通过在rest调用中发送语言环境在后端处理错误消息，对于模板的前端，请使用带有AOT编译功能的Angular i18n.更好的表现 https://angular.io/guide/i18n

Do it at the backend for the error messages by sending the locale in the rest call, for front end in the templates go for the Angular i18n with AOT compilation for a better performance https://angular.io/guide/i18n