从Hibernate中的数据库加载属性？

Question

我有三个类具有类层次结构

> < Li > < p > < code > parent class . Java

having commons properties used for both ChildClass1 and ChildClass2.

子类 1 扩展父类

具有用于此ChildClass1的属性，它还使用来自父类的一些常见属性

< code>ChildClass2扩展ParentClass

具有用于此子类2的属性，它还使用父类中的一些公共属性

所有这些属性都包含在两列表中

**Key               value**     Type
---------------------------------------
propertyKey1    propertyValue1   Child1
propertyKey2    propertyValue2   Child1
propertyKey3    propertyValue3   Child2
propertyKey4    propertyValue4   Child2
propertyKey5    propertyValue5   CommonPorperty
..              ..               ..
propertyKeyn    propertyValuen   ..

现在我不确定如何从Hibernate继承加载它们？

为愚蠢的问题道歉...

提前谢谢

Answer 1

您需要添加一个列“Discriminator”，以通知Hibernate在使用多个类型处理同一个表时应该加载哪个实例。参见示例：

@Entity
@org.hibernate.annotations.Entity(dynamicInsert = true, dynamicUpdate = true)
@Table(name = "PARENT_TABLE")
@DiscriminatorColumn(name = "TYPE", discriminatorType = DiscriminatorType.INTEGER)
public abstract class ParentEntity implements java.io.Serializable {

    private long id;
    private String commonValue1;

    @Id      
    @Column(name = "ID", nullable = false)
    public long getId() {
        return id;
    }

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

    @Column(name = "Common_Value1")
    public String getCommonValue1(){
        return commonValue1;
    }

    public void setCommonValue1(String commonValue1){
        this.commonValue1 = commonValue1;
    }
}


@Entity
@DiscriminatorValue("1")
public class ChildEntity1 extends ParentEntity {

    private String child1Value;

    @Column(name = "Child1_Value")
    public String getChild1Value(){
        return child1Value;
    }

    public void setChild1Value(String child1Value){
        this.child1Value = child1Value;
    }
}

@Entity
@DiscriminatorValue("2")
public class ChildEntity2 extends ParentEntity {

    private String child2Value;

    @Column(name = "Child2_Value")
    public String getChild2Value(){
        return child2Value;
    }

    public void setChild2Value(String child2Value){
        this.child2Value = child2Value;
    }
}