java - 映射结构 : Dealing with HashMap entries as source

Question

这是我的源对象:

public class Record {

    public final long captureTime;
    public final String environnement;
    public final String bundle;
    public final String type;
    public final String id;
    public final Map<String,Object> meta;

}

这是我的目标对象:

public class MappedRecord {

    public final long captureTime;
    public final String environnement;
    public final String bundle;
    public final String type;
    public final String id;
    public final String ip;
    public final String server;

}

我的映射器如下所示:

public interface RecordMapper {

    RecordMapper MAPPER = Mappers.getMapper( RecordMapper.class );


    @Mappings({
        @Mapping(source = "captureTime", target = "captureTime"),
        @Mapping(source = "environnement", target = "environnement"),
        @Mapping(source = "bundle", target = "bundle"),
        @Mapping(source = "type", target = "type"),
        @Mapping(source = "id", target = "id"),
        @Mapping(expression = "java((String) r.meta.get(\"ip\"))", target = "ip"),
        @Mapping(expression = "java((String) r.meta.get(\"server\"))", target = "server"),
    })

    MappedRecord toMappedRecord(Record r);

}

目前它运行良好，但我想知道是否有更“优雅”的方式将 map 条目设置为源。因为有了这个我没有设法使用“qualifiedByName”属性添加转换函数，看起来它只能在指定“源”时工作。我误解了什么吗？

我尝试了以下方法但没有得到满意的结果:

• 为我的 Record 类中的特定字段覆盖 getter

• 添加具有“qualifiedByName”属性的转换函数。像这样的东西:

  @Named("metaGetter")
  default String dataGetter (String property) {
      return (String) r.meta.get(property);
  }
  

  但显然这不会编译，因为属性名称作为正确的来源无效。

感谢您的宝贵时间。

Answer 1

编写自己的限定符:

public class MappingUtil {
    @Qualifier
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.SOURCE)
    public @interface Ip {
    }
    @Qualifier
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.SOURCE)
    public static @interface Server {
    }
    @Ip
    public String ip(Map<String, Object> in) {

        return (String)in.get("ip");
    }
    @Server
    public String server(Map<String, Object> in) {

        return (String)in.get("server");
    }
}

然后只需添加到映射中:

@Mapper( uses = MappingUtil.class )
public interface SourceTargetMapper {

    SourceTargetMapper MAPPER = Mappers.getMapper( SourceTargetMapper.class );

    @Mappings( {
        @Mapping(source = "map", target = "ip", qualifiedBy = MappingUtil.Ip.class ),
        @Mapping(source = "map", target = "server", qualifiedBy = MappingUtil.Server.class ),
    } )
    Target toTarget( Source s );
}