输入框长按选项菜单复制、粘贴、剪切、全选部分默认为英文，对于只需要对此部分做中文本地化，不需要考虑其他语言及全局本地化的项目，可以直接自定义一个本地化代理方法进行覆盖，不需要额外下载插件

// 自定义本地化代理
class _ChineseLocalizationsDelegateextends LocalizationsDelegate<MaterialLocalizations> {const _ChineseLocalizationsDelegate();@overridebool isSupported(Locale locale) => true;@overrideFuture<MaterialLocalizations> load(Locale locale) async {return const _ChineseMaterialLocalizations();}@overridebool shouldReload(_ChineseLocalizationsDelegate old) => false;
}// 自定义 MaterialLocalizations
class _ChineseMaterialLocalizations extends DefaultMaterialLocalizations {const _ChineseMaterialLocalizations();@overrideString get copyButtonLabel => '复制';@overrideString get pasteButtonLabel => '粘贴';@overrideString get cutButtonLabel => '剪切';@overrideString get selectAllButtonLabel => '全选';
}

然后将其添加到main函数中的主app中

return MaterialApp(locale: Locale('zh', 'CH'),localizationsDelegates: const [_ChineseLocalizationsDelegate(),DefaultWidgetsLocalizations.delegate,DefaultMaterialLocalizations.delegate,],supportedLocales: [const Locale('zh', 'CH'),],);