FlutterInternational国际化，Localization本地化，使用Intl

新建项目&＃xff0c;得到一个示例工程。本例中使用intl包来管理文字资源。

项目地址&＃xff1a; https://github.com/RustFisher/localization_demo

步骤&＃xff1a;

• 添加依赖项 - intl
• 创建文字资源文件
• 生成arb文件
  • 新增和修改arb文件
• 根据arb生成dart文件
• 创建localization代理&＃xff0c;新建一个类继承LocalizationsDelegate&＃xff0c;和文字资源文件联系起来
• MaterialApp中添加本地化代理和语言类型
• 使用文字资源

添加依赖项

pubspec.yaml添加依赖项flutter_localizations&＃xff0c;然后运行一下flutter packages get。

dependencies:flutter:sdk: flutter
# 添加下面的依赖项flutter_localizations:sdk: flutterintl: 0.15.6intl_translation: 0.16.7

编辑dart文件

新建app_strings.dart文件。

import &＃39;dart:async&＃39;;import &＃39;package:intl/intl.dart&＃39;;
import &＃39;package:flutter/widgets.dart&＃39;;class AppStrings {AppStrings(Locale locale) : _localeName &＃61; locale.toString();final String _localeName;static Future load(Locale locale) {return initializeMessages(locale.toString()).then((Object _) {return new AppStrings(locale);});}static AppStrings of(BuildContext context) {return Localizations.of(context, AppStrings);}String title() {return Intl.message(&＃39;Localization Demo&＃39;,name: &＃39;title&＃39;,desc: &＃39;应用标题&＃39;,locale: _localeName,);}String click() &＃61;> Intl.message(&＃39;Click&＃39;,name: &＃39;click&＃39;,desc: &＃39;点击&＃39;,locale: _localeName,);String helloFromDemo() &＃61;> Intl.message(&＃39;Hello~&＃39;,name: &＃39;helloFromDemo&＃39;,desc: &＃39;一句问候&＃39;,locale: _localeName,);
}

此时initializeMessages方法会显示警告&＃xff0c;暂时不用管&＃xff0c;生成arb文件后再添加引用。

生成arb文件

进入项目目录&＃xff0c;运行intl的命令。

/e/ws/localization_demo
$ flutter pub pub run intl_translation:extract_to_arb --output-dir&＃61;lib/l10n lib/app_strings.dart

生成l10n/intl_messages.arb&＃xff0c;内容如下。可以看出是JSON格式的文本。

{"&＃64;&＃64;last_modified": "2018-07-15T22:13:19.218221","title": "Localization Demo","&＃64;title": {"description": "应用标题","type": "text","placeholders": {}},"click": "Click","&＃64;click": {"description": "点击","type": "text","placeholders": {}},"helloFromDemo": "Hello~","&＃64;helloFromDemo": {"description": "一句问候","type": "text","placeholders": {}}
}

新增和修改arb文件

前面生成了l10n/intl_messages.arb&＃xff0c;我们可以把它当成模板。复制粘贴一下&＃xff0c;同目录下得到intl_en.arb和intl_zh.arb。文件名规则可以自己定。
以intl_zh.arb为例&＃xff1a;

{"&＃64;&＃64;last_modified": "2018-07-15T22:13:19.218221","title": "国际化示例App","&＃64;title": {"description": "应用标题","type": "text","placeholders": {}},"click": "点击","&＃64;click": {"description": "点击","type": "text","placeholders": {}},"helloFromDemo": "你好呀~","&＃64;helloFromDemo": {"description": "一句问候","type": "text","placeholders": {}}
}

这里也可以把intl_messages.arb删掉。本例保留这个文件。

根据arb生成dart文件

$ flutter pub pub run intl_translation:generate_from_arb --output-dir&＃61;lib/l10n \--no-use-deferred-loading lib/app_strings.dart lib/l10n/intl_*.arbNo &＃64;&＃64;locale or _locale field found in intl_en, assuming &＃39;en&＃39; based on the file name.
No &＃64;&＃64;locale or _locale field found in intl_messages, assuming &＃39;messages&＃39; based on the file name.
No &＃64;&＃64;locale or _locale field found in intl_zh, assuming &＃39;zh&＃39; based on the file name.

暂时无视警告。
此时在app_strings.dart中添加对l10n/intl_messages.arb的引用。

import &＃39;package:localization_demo/l10n/messages_all.dart&＃39;;

警告消失~

更新了arb文件后&＃xff0c;需要重新生成dart文件。

创建localization代理

创建localizations_delegate.dart。新建AppLocalizationsDelegate类继承LocalizationsDelegate&＃xff0c;复写方法。
泛型指定为前面的AppStrings。

import &＃39;dart:async&＃39;;import &＃39;package:flutter/widgets.dart&＃39;;
import &＃39;package:localization_demo/app_strings.dart&＃39;;class AppLocalizationsDelegate extends LocalizationsDelegate {&＃64;overrideFuture load(Locale locale) {return AppStrings.load(locale);}&＃64;overridebool isSupported(Locale locale) &＃61;>[&＃39;zh&＃39;, &＃39;en&＃39;].contains(locale.languageCode); // 支持的类型要包含App中注册的类型&＃64;overridebool shouldReload(AppLocalizationsDelegate old) &＃61;> false;
}

MaterialApp中添加本地化代理和语言类型

class MyApp extends StatelessWidget {&＃64;overrideWidget build(BuildContext context) {return new MaterialApp(title: &＃39;Flutter Demo&＃39;,theme: new ThemeData(primarySwatch: Colors.blue,),localizationsDelegates: [AppLocalizationsDelegate(), // 我们定义的代理GlobalMaterialLocalizations.delegate,GlobalWidgetsLocalizations.delegate,],supportedLocales: [ // 支持的语言类型const Locale(&＃39;en&＃39;, &＃39;US&＃39;), // Englishconst Locale(&＃39;zh&＃39;, &＃39;&＃39;),],home: new MyHomePage(title: &＃39;Flutter Demo Home Page&＃39;),);}
}

使用文字资源

获取到AppStrings的实例。

AppStrings appStrings &＃61; AppStrings.of(context);print(appStrings); // logcat: I/flutter ( 7478): Instance of &＃39;AppStrings&＃39;

注意&＃xff0c;在MaterialApp中使用文字资源时&＃xff0c;因为context的关系&＃xff0c;要使用onGenerateTitle。

onGenerateTitle: (context) {return AppStrings.of(context).title();},

支持语言的类型

代理isSupported方法中的语言类型最好是和App中supportedLocales的一致

&＃64;overridebool isSupported(Locale locale) &＃61;>[&＃39;zh&＃39;, &＃39;en&＃39;].contains(locale.languageCode);// App中&＃96;supportedLocales&＃96;supportedLocales: [const Locale(&＃39;en&＃39;, &＃39;US&＃39;), // Englishconst Locale(&＃39;zh&＃39;, &＃39;&＃39;),],

否则可能出现获取不到AppStrings的异常。

参考&＃xff1a;

• https://flutter.io/tutorials/internationalization/