应该是 DDD 中域的本地化部分

在遵循 DDD 概念的同时，我正在努力决定是否应该让我的域本地化意识？我提出了两个解决方案来解决这个问题。两者都使域本地化能够在不同的地方实现。我是否应该将本地化文本放入域中？分享您对此问题的解决方案或我的两个示例的优缺点。谢谢。

实施例1

class Persion {

  String name;

  // other fields ommited

  void rename(String newName) {
    String oldName = this.name;
    this.name = newName

    // publish event with old name and new name
  }

  String name() {
    return name;
  }
}

class PersionRepository {

  void store(Persion persion) {
    Locale loc = LocaleContextHolder.get().getLocale();

    // store object to DAO - create/update fields for context locale
  }

  // other methods ommited
}

实施例2

class Persion {

  Map<Locale, String> name;

  // other fields ommited

  void rename(String newName) {
    Locale locale = LocaleContextHolder.get().getLocale();
    String oldName = this.name.put(locale, newName);

    // publish event with old name and new name
  }

  String name() {
    Locale locale = LocaleContextHolder.get().getLocale();
    return this.name.get(locale);
  }
}

class PersionRepository {

  void store(Persion persion) {
    // store object to DAO - create/update fields for all locales
  }

  // other methods ommited
}

在大多数情况下，最好的选择是从域中删除本地化。

域类应该只包含与其不变量相关的数据，因为它们负责业务规则。要检索本地化描述，请使用投影 DTO 和应用服务。

你可以使用这样的东西：

public final class VatCode {
    private final String _code;
    public VatCode(String code)
    {
        // VAT code validation here...
        _code = code;
    }

    @Override
    public String toString() {
        return _code;
    }

    @Override
    public boolean equals(Object obj) {
        // ...
    }

    @Override
    public int hashCode() {
        // ...
    }
}

public class Person {
    private final VatCode _identifier;

    public Person(VatCode identifier)
    {
        _identifier = identifier;
    }

    // some command and some query here...
}

public class PersonDTO {
    private final String _vatCode;
    private final String _personalDescription;

    public PersonDTO(String _vatCode, String _personalDescription) {
        this._vatCode = _vatCode;
        this._personalDescription = _personalDescription;
    }
    // other fields here...

    public String getVatCode()
    {
        return _vatCode;
    }

    public String getPersonalDescription()
    {
        return _personalDescription;
    }

    // some more getter here
}

public interface LocalizedPersonalInformationService {
    PersonDTO getInformationOf(VatCode person, Locale localization) throws ProperExceptionList;
}

That is:

• 像一个VatCodevalueobject（覆盖 equals、hashCode 和 toString）来标识Person entity
• a Person实体，持有确保所需的最小数据量商业不变量并暴露一组命令和查询 http://epic.tesio.it/doc/manual/command_query_separation.html
• a PersonDTO带有有用的描述（有些人称之为读取模型 http://gorodinski.com/blog/2012/04/25/read-models-as-a-tactical-pattern-in-domain-driven-design-ddd/)
• a LocalizedPersonalInformationService能够提供PersonDTOs.
• 和（显然）所有needed http://epic.tesio.it/2012/12/05/exceptions-are-the-norm.html 例外情况 http://epic.tesio.it/2013/03/04/exceptions-are-terms-ot-the-ubiquitous-language.html... :-)