  @override
  Stream<List<Expense>> mapEventToState(ExpenseEvent event) async* {
    if (event is AddExpenseEvent) {
      final updatedExpenses = List.of(state)..add(event.expense);
      await saveExpenses(updatedExpenses);
      yield updatedExpenses;
    } else if (event is RemoveExpenseEvent) {
      final updatedExpenses = List.of(state)..remove(event.expense);
      await saveExpenses(updatedExpenses);
      yield updatedExpenses;
    } else if (event is LoadExpensesEvent) {
      yield event.expenses;
    }
  }

  Future<void> saveExpenses(List<Expense> expenses) async {
    final jsonData = expenses.map((expense) => expense.toJson()).toList();
    await _prefs.setString('expenses', jsonEncode(jsonData));
  }

  Future<void> loadExpenses() async {
    final jsonData = _prefs.getString('expenses');
    if (jsonData != null) {
      final List<dynamic> jsonList = jsonDecode(jsonData);
      final expenses = jsonList.map((jsonExpense) => Expense.fromJson(jsonExpense)).toList();
      add(LoadExpensesEvent(expenses));
    }
  }
}

abstract class ExpenseEvent {}

class AddExpenseEvent extends ExpenseEvent {
  final Expense expense;

  AddExpenseEvent(this.expense);
}

class RemoveExpenseEvent extends ExpenseEvent {
  final Expense expense;

  RemoveExpenseEvent(this.expense);
}

class LoadExpensesEvent extends ExpenseEvent {
  final List<Expense> expenses;

  LoadExpensesEvent(this.expenses);
}

    这是expense.dart文件 

    import 'package:uuid/uuid.dart';
import "package:flutter/material.dart";
import 'package:intl/intl.dart';

final formatter = DateFormat.yMd();

const uuid = Uuid();

enum Category { Essentials, Transportation, Housing, Healthcare, Education, Personal_Care, Entertainment, Communication, Savings, Investments, Dept_payments, Miscellaneous, Travel_Entertainment, Emergency_Fund}

const categoryIcons = {
  Category.Essentials: Icons.add_business_rounded,
  Category.Transportation: Icons.directions_car_filled,
  Category.Housing: Icons.add_home_work_sharp ,
  Category.Healthcare: Icons.health_and_safety_rounded,
  Category.Education: Icons.school_rounded,
  Category.Personal_Care: Icons.attribution_outlined,
  Category.Entertainment: Icons.add_home_work_sharp ,
  Category.Communication: Icons.face_retouching_natural_sharp,
  Category.Savings: Icons.area_chart_sharp,
  Category.Investments: Icons.attach_money_outlined,
  Category.Dept_payments: Icons.feed_rounded ,
  Category.Miscellaneous: Icons.fitness_center_sharp,
  Category.Travel_Entertainment: Icons.fire_truck_rounded ,
  Category.Emergency_Fund: Icons.fireplace_outlined,
};

class Expense {
  Expense({
    required this.title,
    required this.amount,
    required this.date,
    required this.category,
  }) : 
  
  
  id = uuid.v4();

  

  final String id;
  final String title;
  final double amount;
  final DateTime date;
  final Category category;

   Map<String, dynamic> toJson() {
    return {
      'title': title,
      'amount': amount,
      'date': date.toIso8601String(),
      'category': category.index
    };
  }

 
  factory Expense.fromJson(Map<String, dynamic> json) {
  return Expense(
    title: json['title'],
    amount: json['amount'],
    date: DateTime.parse(json['date']),
    category: Category.values[json['category']],
  );
}



  String get formattedDate {
    return formatter.format(date);
  }
}

class ExpenseBucket {
  const ExpenseBucket({
    required this.category,
    required this.expenses,
  });

  ExpenseBucket.forCategory(List<Expense> allExpenses, this.category)
      : expenses = allExpenses
            .where((expense) => expense.category == category)
            .toList();

  final Category category;
  final List<Expense> expenses;

  double get totalExpenses {
    double sum = 0;

    for (final expense in expenses) {
      sum = sum + expense.amount;
    }
    return sum;
  }
}

    这是我的HomePageScreen.dart文件: 

    import '../menubar_draweritem/menubar_draweritem.dart';
import 'package:dinesh_s_application42/core/app_export.dart';
import 'package:dinesh_s_application42/widgets/app_bar/appbar_image.dart';
import 'package:dinesh_s_application42/widgets/app_bar/appbar_image_1.dart';
import 'package:dinesh_s_application42/widgets/app_bar/custom_app_bar.dart';
import 'package:dinesh_s_application42/widgets/custom_elevated_button.dart';
import 'package:flutter/material.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/expense.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/new_expense.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/expense_bloc.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/income/income_bloc.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/income/incomes_list.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/expense/expenses_list.dart';

import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/income/income.dart';
import 'package:dinesh_s_application42/presentation/homepage_screen/functionality/income/new_income.dart';
import 'package:flutter_bloc/flutter_bloc.dart'; 


// ignore_for_file: must_be_immutable
class _ExpensesState extends State<HomepageScreen> {
  final List<Expense> _registeredExpenses = [    ];
  final List<Income> _registeredIncomes =   [    ];
  
  Map<String, double> _categoryExpenses = {
  "Essentials": 0.0,
  "Category2": 0.0, // Initialize for all 14 categories
  // ...
};

  double calculateTotalIncome() {
    final List<Income> incomes = context.watch<IncomeBloc>().state;
    double totalIncome = incomes.fold(0, (sum, income) => sum + income.amount);
    return totalIncome;
  }

  double calculateTotalExpense() {
    final List<Expense> expenses = context.watch<ExpenseBloc>().state;
    double totalExpense = expenses.fold(0, (sum, expense) => sum + expense.amount);
    return totalExpense;
  }

  double calculateTotalAmount() {
    double totalIncome = calculateTotalIncome();
    double totalExpense = calculateTotalExpense();
    double totalAmount = totalIncome - totalExpense;
    return totalAmount;
  }


  void _openAddExpenseOverlay() {
    showModalBottomSheet(
      context: context,
      builder: (ctx) => NewExpense(onAddExpense: _addExpense),
    );
  }

  void _addExpense(Expense expense) {
  setState(() {
    _registeredExpenses.add(expense);

    String categoryKey = expense.category.toString();

    _categoryExpenses[categoryKey] = (_categoryExpenses[categoryKey] ?? 0) + expense.amount;
  });
}


  void _openAddIncomeOverlay() {
    showModalBottomSheet(
      context: context,
      builder: (ctx) => NewIncome(onAddIncome: _addIncome),
    );
  }

  void _addIncome(Income income) {
    setState(() {
      _registeredIncomes.add(income);
    });
  }

  

  GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  Widget build(BuildContext context) {
    mediaQueryData = MediaQuery.of(context);
    

    return SafeArea(
        child: Scaffold(
            extendBody: true,
            extendBodyBehindAppBar: true,
            key: _scaffoldKey,
            drawer: MenubarDraweritem(),
            body: Container(
                width: mediaQueryData.size.width,
                height: mediaQueryData.size.height,
                decoration: BoxDecoration(
                    image: DecorationImage(
                        image: AssetImage(ImageConstant.imgHomepage),
                        fit: BoxFit.cover)),
                child: SizedBox(
                    width: double.maxFinite,
                    child: Column(
                        mainAxisAlignment: MainAxisAlignment.start,
                        children: [
                          Container(
                              padding: getPadding(top: 29, bottom: 29),
                              decoration: AppDecoration.fillGray.copyWith(
                                  borderRadius:
                                      BorderRadiusStyle.customBorderBL40),
                              child: Column(
                                  mainAxisSize: MainAxisSize.min,
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  mainAxisAlignment: MainAxisAlignment.center,
                                  children: [
                                    CustomAppBar(
                                        height: getVerticalSize(42),
                                        leadingWidth: getHorizontalSize(60),
                                        leading: AppbarImage(
                                            svgPath: ImageConstant.imgMenu,
                                            margin: getMargin(
                                                left: 20, top: 8, bottom: 9),
                                            onTap: () {
                                              navigatetomenu(context);
                                            }),
                                        actions: [
                                          AppbarImage1(
                                              svgPath:
                                                  ImageConstant.imgSettings,
                                              margin: getMargin(
                                                  left: 25, right: 25),
                                              onTap: () {
                                                navigatetosettings(context);
                                              })
                                        ]),
                                    SizedBox(height: getVerticalSize(15)),
                                    Align(
                                        alignment: Alignment.center,
                                        child: SizedBox(
                                            height: getVerticalSize(77),
                                            width: getHorizontalSize(300),
                                            child: Stack(
                                                alignment: Alignment.bottomLeft,
                                                children: [
                                                  Align(
                                            alignment: Alignment.bottomCenter,
                                            child: Padding(
                                            padding: getPadding(top: 10),
                                            child: Text("₹${calculateTotalAmount().toStringAsFixed(2)}",
                                                          style: CustomTextStyles
                                                              .displayMediumJost))),
                                                  Align(
                                            alignment: Alignment.topCenter,
                                            child: Padding(
                                                padding: getPadding(left: 1),
                                                child: Text("Total balance",
                                                              style: theme
                                                                  .textTheme
                                                                  .headlineSmall)))
                                                ]))),
                                    CustomElevatedButton(
                                        height: getVerticalSize(49),
                                        onTap: _openAddExpenseOverlay,
                                        text: "Click to add Expense",
                                        margin: getMargin(
                                            left: 40, top: 16, right: 73),
                                        leftIcon: Container(
                                            margin: getMargin(right: 29),
                                            child: CustomImageView(
                                                svgPath:
                                                    ImageConstant.imgPlus)),
                                        buttonStyle:
                                            CustomButtonStyles.outlineBlack,
                                        buttonTextStyle: CustomTextStyles
                                            .titleLargeJostOnPrimaryContainer),
                                    CustomElevatedButton(
                                        height: getVerticalSize(49),
                                        text: "Click to add Income",
                                        onTap: _openAddIncomeOverlay,
                                        margin: getMargin(
                                            left: 40,
                                            top: 40,
                                            right: 73,
                                            bottom: 4),
                                        leftIcon: Container(
                                            margin: getMargin(right: 21),
                                            child: CustomImageView(
                                                svgPath:
                                                    ImageConstant.imgPlus)),
                                        buttonStyle:
                                            CustomButtonStyles.outlineBlack,
                                        buttonTextStyle: CustomTextStyles
                                            .titleLargeJostOnPrimaryContainer)
                                  ])),
                          Padding(
                    padding: getPadding(top: 11, bottom: 11),
                    child: Text("Latest Transactions",
                        style: CustomTextStyles.headlineSmallSemiBold)),
                Padding(
                    padding: getPadding(top: 1, bottom: 1),
                    child: Text("Expenses",
                        style: CustomTextStyles.titleSmallInter)),
                BlocBuilder<ExpenseBloc, List<Expense>>(
                  builder: (context, expenses) {
                    Widget mainContent = const Center(
                      child: Text('No expenses found. Start adding Some!'),
                    );

                    if (expenses.isNotEmpty) {
                      mainContent = ExpensesList(
                        expenses: expenses,
                        onRemoveExpense: (expense) {
                          context
                              .read<ExpenseBloc>()
                              .add(RemoveExpenseEvent(expense));
                        },
                      );
                    }

                    return Expanded(
                      child: mainContent,
                    );
                    
                  },
                ),
                Padding(
                    padding: getPadding(top: 1, bottom: 1),
                    child: Text("Incomes",
                        style: CustomTextStyles.titleSmallInter)),
                
                BlocBuilder<IncomeBloc, List<Income>>(
                  builder: (context, incomes) {
                    Widget mainContent = const Center(
                      child: Text('No incomes found. Start adding Some!'),
                    );

                    if (incomes.isNotEmpty) {
                      mainContent = IncomesList(
                        incomes: incomes,
                        onRemoveIncome: (income) {
                          context
                              .read<IncomeBloc>()
                              .add(RemoveIncomeEvent(income));
                        },
                      );
                    }

                    return Expanded(
                      child: mainContent,
                    );
                  },
                ),
                        ])))));
  }

  /// Opens the drawer of the current scaffold using the [_scaffoldKey] instance
  /// variable.
  navigatetomenu(BuildContext context) {
    _scaffoldKey.currentState?.openDrawer();
  }

  navigatetosettings(BuildContext context) {
    Navigator.popAndPushNamed(context, AppRoutes.settingsScreen);
  }
}

class HomepageScreen extends StatefulWidget {
  const HomepageScreen({Key? key})
      : super(
          key: key,
        );
  @override
  State<HomepageScreen> createState() {
    return _ExpensesState();
  }
}

    所以我想在这个主页屏幕上显示支出项目的内容,它确实这样做了。但当我关闭应用程序并再次打开它时,所有数据都不见了。我使用过共享引用,但它似乎仍然不起作用。

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