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 >