Flutter国际化插件internationalization的使用

概述

internationalization 是一个用于轻松实现Flutter项目国际化的插件。它支持多种语言和区域设置，并且可以方便地加载外部JSON文件进行翻译。

基本使用

MaterialApp 配置

在你的MaterialApp中配置支持的语言和地区，以及本地化代理：

import 'package:flutter/material.dart';
import 'package:internationalization/internationalization.dart';

final List<Locale> _supportedLocales = [
  Locale('en', ''),
  Locale('pt', ''),
];

final String _translationsPath = './assets/strings/';

MaterialApp(
  supportedLocales: _supportedLocales,
  localizationsDelegates: [
    InternationalizationDelegate(
      translationsPath: _translationsPath,
      suportedLocales: _supportedLocales,
      addTranslations: (locale) async {
        // 这里可以从外部获取JSON并添加到国际化中。
        // 注意：JSON必须遵循与assets相同的结构。
        return {
          'external_translate': 'Translation from external source',
        };
      },      
    ),
    GlobalMaterialLocalizations.delegate,
    GlobalWidgetsLocalizations.delegate,
    GlobalCupertinoLocalizations.delegate,
  ],
);

在pubspec.yaml中暴露JSON文件夹

确保在pubspec.yaml中正确配置资源路径：

flutter:
  uses-material-design: true
  assets:
    - ./assets/strings/en/
    - ./assets/strings/pt/

文件夹结构

请按照以下结构创建文件夹，确保与pubspec.yaml中的配置一致：

翻译示例

简单字符串翻译

"simple_string".translate(context, translationContext: _translationContext),
context.translate('interpolation_string', translationContext: _translationContext, args: ["( ͡° ͜ʖ ͡°)"]),
context.translate('interpolation_string_with_named_args', translationContext: _translationContext, namedArgs: {"named_arg_key": "( ͡° ͜ʖ ͡°)"}),

复数形式翻译

context.translate('simple_plurals', translationContext: _translationContext, pluralValue: 0),
context.translate('simple_plurals', translationContext: _translationContext, pluralValue: 1),
context.translate('simple_plurals', translationContext: _translationContext, pluralValue: 123456789),

插值复数形式翻译

context.translate('interpolation_plurals', translationContext: _translationContext, pluralValue: 0, args: ["( ͡° ͜ʖ ͡°)"]),
context.translate('interpolation_plurals', translationContext: _translationContext, pluralValue: 1, args: ["( ͡° ͜ʖ ͡°)"]),
context.translate('interpolation_plurals', translationContext: _translationContext, pluralValue: 123456789, args: ["123456789"]),

NumberFormat & DateFormat

这些功能来自intl库，已经被集成到Internationalization中：

• NumberFormat
• DateFormat

完整示例Demo

下面是一个完整的示例项目，展示如何使用internationalization插件：

pubspec.yaml

name: internationalization_demo
description: A demo for internationalization in Flutter.

dependencies:
  flutter:
    sdk: flutter
  internationalization: ^latest_version # 替换为最新版本号

flutter:
  uses-material-design: true
  assets:
    - ./assets/strings/en/
    - ./assets/strings/pt/

lib/main.dart

import 'package:flutter/material.dart';
import 'package:internationalization/internationalization.dart';

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

class MyApp extends StatelessWidget {
  final List<Locale> _supportedLocales = [
    Locale('en', ''),
    Locale('pt', ''),
  ];

  final String _translationsPath = './assets/strings/';

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Internationalization Demo',
      supportedLocales: _supportedLocales,
      localizationsDelegates: [
        InternationalizationDelegate(
          translationsPath: _translationsPath,
          suportedLocales: _supportedLocales,
          addTranslations: (locale) async {
            return {
              'external_translate': 'Translation from external source',
            };
          },      
        ),
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Internationalization Demo"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text("simple_string".translate(context)),
            Text(context.translate('interpolation_string', args: ["( ͡° ͜ʖ ͡°)"])),
            Text(context.translate('interpolation_string_with_named_args', namedArgs: {"named_arg_key": "( ͡° ͜ʖ ͡°)"})),
            Text(context.translate('simple_plurals', pluralValue: 0)),
            Text(context.translate('simple_plurals', pluralValue: 1)),
            Text(context.translate('simple_plurals', pluralValue: 123456789)),
          ],
        ),
      ),
    );
  }
}