Flutter/Dart get_It单例定位器方法失败

Question

我有一个简单的dart类，如下所示：

import 'package:flutter/material.dart';

class UiUtils {
  // TEMPORARY FOR UNIT TEST PURPOSES ONLY
  int addition(int x, int y) {
    return x + y;
  }
}

(注意:上面是一个示例，实际的类不只是temp函数。)

我的pubspec.yml文件包含以下内容：

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter
  intl: ^0.17.0

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2
  get_it: ^7.1.3
  provider: ^6.0.1
  mockito: ^5.0.16

我有一个这样的dependency locator文件：

import 'package:get_it/get_it.dart';
import 'package:quiz_test/utils/UiUtils.dart';

GetIt dependencyLocator = GetIt.instance;

void setupDependencyLocator() {
  //dependencyLocator.registerSingleton(() => UiUtils());
  dependencyLocator.registerFactory(() => UiUtils());
}

最后，在main.dart中，我有以下内容：

void main() {
  setupDependencyLocator();
  runApp(MyApp());
}

(当然还有更多的代码)。

正如显示的那样，代码运行良好，但是如果我将dependancy_locator文件从当前工厂方法更改为单例(即注释掉一个以启用另一个)，我会得到以下错误：

[VERBOSE-2:ui_dart_state.cc(209)] Unhandled Exception: type '_ServiceFactory<() => UiUtils, void, void>' is not a subtype of type '_ServiceFactory<Object, dynamic, dynamic>' of 'value'
#0      _LinkedHashMapMixin.[]= (dart:collection-patch/compact_hash.dart)
#1      _GetItImplementation._register (package:get_it/get_it_impl.dart:844:35)
#2      _GetItImplementation.registerSingleton (package:get_it/get_it_impl.dart:587:5)
#3      setupDependencyLocator (package:quiz_test/utils/dependency_locator.dart:7:21)
#4      main (package:quiz_test/main.dart:13:3)
#5      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:145:25)
#6      _rootRun (dart:async/zone.dart:1428:13)
#7      _CustomZone.run (dart:async/zone.dart:1328:19)
#8      _runZoned (dart:async/zone.dart:1863:10)
#9      runZonedGuarded (dart:async/zone.dart:1851:12)
#10     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:141:5)
#11     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.<…>

有没有人能告诉我为什么我不能使用单例调用而不能使用工厂调用？我的想法是，我不需要这个类的唯一实例，这是我相信工厂会给我的，对于任何需要它的类，我只需要它的一个实例。

任何帮助都是非常感谢的。

Answer 1

我能够通过执行以下操作来解决此问题：

dependencyLocator.registerSingleton<UiUtils>(UiUtils());

所以，我的dependencyLocator类现在看起来像这样：

import 'package:get_it/get_it.dart';
import 'package:quiz_test/utils/UiUtils.dart';

GetIt dependencyLocator = GetIt.instance;

void setupDependencyLocator() {
  dependencyLocator.registerSingleton<UiUtils>(UiUtils());
}

我希望这能帮助其他人避免被卡住！