Flutter - 国际化

环境

Flutter 3.29
macOS Sequoia 15.4.1
Xcode 16.3

配置

安装依赖包

默认情况下，Flutter只提供美式英语的本地化，可以通过flutter_localizations这个package来实现国际化。

创建flutter工程后执行

¥ flutter pub add flutter_localizations --sdk=flutter
¥ flutter pub add intl:any

执行后的pubspec.yaml文件的效果

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.8
  flutter_localizations:
    sdk: flutter
  intl: any

安装对应的package

¥ flutter pub get 

pubspec.yaml文件

在 Flutter 项目的根目录中添加一个新的 yaml 文件，命名为 l10n.yaml，其内容如下：

arb-dir: lib/common/localization/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart 

1. 将 应用资源包 (.arb) 的输入路径指定为 ${FLUTTER_PROJECT}/lib/common/localization/l10n。
2. 将英文的语言模板设定为 app_en.arb。
3. 指定 Flutter 生成本地化内容到 app_localizations.dart 文件。

要在pubspec.yaml 文件中，设置generate为true，执行命令时才会生成对应的app_localizations.dart文件

flutter:
    generate: true

指定这个是为了生成项目时能自动生成对应的.dart代码文件

在 ${FLUTTER_PROJECT}/lib/common/localization/l10n 添加 app_en.arb 模板文件

{
   
   
    "helloWorld": "Hello World!"
}

在同一目录下添加中文的模板文件 app_zh.arb

{
   
   
    "helloWorld":"你好，世界"
}

执行命令生成.dart文件

¥ flutter run

运行报错

Synthetic package output (package:flutter_gen) is deprecated: https://flutter.dev/to/flutter-gen-deprecation. In a future release, synthetic-package will
default to `false` and will later be removed entirely.
Generating synthetic localizations package failed with 1 error:

Error: Attempted to generate localizations code without having the flutter: generate flag turned on.
Check pubspec.yaml and ensure that flutter: generate: true has been added and rebuild the project. Otherwise, the localizations source code will not be
importable.

有两个问题,一个是使用flutter_gen生成synthetic package 的方式已经过期,推荐使用在 Flutter 项目中指定的目录下生成国际化资源代码文件。该标志默认为 true，还有一个报错是因为pubspec.yaml没有设置允许自动生成代码

解决方案: l10n.yaml文件中追加设置不使用Synthetic package的方式生成国际化资源文件

synthetic-package: false

解决方案: pubspec.yaml设置允许自动生成代码

flutter:
  generate: true

重新运行 flutter run

报错消失,并在l10n目录下生成对应的.dart代码文件

打开 app_localizations.dart

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:intl/intl.dart' as intl;

import 'app_localizations_en.dart';
import 'app_localizations_zh.dart';


abstract class AppLocalizations {
   
   
  AppLocalizations(String locale) : localeName = intl.Intl.canonicalizedLocale(locale.toString());

  final String localeName;

  static AppLocalizations? of(BuildContext context) {
   
   
    return Localizations.of<AppLocalizations>(context, AppLocalizations);
  }

  static const LocalizationsDelegate<AppLocalizations> delegate = _AppLocalizationsDelegate();