java - Hibernate merge 同时进行插入和删除

Question

我真的是 Hibernate 的新手。这是我的问题:

我有一个中央数据库，可以重新组合来自许多代理的数据。

每个代理必须只将与他有关的数据存储到他自己的数据库中。

我需要在服务器/代理之间同步数据

我有两个案例:

1)第一次同步(agent上的DB为空)

2)完全同步(删除/添加新元素/更改等...)

我有一个盒子实体和一个用户实体，它们之间的关系是多对多

盒子实体(部分)是这样描述的:

 @Entity
//@Cache(usage=CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
@Table(name="box")
@NamedQuery(name="Box.findAll", query="SELECT b FROM Box b")
@JsonIdentityInfo(generator= ObjectIdGenerators.IntSequenceGenerator.class, property="@id")
public class Box extends BasicData implements Serializable {
....

//bi-directional many-to-many association to User
@ManyToMany(mappedBy="boxs")
private Set<User> users;

//bi-directional many-to-one association to BoxUser
@OneToMany(mappedBy="box", orphanRemoval=true)
@Cascade({ org.hibernate.annotations.CascadeType.ALL})
private Set<BoxUser> boxUsers;

getters /setters
....

BoxUser 实体的描述(部分)如下:

public class BoxUser implements Serializable {
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private BoxUserPK id;

    //bi-directional many-to-one association to Box
    @ManyToOne
    @JoinColumn(name="boxid", nullable=false, insertable=false, updatable=false)
    @Cascade({ org.hibernate.annotations.CascadeType.ALL})
    private Box box;

    //bi-directional many-to-one association to User
    @ManyToOne
    @JoinColumn(name="userid", nullable=false, insertable=false, updatable=false)
    @Cascade({ org.hibernate.annotations.CascadeType.ALL})
    private User user;

    getters /setters
    ....

用户实体(部分)是这样描述的:

public class User extends BasicData implements Serializable {
    private static final long serialVersionUID = 1L;

    //bi-directional many-to-one association to BoxUser
    @OneToMany(mappedBy="user")
    private Set<BoxUser> boxUsers;

    //bi-directional many-to-many association to Box
    @ManyToMany
    @JoinTable(
        name="box_user"
        , joinColumns={
            @JoinColumn(name="userid", nullable=false)
            }
        , inverseJoinColumns={
            @JoinColumn(name="boxid", nullable=false)
            }
        )
    private Set<Box> boxs;

    getters /setters
    ....

当我尝试保存/更新(我正在使用合并方法)代理端的数据时，我看到数据已插入但立即被删除。

我不明白为什么。这是 hibernate 的输出:

Hibernate: 
    insert 
    into
        box_user
        (role, boxid, userid) 
    values
        (?, ?, ?)
2015-05-20 15:14:23.818 TRACE: org.hibernate.type.EnumType - Binding [ADMIN_BOX] to parameter: [1]
2015-05-20 15:14:23.819 TRACE: org.hibernate.type.descriptor.sql.BasicBinder - binding parameter [2] as [BIGINT] - [1]
2015-05-20 15:14:23.819 TRACE: org.hibernate.type.descriptor.sql.BasicBinder - binding parameter [3] as [BIGINT] - [4]
Hibernate: 
    delete 
    from
        box_user 
    where
        userid=?
2015-05-20 15:14:23.831 TRACE: org.hibernate.type.descriptor.sql.BasicBinder - binding parameter [1] as [BIGINT] - [4]

这里是进行同步的方法:

private void synchroUser(Box internalBox, Long boxId)
{

    RestTemplate restTemplate = new RestTemplate();
    restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
    BoxUser[] remoteBUList = restTemplate.getForObject(DOMITIK_URL + RestURIConstant.DOMITIK_WS + "getboxuserbyboxid/{boxid}" ,BoxUser[].class,boxId);
    if(internalBox == null)
    {
        boolean firstAdd = true;
        for (BoxUser curBoxUser : remoteBUList)
        {
            // this avoid to save more than one time the box (exception occurred if trying to save several time.
            if(!firstAdd)
                curBoxUser.setBox(null);

            boxUserService.mergeElement(curBoxUser);
            firstAdd = false;
        }
    }
    else
    {
        List<BoxUser> localBUList = boxUserService.findAll();

        //deleting users that were removed from server  
        for (BoxUser localBoxUser : localBUList)
        {
            boolean userFound = false;
            for (BoxUser remoteBoxUser : remoteBUList)
            {
                if(localBoxUser.getUser().getId() == remoteBoxUser.getUser().getId())
                {
                    userFound = true;
                    break;
                }
            }

            if(!userFound)
                userService.deleteElement(localBoxUser.getUser());
        }

        //adding new users
        for (BoxUser curBoxUser : remoteBUList)
        {
            boolean userFound = false;
            for (BoxUser localBoxUser : internalBox.getBoxUsers())
            {
                if(localBoxUser.getUser().getId() == curBoxUser.getUser().getId())
                {
                    userFound = true;
                    break;
                }
            }

            if(!userFound)
            {
                curBoxUser.setBox(null);
                boxUserService.mergeElement(curBoxUser);
            }
        }

    }
}

我真的卡住了，需要明白我做错了什么......

感谢您的时间和帮助

Answer 1

我猜在你的配置中你有属性hbm2ddl.auto，其值为“create-drop”，它会在 session 结束后自动删除数据并删除模式