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Flutter - International 国际化,Localization 本地化, 使用Intl

来源:必赢娱乐官方客户端   发布时间:2019-06-24   点击量:21

新建项目,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: https://github.com/RustFisher/localization_demo

步骤:

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,新建一个类继承LocalizationsDelegate,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,然后运行一下flutter packages get

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

编辑dart文件

新建app_strings.dart文件。

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

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

生成arb文件

进入项目目录,运行intl的命令。

/e/ws/localization_demo$ flutter pub pub run intl_translation:extract_to_arb --output-dir=lib/l10n lib/app_strings.dart

生成l10n/intl_messages.arb,内容如下。可以看出是JSON格式的文本。

{ "@@last_modified": "2018-07-15T22:13:19.218221", "title": "Localization Demo", "@title": { "description": "应用标题", "type": "text", "placeholders": {} }, "click": "Click", "@click": { "description": "点击", "type": "text", "placeholders": {} }, "helloFromDemo": "Hello~", "@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,我们可以把它当成模板。复制粘贴一下,同目录下得到intl_en.arbintl_zh.arb。文件名规则可以自己定。intl_zh.arb为例:

{ "@@last_modified": "2018-07-15T22:13:19.218221", "title": "国际化示例App", "@title": { "description": "应用标题", "type": "text", "placeholders": {} }, "click": "点击", "@click": { "description": "点击", "type": "text", "placeholders": {} }, "helloFromDemo": "你好呀~", "@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=lib/l10n --no-use-deferred-loading lib/app_strings.dart lib/l10n/intl_*.arbNo @@locale or _locale field found in intl_en, assuming "en" based on the file name.No @@locale or _locale field found in intl_messages, assuming "messages" based on the file name.No @@locale or _locale field found in intl_zh, assuming "zh" 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 "package:localization_demo/l10n/messages_all.dart";

警告消失~

更新了arb文件后,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,复写方法。泛型指定为前面的AppStrings

import "dart:async";import "package:flutter/widgets.dart";import "package:localization_demo/app_strings.dart";class AppLocalizationsDelegate extends LocalizationsDelegate<AppStrings> { @override Future<AppStrings> load(Locale locale) { return AppStrings.load(locale); } @override bool isSupported(Locale locale) => ["zh", "en"].contains(locale.languageCode); // 支持的类型要包含App中注册的类型 @override bool shouldReload(AppLocalizationsDelegate old) => false;}

MaterialApp中添加本地化代理和语言类型

class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return new MaterialApp( title: "Flutter Demo", 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("en", "US"), // English const Locale("zh", ""), ], home: new MyHomePage(title: "Flutter Demo Home Page"), ); }}

使用文字资源

获取到AppStrings的实例。

AppStrings appStrings = AppStrings.of(context); print(appStrings); // logcat: I/flutter ( 7478): Instance of "AppStrings"

注意,在MaterialApp中使用文字资源时,因为context的关系,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

@override bool isSupported(Locale locale) => ["zh", "en"].contains(locale.languageCode);// App中`supportedLocales` supportedLocales: [ const Locale("en", "US"), // English const Locale("zh", ""), ],

否则可能出现获取不到AppStrings的异常。

参考:

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

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