Hibernate Annotations(四)

普通一对多(延迟加载方式)

@OneToMany(mappedBy = "troop", cascade = {CascadeType.ALL}, fetch = FetchType.LAZY)
    @OrderBy(clause = "name desc")
    public Set<Soldier> getSoldiers() {
        return soldiers;
    }

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "troop_fk")
    public Troop getTroop() {
        return troop;
    }

DeleteOrphan模式

@OneToMany(mappedBy = "troop", cascade = ...{CascadeType.ALL}, fetch = FetchType.LAZY)
    @OrderBy(clause = "name desc")
    @org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
    public Set<Soldier> getSoldiers() ...{
        return soldiers;
    }

    troop.getSoldiers().clear();
    s = openSession();
    tx = s.beginTransaction();
    s.merge( troop );
    tx.commit();
    s.close();

OneToManySet

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinColumn(name = "CUST_ID")
    @Sort(type = SortType.COMPARATOR, comparator = TicketComparator.class)
    public SortedSet<Ticket> getTickets() ...{
        return tickets;
    }

   public class TicketComparator implements Comparator<Ticket> ...{

    public int compare(Ticket ticket, Ticket ticket1) ...{
        if ( ticket == null || ticket1 == null ) ...{
            throw new IllegalStateException( "Ticket comparison only available through non null        tickets" );
        }
    return ticket1.getNumber().length() - ticket.getNumber().length();

    }
}

OneToManyCollection

    @OneToMany(targetEntity = org.hibernate.test.annotations.Discount.class,
            cascade = CascadeType.ALL, mappedBy = "owner")
    @Cascade(...{ALL})
    public Collection getDiscountTickets() ...{
        return discountTickets;
    }

JoinColumns

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "parent")
    @BatchSize(size = 5)
    @javax.persistence.OrderBy("favoriteSuperhero asc, favoriteSinger desc")
    public Set<Child> children;

    @ManyToOne()
    @JoinColumns(...{
    @JoinColumn(name = "parentCivility", referencedColumnName = "isMale"),
    @JoinColumn(name = "parentLastName", referencedColumnName = "lastName"),
    @JoinColumn(name = "parentFirstName", referencedColumnName = "firstName")
            })
    public Parent parent;
    @Column(name = "fav_sup_hero")
    public String favoriteSuperhero;
    @Column(name = "fav_singer")
    public String favoriteSinger;

注:cascade的值只能从CascadeType.PERSIST（级联新建）、CascadeType.REMOVE（级联删除）、CascadeType.REFRESH（级联刷新）、CascadeType.MERGE（级联更新）中选择一个或多个。还有一个选择是使用CascadeType.ALL，表示选择全部四项。

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