Hibernate复合主键包含复合外键,如何映射

在B的pk类中将A的实体对象设置为@manytoone。

如果你有

Class A
Class APK - A's Primary Key

Class B
Class BPK - B's primary Key.

BPK 将包含 A 作为属性

@Embeddable
public class BPK implements serializable {
  ....
  private A a;

  @ManyToOne(fetch=FetchType.EAGER)
  @JoinColumns ({
    @JoinColumn(name="...", referencedColumnName = "..."),
    @JoinColumn(name="...", referencedColumnName = "..."),
    ...
  })
  public getA() {
    return this.a;
  }
}

从 documentation

@可嵌入继承的访问类型 它的拥有实体,除非休眠 特定注释@accesstype为 已使用。复合外键(如果不是 使用默认敏感值) 在关联上使用 @joinColumns元素,即 基本上是@joincolumn的数组。它 被认为是 快速引用列名称 明确地。否则,休眠将 假设您使用相同的顺序 列与主键中的列相同 宣言。

如果你的复合主键有 只有 代理键,使用@embeddableid

@Embeddable
public class CompoundIdA implements Serializable {

    private Integer field0;
    private Integer field1;
    private Integer field2;
    private Integer field3;

    @Column(name="FIELD_0")
    public Integer getField0() {
        return this.field0;
    }

    @Column(name="FIELD_1")
    public Integer getField1() {
        return this.field1;
    }

    @Column(name="FIELD_2")
    public Integer getField2() {
        return this.field2;
    }

    @Column(name="FIELD_3")
    public Integer getField3() {
        return this.field3;
    }

    public boolean equals(Object o) {
        if(o == null)
            return false;

        if(!(o instanceof CompoundIdA))
            return false;

        final CompoundIdA other = (CompoundIdA) o;
        if(!(getField0().equals(other.getField0()))
            return false;

        if(!(getField1().equals(other.getField1()))
            return false;

        if(!(getField2().equals(other.getField2()))
            return false;

        if(!(getField2().equals(other.getField2()))
            return false;

        return true;
    }

    // hashcode impl

}

在课堂上,我们有

@Entity
public class ClassA {

    private CompoundIdA compoundIdA;

    @EmbeddedId
    public CompoundIdA getCompoundIdA() {
        return this.CompoundIdA;
    }

}

如果你的复合主键有 自然键和代理键 ,再次使用@embeddableid

// Let's suppose field0 and field1 are both natural keys
@Entity
public class ClassA {

    private CompoundIdA compoundIdA;

    private Integer field0;
    private Integer field1;

    @EmbeddedId
    public CompoundIdA getCompoundIdA() {
        return this.CompoundIdA;
    }

    @Column(name="FIELD_0", insertable=false, updateable=false)
    public Integer getField0() {
        return this.field0;
    }

    @Column(name="FIELD_1", insertable=false, updateable=false)
    public Integer getField1() {
        return this.field1;
    }

}

通知 必须设置insertable=false和updateable=false 因为多个属性共享同一列。否则,Hibernate会抱怨一些错误。

如果你的复合主键有 只有 自然键,使用@idclass

@Entity
@IdClass(CompoundIdA.class)
public class ClassA {

    private Integer field0;
    private Integer field1;
    private Integer field2;
    private Integer field3;

    @Id
    @Column(name="FIELD_0")
    public Integer getField0() {
        return this.field0;
    }

    @Id
    @Column(name="FIELD_1")
    public Integer getField1() {
        return this.field1;
    }

    @Id
    @Column(name="FIELD_2")
    public Integer getField2() {
        return this.field2;
    }

    @Id
    @Column(name="FIELD_3")
    public Integer getField3() {
        return this.field3;
    }

}

在B类中,您可以使用如上所示的方法, 但是 如果要定义@manytoone属性, 你必须设置 insertable=false和updateable=false如下

@Entity
public class ClassB {

    private ClassA classA;

    @ManyToOne
    @JoinColumns ({
        @JoinColumn(name="FIELD_0", referencedColumnName="FIELD_0", insertable=false, updateable=false),
        @JoinColumn(name="FIELD_1", referencedColumnName="FIELD_1", insertable=false, updateable=false),
        @JoinColumn(name="FIELD_2", referencedColumnName="FIELD_2", insertable=false, updateable=false),
        @JoinColumn(name="FIELD_3", referencedColumnName="FIELD_3", insertable=false, updateable=false)
    })
    public ClassA getClassA() {
        return this.classA;
    }

}

当做,