多语言配置

多语言 Unicode 规范包含语言 language 、字符表 script 、地区 region ，其中语言用全小写二到三位字母、字符表为首字母大写四位字母、地区全大写两位字母表示。

配置多语言

1. 添加依赖

   执行命令

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

   或编辑 pubspec.yaml 添加依赖

   dependencies:
     flutter:
       sdk: flutter
     flutter_localizations:
       sdk: flutter
     intl: any
   

2. 添加本地化配置

   • 在 pubspec.yaml 中启用 generate 配置

     # The following section is specific to Flutter.
     flutter:
       generate: true # Add this line
     

   • 添加 l10n.yaml 指定本地化生成文件

     arb-dir: lib/l10n
     #template-arb-file: app_en.arb
     template-arb-file: app_zh.arb
     nullable-getter: false
     #懒加载
     #use-deferred-loading: true
     #禁用{}转译
     #use-escaping: false
     #指定生成目录 synthetic-package flase 才能生效
     #synthetic-package: false
     #output-dir: lib/generated
     output-class: AppLocalizations
     output-localization-file: app_localizations.dart
     

   • 在 ${FLUTTER_PROJECT}/lib/l10n 中，添加 app_zh.arb 模板文件

     {
       "helloWorld": "你好!",
       "@helloWorld": {
         "description": "欢迎提示语"
       }
     }
     

   • 执行 flutter gen-l10n 将在 ${FLUTTER_PROJECT}/.dart_tool/flutter_gen/gen_l10n 中看到生成的文件

   • 在调用 MaterialApp 的构造函数时候导入 app_localizations.dart 和使用

     return const MaterialApp(
       title: 'Localizations Sample App',
       localizationsDelegates: S.localizationsDelegates,
       supportedLocales: S.supportedLocales,
       home: MyHomePage(),
     );
     

语言环境操作

切换语言

Localizations.override 提供从在某一个位置设置与应用不同的语言

Localizations.override(
  context: context,
  locale: const Locale('zh'),
  // 
  child: Builder(
    builder: (context) {
      return CalendarDatePicker(
        initialDate: DateTime.now(),
        firstDate: DateTime(1900),
        lastDate: DateTime(2100),
        onDateChanged: (value) {},
      );
    },
  ),
)

获取语言环境

通过调用 Localizations.localeOf() 方法来查看 app 当前的语言环境

Locale myLocale = Localizations.localeOf(context);

指定加载的语言

MaterialApp(
  localeResolutionCallback: (
    locale,
    supportedLocales,
  ) {
    return locale;
  },
);

语言模板arb

占位符 Placeholders

替换 {keyName} 里面内容

"{placeholderName}"

完整例子

{
  "hello": "Hello {userName}",
  "@hello": {
    "description": "A message with a single parameter",
    "placeholders": {
      "userName": {
        "type": "String",
        "example": "Bob"
      }
    }
  }
}

复数 Plurals (数值枚举)

包含一个 num 参数，指定如何在不同情况下返回内容，类似模板如下：

"{countPlaceholder, plural, =0{message0} =1{message1} =2{message2} few{messageFew} many{messageMany} other{messageOther}}"

完整例子

{
  "nWombats": "{count, plural, =0{no wombats} =1{1 wombat} other{{count} wombats}}",
  "@nWombats": {
    "description": "A plural message",
    "placeholders": {
      "count": {
        "type": "num",
        "format": "compact"
      }
    }
  }
}

选择器 Selects (字符串枚举)

包含一个 String 参数，指定如何在不同情况下返回内容，类似模板如下：

"{selectPlaceholder, select, case{message} ... other{messageOther}}"

完整例子

{
  "pronoun": "{gender, select, male{he} female{she} other{they}}",
  "@pronoun": {
    "description": "A gendered message",
    "placeholders": {
      "gender": {
        "type": "String"
      }
    }
  }
}

数字和货币格式

Messages with numbers and currencies

日期格式

Messages with dates

参考

Internationalization | Flutter