JPA 2 Criteria API - 使用 Eclipselink 将 JPQL 转换为 Criteria API 查询时出现异常

Question

我在将 JPA 查询转换为使用 Criteria API 时遇到问题

我有以下查询，尝试查找与传递的地址参数匹配的 ServiceUser。 ServiceUser 是一个抽象实体，具有具体的子类 Child 和 Adult。我在 ServiceUser 类上使用联合继承策略。

当我调用这个方法时一切正常。

public Set<T> findByAddress(Address address) {

    Query query = manager.createQuery("SELECT distinct s FROM ServiceUser AS s JOIN s.addressHistory as h where h = :address");
    query.setParameter("address", address);

    HashSet<T> result = new HashSet<T>();
    for (Object s : query.getResultList()) {
        // tClass is the runtime type of the generic session bean.
        if (this.tClass.isInstance(s)) {
            result.add((T) s);
        }
    }

     return result;
}

但是，如果我尝试用以下使用生成的元模型和类型化查询的函数替换该函数，那么我会收到一个异常，

public Set<T> findByAddress(Address address) {

    CriteriaBuilder cb = manager.getCriteriaBuilder();
    CriteriaQuery<ServiceUser> cq = cb.createQuery(ServiceUser.class);
    Root<ServiceUser> su = cq.from(ServiceUser.class);

    Join<ServiceUser, Address> addressHistory = su.join(ServiceUser_.addressHistory);
    cq.select(su).distinct(true).where(cb.equal(addressHistory, cb.parameter(Address.class, "address")));
    TypedQuery<ServiceUser> q = manager.createQuery(cq);
    q.setParameter("address", address);

    HashSet<T> result = new HashSet<T>();
    for (ServiceUser s : q.getResultList()) {
        // tClass is the runtime type of the generic session bean.
        if (this.tClass.isInstance(s)) {
            result.add((T) s);
        }
    }

    return result;
}

这是 Eclipslink 日志记录的堆栈跟踪。似乎抛出了 NulPointerException 但我不确定为什么？

 /**
Test : shouldBeAbleToFindChildByAddress()
uk.gov.sunderland.ccms.model.bean.ChildService.findByAddress(Address[id=1,lineOne=7,lineTwo=Camberwell Way,lineThree=Moorside,lineFour=Sunderland,postcode=SR7 3XN])
[EL Finer]: 2010-12-20 12:39:42.89--ServerSession(7055953)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--client acquired
[EL Finer]: 2010-12-20 12:39:42.89--UnitOfWork(22763294)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--TX binding to tx mgr, status=STATUS_ACTIVE
[EL Finest]: 2010-12-20 12:39:42.89--UnitOfWork(22763294)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--Execute query ReadObjectQuery(referenceClass=Address sql="SELECT ID, LINE_TWO, LINE_THREE, LINE_ONE, LINE_FOUR, POSTCODE FROM ADDRESS WHERE (ID = ?)")
[EL Finest]: 2010-12-20 12:39:42.906--UnitOfWork(22763294)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--Execute query ReadAllQuery(referenceClass=ServiceUser )
[EL Finest]: 2010-12-20 12:39:42.906--ServerSession(7055953)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--reconnecting to external connection pool
[EL Fine]: 2010-12-20 12:39:42.906--ServerSession(7055953)--Connection(32184426)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--SELECT DISTINCT t2.SERVICE_USER_TYPE FROM ADDRESS t0, SERVICE_USER t2, SERVICE_USER_ADDRESS t1 WHERE ((? = t0.ID) AND ((t1.SERVICE_USER_ID = t2.ID) AND (t0.ID = t1.ADDRESS_ID)))
        bind => [1]
[EL Finer]: 2010-12-20 12:39:42.906--UnitOfWork(22763294)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--class uk.gov.sunderland.ccms.model.entity.Adult
[EL Finest]: 2010-12-20 12:39:42.906--ServerSession(7055953)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--reconnecting to external connection pool
[EL Fine]: 2010-12-20 12:39:42.906--ServerSession(7055953)--Connection(29495316)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--SELECT DISTINCT t0.ID, t0.SERVICE_USER_TYPE, t0.TITLE, t0.DOB, t0.GENDER, t0.DISABILITY, t0.ETHNICITY, t1.ID, t1.EMPLOYMENT, t1.INFO_PACK_REQUIRED, t1.HOME_PHONE, t1.OTHER_LANGUAGE, t1.REFERRER, t1.MOBILE_PHONE, t1.LONE_PARENT, t1.GP_PRACTICE, t1.CONTACTABLE, t1.WORK_PHONE, t1.BABY_DUE_DATE, t1.ENGLISH_LEVEL FROM SERVICE_USER_ADDRESS t3, ADDRESS t2, ADULT t1, SERVICE_USER t0 WHERE (((? = t2.ID) AND ((t1.ID = t0.ID) AND (t0.SERVICE_USER_TYPE = ?))) AND ((t3.SERVICE_USER_ID = t0.ID) AND (t2.ID = t3.ADDRESS_ID)))
        bind => [1, 1]
[EL Warning]: 2010-12-20 12:39:42.906--UnitOfWork(22763294)--Thread(Thread[pool-52-thread-1,5,grizzly-kernel])--java.lang.NullPointerException
        at org.eclipse.persistence.descriptors.InheritancePolicy.selectAllRowUsingDefaultMultipleTableSubclassRead(InheritancePolicy.java:1355)
        at org.eclipse.persistence.descriptors.InheritancePolicy.selectAllRowUsingMultipleTableSubclassRead(InheritancePolicy.java:1396)
        at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2493)
        at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:407)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1074)
        at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:736)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1034)
        at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:380)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1112)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2909)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1291)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1273)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1247)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.executeReadQuery(EJBQueryImpl.java:479)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getResultList(EJBQueryImpl.java:714)
*/

查看使用失败条件 api 查询发出的 sql，并与使用 jpa 字符串查询执行查询时发出的 sql 进行比较。

条件查询

   SELECT DISTINCT t0.ID, t0.SERVICE_USER_TYPE, t0.TITLE, t0.DOB, t0.GENDER, t0.DISABILITY, t0.ETHNICITY, t1.ID, t1.EMPLOYMENT, t1.INFO_PACK_REQUIRED, t1.HOME_PHONE, t1.OTHER_LANGUAGE, t1.REFERRER, t1.MOBILE_PHONE, t1.LONE_PARENT, t1.GP_PRACTICE, t1.CONTACTABLE, t1.WORK_PHONE, t1.BABY_DUE_DATE, t1.ENGLISH_LEVEL 
FROM SERVICE_USER_ADDRESS t3, ADDRESS t2, ADULT t1, SERVICE_USER t0 
WHERE (((? = t2.ID) AND ((t1.ID = t0.ID) AND (t0.SERVICE_USER_TYPE = ?))) 
AND ((t3.SERVICE_USER_ID = t0.ID) AND (t2.ID = t3.ADDRESS_ID)))

JPA 字符串查询

  SELECT DISTINCT t0.ID, t0.SERVICE_USER_TYPE, t0.TITLE, t0.DOB, t0.GENDER, t0.DISABILITY, t0.ETHNICITY, t1.ID, t1.EMPLOYMENT, t1.INFO_PACK_REQUIRED, t1.HOME_PHONE, t1.OTHER_LANGUAGE, t1.REFERRER, t1.MOBILE_PHONE, t1.LONE_PARENT, t1.GP_PRACTICE, t1.CONTACTABLE, t1.WORK_PHONE, t1.BABY_DUE_DATE, t1.ENGLISH_LEVEL
FROM SERVICE_USER_ADDRESS t3, ADDRESS t2, ADULT t1, SERVICE_USER t0 
WHERE (((? = t2.ID) AND ((t1.ID = t0.ID) AND (t0.SERVICE_USER_TYPE = ?))) 
AND ((t3.SERVICE_USER_ID = t0.ID) AND (t2.ID = t3.ADDRESS_ID)))

，

SELECT DISTINCT t0.ID, t0.SERVICE_USER_TYPE, t0.TITLE, t0.DOB, t0.GENDER, t0.DISABILITY, t0.ETHNICITY, t1.ID 
FROM SERVICE_USER_ADDRESS t3, ADDRESS t2, CHILD t1, SERVICE_USER t0 WHERE (((? = t2.ID) AND ((t1.ID = t0.ID) AND (t0.SERVICE_USER_TYPE = ?))) AND ((t3.SERVICE_USER_ID = t0.ID) AND (t2.ID = t3.ADDRESS_ID)))

我可以看到处理 ServiceUser 的 Adult 子类的第一部分在两种情况下都是相同的，但是当涉及到 Child 子类时，Criteria查询抛出

 [EL Warning]: 2010-12-20 )--java.lang.NullPointerException
        at org.eclipse.persistence.descriptors.InheritancePolicy.selectAllRowUsingDefaultMultipleTableSubclassRead(InheritancePolicy.java:1355)

这可能是 Eclipselink 的错误吗？

Answer 1

是的，这确实似乎是 Eclipselink 的一个错误，

 <dependency>
     <groupId>org.eclipse.persistence</groupId>
     <artifactId>eclipselink</artifactId>
     <version>2.1.1</version>
     <scope>provided</scope>
 </dependency>

继承策略从 更改为

@Inheritance(strategy = InheritanceType.JOINED)

提供了一种解决方法，在我的情况下是可以的。

@Inheritance(strategy = InheritanceType.SINGLE_TABLE)

将抽象基类 SERVICE_USER 的