【发布时间】：2015-12-20 16:41:25
【问题描述】：
我有一个休眠多对多关系的问题：当我从我的集合中删除一个项目时，它不会在我的数据库中删除。我知道有很多类似的问题，但我没有通过阅读它们来解决我的问题。
我已经为它编写了一个 JUnit 测试用例。我的关联是在建筑物和用户之间：
@Test
public void testBuildingManyToMany(){
//Create 2 buildings
Building building = createBuilding("b1");
Building building2 = createBuilding("b2");
//Create 1 user
User user = createUser("u1");
//Associate the 2 buildings to that user
user.getBuildings().add(building);
building.getUsers().add(user);
user.getBuildings().add(building2);
building2.getUsers().add(user);
userController.save(user);
user = userController.retrieve(user.getId());
Assert.assertEquals(2, user.getBuildings().size());//Test OK
//Test 1: remove 1 building from the list
user.getBuildings().remove(building);
building.getUsers().remove(user);
userController.save(user);
//Test 2: clear and add
//user.getBuildings().clear();
//user.getBuildings().add(building);
//userController.save(user);
//user = userController.retrieve(user.getId());
//Assert.assertEquals(1, user.getBuildings().size());
}
这是我得到的错误：
...
Hibernate: insert into building_useraccount (userid, buildingid) values (?, ?)
Hibernate: insert into building_useraccount (userid, buildingid) values (?, ?)
Hibernate: delete from building_useraccount where userid=? and buildingid=?
Hibernate: insert into building_useraccount (userid, buildingid) values (?, ?)
4113 [main] WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: 23505, SQLState: 23505
4113 [main] ERROR org.hibernate.util.JDBCExceptionReporter - Unique index or primary key violation: "PRIMARY_KEY_23 ON PUBLIC.BUILDING_USERACCOUNT(BUILDINGID, USERID) VALUES ( /* key:0 */ 201, 201)"; SQL statement:
insert into building_useraccount (userid, buildingid) values (?, ?) [23505-176]
当我注释“测试 1”并取消注释“测试 2”行时，出现以下错误：
junit.framework.AssertionFailedError:
Expected :1
Actual :2
这是我的 hbm.xml 类：
<hibernate-mapping default-lazy="true">
<class name="my.model.pojo.Building" table="building">
<cache usage="read-write" />
<id name="id" column="id" type="java.lang.Long">
<generator class="sequence">
<param name="sequence">building_id_sequence</param>
</generator>
</id>
<property name="name" type="java.lang.String" column="name" not-null="true" />
...
<set name="users" cascade="none" lazy="true" inverse="true" table="building_useraccount">
<key column="buildingid" />
<many-to-many class="my.model.pojo.User" column="userid" />
</set>
</class>
</hibernate-mapping>
和
<hibernate-mapping default-lazy="true">
<class name="my.model.pojo.User" table="useraccount">
<cache usage="read-write" />
<id name="id" column="id" type="java.lang.Long">
<generator class="sequence">
<param name="sequence">useraccount_id_sequence</param>
</generator>
</id>
<property name="login" type="java.lang.String" column="login" not-null="true" unique="true" length="40" />
...
<set name="buildings" cascade="none" lazy="false" fetch="join" table="building_useraccount">
<key column="userid" />
<many-to-many class="my.model.pojo.Building" column="buildingid" />
</set>
</class>
</hibernate-mapping>
类
public class User implements Serializable, Identifiable {
private static final long serialVersionUID = 1L;
private int hashCode;
private Long id;
private String login;
private Set<Building> buildings = new HashSet<Building>();
public boolean equals(Object value) {
if (value == this)
return true;
if (value == null || !(value instanceof User))
return false;
if (getId() != null && getId().equals(((User) value).getId()))
return true;
return super.equals(value);
}
public int hashCode() {
if (hashCode == 0) {
hashCode = (getId() == null) ? super.hashCode() : new HashCodeBuilder().append(getId()).toHashCode();
}
return hashCode;
}
/* Getter / Setter ... */
和
public class BuildingBase implements Serializable, Identifiable {
private static final long serialVersionUID = 1L;
private int hashCode;
private Long id;
private String name;
private Set<User> users = new HashSet<User>();
public boolean equals(Object value) {
if (value == this)
return true;
if (value == null || !(value instanceof Building))
return false;
if (getId() != null && getId().equals(((Building) value).getId()))
return true;
return super.equals(value);
}
public int hashCode() {
if (hashCode == 0) {
hashCode = (getId() == null) ? super.hashCode() : new HashCodeBuilder().append(getId()).toHashCode();
}
return hashCode;
}
/* Getter / Setter ... */
编辑：为事务添加 userController 实现
@Transactional(readOnly = false, propagation = Propagation.REQUIRED)
public User save(User user) throws ServiceException {
validate(user);//Validation stuffs
return userDAO.update(user);
}
用户DAO：
public class UserDAOImpl extends HibernateDAOImpl<User> implements UserDAO {
}
还有 HibernateDAOImpl：
public class HibernateDAOImpl<T> implements DAO<T> {
public T update(T entity) {
return executeAndCreateSessionIfNeeded(new HibernateAction<T>() {
@Override
public T execute(Session session) {
return (T) session.merge(entity);
}
});
}
protected <E> E executeAndCreateSessionIfNeeded(HibernateAction<E> action) {
Session session = null;
try {
session = sessionFactory.getCurrentSession();
return executeAction(action, session);
} finally {
if (session != null) {
session.close();
}
}
}
}
【问题讨论】：
-
请贴出
userController.save方法的实现。另外，事务边界是什么？ -
我添加了一些实现。该事务运行良好，因为它成功地在代码中的任何地方使用。另请注意，清除建筑物（使用 user.getBuildings().clear()）也可以并清空我的多对多数据库表！只是移除奇怪地不起作用......
标签： java hibernate orm many-to-many hibernate-mapping