如何在Hibernate中从非实体子类中持久化实体

Question

我试图将实体扩展为非实体,用于填充超类的字段.问题是,当我尝试保存它时,Hibernate会抛出MappingException.这是因为即使我将ReportParser强制转换为Report,运行时实例仍然是ReportParser,因此Hibernate抱怨它是一个未知实体.

@Entity
@Table(name = "TB_Reports")
public class Report
{
   Long id;
   String name;
   String value;

   @Id
   @GeneratedValue
   @Column(name = "cReportID")
   public Long getId()
   {
      return this.id;
   }

   public void setId(Long id)
   {
      this.id = id;
   }

   @Column(name = "cCompanyName")
   public String getname()
   {
      return this.name;
   }

   public void setName(String name)
   {
      this.name = name;
   }

   @Column(name = "cCompanyValue")
   public String getValue()
   {
      return this.name;
   }

   public void setValue(String value)
   {
      this.value = value;
   }
}

ReportParser仅用于填写字段.

public class ReportParser extends report
{
   public void setName(String htmlstring)
   {
      ...
   }

   public void setValue(String htmlstring)
   {
      ...
   }
}

尝试将其转换为报告并保存

...
ReportParser rp = new ReportParser();
rp.setName(unparsed_string);
rp.setValue(unparsed_string);
Report r = (Report)rp;
this.dao.saveReport(r);

我在移动到ORM之前使用过这种模式,但是我无法弄清楚如何使用Hibernate.可能吗？

Answer 1

是否绝对有必要对实体进行子类化？您可以使用构建器模式：

public class ReportBuilder {
    private Report report;
    public ReportBuilder() {
        this.report = new Report();
    }
    public ReportBuilder setName(String unparsedString) {
        // do the parsing
        report.setName(parsedString);
        return this;
    }
    public ReportBuilder setValue(String unparsedString) {
        // do the parsing
        report.setValue(parsedString);
        return this;
    }
    public Report build() {
        return report;
    }
}

Report report = new ReportBuilder()
                   .setName(unparsedString)
                   .setValue(unparsedString)
                   .build();
dao.saveReport(report);