Hibernate Annotations(二)

复合主键的应用 (EmbeddedId)

主表

@Entity
public class A implements Serializable...{

    @EmbeddedId
    private AId aId;

    public AId getAId() ...{
        return aId;
    }

    public void setAId(AId aId) ...{
        this.aId = aId;
    }
}
复合主键

@Embeddable
public class AId implements Serializable ...{

    @OneToOne
    @JoinColumn( name = "bid" )
    private B b;

    @OneToOne
    @JoinColumn( name = "cid" )
    private C c;

    public B getB() ...{
        return b;
    }

    public void setB(B b) ...{
        this.b = b;
    }

    public C getC() ...{
        return c;
    }

    public void setC(C c) ...{
        this.c = c;
    }
}
关联表

@Entity
public class B ...{

    @Id
    @GeneratedValue
    private Long id;

    public Long getId() ...{
        return id;
    }

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

@Entity
public class C ...{

    @Id
    @GeneratedValue
    private Long id;

    public Long getId() ...{
        return id;
    }

    public void setId(Long id) ...{
        this.id = id;
    }
}
复合主键的应用 (IdClass)

主表

@Entity
@IdClass(OrderLinePk.class)
public class OrderLine ...{
    @Id
    public Order order;
    @Id
    public Product product;
}
主键类

public class OrderLinePk implements Serializable ...{
    @ManyToOne
    @JoinColumn(name = "foo", nullable = false)
    public Order order;
    @ManyToOne
    @JoinColumn(name = "bar", nullable = false)
    public Product product;   
}

关联表

@Entity
public class Product ...{
    @Id
    public String name;
}

@Entity
@Table(name = "OrderTableFoobar")
public class Order ...{
    @Id
    @GeneratedValue
    public Integer id;
}