hibernate的Criteria的一个bug

 

这个bug是在使用hibernate annotation过程中发现的，开始以为是hibenrate annotation的bug，后来又使用xml文件来配置，还是存在同样的问题。
问题场景：我需要使用省份与城市，他们的关系是：一个省有个多城市，很简单的OneToMany关系，在改变province中的cities的lazy特性时，遇到问题
由于我采用把所有的资源都是放在一个表中的策略，所有这里有一个基类Resource

基类

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "CATEGORY_ID", discriminatorType = DiscriminatorType.STRING)
@Table(name = "T_RESOURCE")
public class Resource implements Serializable ...{

    private String id;

    private String name;

    private ResourceCategory resourceCategory;

    @Id
    @GenericGenerator(name = "generator", strategy = "uuid")
    @GeneratedValue(generator = "generator")
    @Column(name = "ID")
    public String getId() ...{
        return id;
    }

    @Column(name = "NAME")
    public String getName() ...{
        return name;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "CATEGORY_ID", updatable = false, insertable = false)
    public ResourceCategory getResourceCategory() ...{
        return resourceCategory;
    }

    @Override
    public boolean equals(final Object other) ...{
        if (!(other instanceof Resource))
            return false;
        Resource castOther = (Resource) other;
        return new EqualsBuilder().append(id, castOther.id).isEquals();
    }

    @Override
    public int hashCode() ...{
        return new HashCodeBuilder().append(id).toHashCode();
    }
}

Province子类

@Entity
@DiscriminatorValue("province")
public class Province extends Resource ...{

    private Set<City> cities = new HashSet<City>();

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "province")
    public Set<City> getCities() ...{
        return cities;
    }
}

 子类City

@Entity
@DiscriminatorValue("city")
public class City extends Resource ...{
    private Province province;

    public City(String name, ResourceCategory resourceCategory) ...{
        super(name, resourceCategory);
    }

    @ManyToOne
    @JoinColumn(name = "PARENT_ID")
    public Province getProvince() ...{
        return province;
    }
}

 hibernate.cfg.xml

<!-- 
    <mapping resource="ResourceCategory.hbm.xml" />
    <mapping resource="Resource.hbm.xml" />
-->
<mapping class="ResourceCategory" />
<mapping class="Resource" />

hibernate助手类

public class HibernateUtil ...{

    private static SessionFactory sessionFactory;

    static ...{
        // Configuration configuration = new Configuration();
        AnnotationConfiguration configuration = new AnnotationConfiguration();
        configuration.configure();

        sessionFactory = configuration.buildSessionFactory();
    }

    public static SessionFactory getSessionFactory() ...{
        return sessionFactory;
    }

    public Session getSession() ...{
        return getSessionFactory().openSession();
    }
}

单元测试类

public class HibnerateTest extends TestCase ...{

    public void testListProvinceByHQL() ...{
        SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction ctx = session.beginTransaction();

        Query query = session.createQuery("from Province");
        List<Province> provinces = query.list();

        for (Province province : provinces) ...{
            System.out.println(province.getName());
        }

        ctx.commit();
    }

    public void testListProvinceByCriteria() ...{
        SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction ctx = session.beginTransaction();

        Criteria criteria = session.createCriteria(Province.class);
        
        List<Province> provinces = criteria.list();

        for (Province province : provinces) ...{
            System.out.println(province.getName());
        }

        ctx.commit();
    }
}

分别执行单元测试方法，他们输出的sql语句是一样的，但是输出的结果是不一样的。
select this_.ID as ID1_1_, this_.NAME as NAME1_1_, this_.COMMENTS as COMMENTS1_1_, this_.CATEGORY_ID as CATEGORY2_1_1_, cities2_.PARENT_ID as PARENT5_3_, cities2_.ID as ID3_, cities2_.ID as ID1_0_, cities2_.NAME as NAME1_0_, cities2_.COMMENTS as COMMENTS1_0_, cities2_.CATEGORY_ID as CATEGORY2_1_0_, cities2_.PARENT_ID as PARENT5_1_0_ from T_RESOURCE this_ left outer join T_RESOURCE cities2_ on this_.ID=cities2_.PARENT_ID where this_.CATEGORY_ID='province'
testListProvinceByHQL方式输出的是
上海
上海
上海
上海
江苏
江苏
江苏
江苏

testListProvinceByCriteria方式输出的是
上海
江苏

若把public Set<City> getCities()的映射改为
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "province")
    @Fetch(FetchMode.SELECT)
或者
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "province")
    @LazyCollection(LazyCollectionOption.FALSE)

则两个方法输出sql语句是一样的，且结果也一样
SQL:
select this_.ID as ID1_0_, this_.COMMENTS as COMMENTS1_0_, this_.NAME as NAME1_0_, this_.CATEGORY_ID as CATEGORY1_1_0_ from T_RESOURCE this_ where this_.CATEGORY_ID='province'
select cities0_.PARENT_ID as PARENT5_1_, cities0_.ID as ID1_, cities0_.ID as ID1_0_, cities0_.COMMENTS as COMMENTS1_0_, cities0_.NAME as NAME1_0_, cities0_.CATEGORY_ID as CATEGORY1_1_0_, cities0_.PARENT_ID as PARENT5_1_0_ from T_RESOURCE cities0_ where cities0_.PARENT_ID=?
select cities0_.PARENT_ID as PARENT5_1_, cities0_.ID as ID1_, cities0_.ID as ID1_0_, cities0_.COMMENTS as COMMENTS1_0_, cities0_.NAME as NAME1_0_, cities0_.CATEGORY_ID as CATEGORY1_1_0_, cities0_.PARENT_ID as PARENT5_1_0_ from T_RESOURCE cities0_ where cities0_.PARENT_ID=?
输出：
上海
江苏

从上面的现象可是看出，不论配置文件怎么变化，通过hql语句获得结果一直不变，而Criteria会变化，这就证明了Criteria是有bug的。
据此我得出结论:hibernate的Criteria在把关联的lazy属性设置为"false"，且把fetch设置为join时，查找数据就存在bug

后来我使用xml配置文件的方式，也存在同样的问题，也证明了我的这个结论，

Resource.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="Resource"
        table="T_RESOURCE">

        <id name="id" type="string">
            <column name="ID" />
        </id>

        <discriminator column="CATEGORY_ID" type="string" />

        <property name="name" type="string" column="NAME" />

        <many-to-one name="resourceCategory" insert="false"
            update="false"
            class="ResourceCategory"
            column="CATEGORY_ID" />

        <subclass name="Province"
            discriminator-value="province">
            <set name="cities" lazy="false" fetch="join">
                <key>
                    <column name="PARENT_ID" />
                </key>
                <one-to-many class="City" />
            </set>
        </subclass>

        <subclass name="City"
            discriminator-value="city">
            <many-to-one name="province"
                class="Province"
                column="PARENT_ID" />
        </subclass>

    </class>
</hibernate-mapping>

ResourceCategory.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="ResourceCategory"
        table="T_RESOURCE_CATEGORY">

        <id name="id" type="string">
            <column name="ID" />
        </id>

        <property name="name" type="string" column="NAME" />

    </class>
</hibernate-mapping>