hibernate - Hibernate 事件监听器如何使用 HQL(命名查询)进行操作？

Question

我创建了很多 hibernate 事件监听器，以捕获所有数据库事件，如加载、持久化、更新、删除等。所有事件都会被捕获，但命名查询不会被我的加载事件监听器捕获，我想问，我需要实现什么来捕获名称查询？

Answer 1

基本上，事件的参与取决于事件(监听器)的类型和获取数据的方式。尽管您是对的，但实际上使用实体查询(EntityManager.find...、Session.load...)和使用 HQL 查询之间显然存在差异。但是在 HQL 的情况下，HQL 查询是用作命名查询还是用作常规查询并不重要。

为了展示这一点，我使用 Spring Boot、Spring Data JPA 和 Hibernate 创建了一个小示例，因为使用这种组合很容易。效果类似于使用 Hibernate 的其他应用程序架构。

如果我们使用加载事件为例，如果您使用 EntityManager.find/Session.load 接收实体，则直接加载的实体只会传播 LoadEvent 类型的事件。使用 HQL(使用 Spring Data JPA 或纯 Hibernate)，如果可疑实体作为关联间接获取，则只有这种特定类型的事件。与此相反，在所有情况下都会触发 PostLoadEvents。

这里有一些简单的类来尝试这个。

InterceptionByEventCandidate(我们要拦截的实体):

package com.example.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class InterceptionByEventCandidate {

    public static final String FETCH_ALL_QUERY = "SELECT c FROM InterceptionByEventCandidate c";
    public static final String FETCH_ALL_NAMED_QUERY = "selectAll";

    @Id
    @GeneratedValue
    private long id;

    private boolean interceptedOnLoad;

    private boolean interceptedOnPostLoad;

    public long getId() {
        return id;
    }

    public boolean isInterceptedOnLoad() {
        return interceptedOnLoad;
    }

    public void setInterceptedOnLoad(boolean interceptedOnLoad) {
        this.interceptedOnLoad = interceptedOnLoad;
    }

    public boolean isInterceptedOnPostLoad() {
        return interceptedOnPostLoad;
    }

    public void setInterceptedOnPostLoad(boolean interceptedOnPostLoad) {
        this.interceptedOnPostLoad = interceptedOnPostLoad;
    }

}

CandidateHost(需要主机来演示关联获取):

package com.example.model;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;

@Entity
public class CandidateHost {

    public static final String FETCH_ALL_QUERY = "SELECT h FROM CandidateHost h JOIN h.candidate c";
    public static final String FETCH_ALL_NAMED_QUERY = "selectAllHosts";

    @Id
    @GeneratedValue
    private long id;

    @OneToOne(cascade = CascadeType.PERSIST)
    private InterceptionByEventCandidate candidate;

    public InterceptionByEventCandidate getCandidate() {
        return candidate;
    }

    public void setCandidate(InterceptionByEventCandidate candidate) {
        this.candidate = candidate;
    }

}

现在我们需要一个合适的监听器，为了方便起见，我们将上述两种类型的事件组合在一个 HqlEventListener 中:

package com.example.event;

import org.hibernate.HibernateException;
import org.hibernate.event.spi.LoadEvent;
import org.hibernate.event.spi.LoadEventListener;
import org.hibernate.event.spi.PostLoadEvent;
import org.hibernate.event.spi.PostLoadEventListener;
import org.springframework.stereotype.Component;

import com.example.model.InterceptionByEventCandidate;

@Component
public class HqlEventListener implements LoadEventListener, PostLoadEventListener {

    private static final long serialVersionUID = -7248393324424903264L;

    @Override
    public void onLoad(LoadEvent event, LoadType loadType) throws HibernateException {
        final Object object = event.getResult();
        if (object instanceof InterceptionByEventCandidate) {
            ((InterceptionByEventCandidate) object).setInterceptedOnLoad(true);
        }
    }

    @Override
    public void onPostLoad(PostLoadEvent event) {
        final Object object = event.getEntity();
        if (object instanceof InterceptionByEventCandidate) {
            ((InterceptionByEventCandidate) object).setInterceptedOnPostLoad(true);
        }
    }

}

要告诉 Hibernate 我们要处理哪些事件，我们需要一些配置:

package com.example.event;

import javax.annotation.PostConstruct;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;

import org.hibernate.event.service.spi.EventListenerRegistry;
import org.hibernate.event.spi.EventType;
import org.hibernate.internal.SessionFactoryImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;

@Configuration
public class EntityListenerConfiguration {

    @PersistenceUnit
    private EntityManagerFactory entityManagerFactory;

    @Autowired
    private HqlEventListener hqlEventListener;

    @PostConstruct
    protected void init() {
        final SessionFactoryImpl sessionFactory = entityManagerFactory.unwrap(SessionFactoryImpl.class);
        final EventListenerRegistry eventListenerRegistry = sessionFactory.getServiceRegistry()
                .getService(EventListenerRegistry.class);

        eventListenerRegistry.getEventListenerGroup(EventType.LOAD).appendListener(hqlEventListener);
        eventListenerRegistry.getEventListenerGroup(EventType.POST_LOAD).appendListener(hqlEventListener);

    }
}

为了提供和重用命名查询，我们将其存储在包信息文件中:

@NamedQueries({
        @NamedQuery(name = InterceptionByEventCandidate.FETCH_ALL_NAMED_QUERY, query = InterceptionByEventCandidate.FETCH_ALL_QUERY),
        @NamedQuery(name = CandidateHost.FETCH_ALL_NAMED_QUERY, query = CandidateHost.FETCH_ALL_QUERY) })

package com.example.event;

import org.hibernate.annotations.NamedQueries;
import org.hibernate.annotations.NamedQuery;

import com.example.model.CandidateHost;
import com.example.model.InterceptionByEventCandidate;

当然，如果它们表现出相同的行为，则需要一些 Spring Data JPA 存储库进行尝试。

InterceptionByEventCandidateRepository:

package com.example.repository;

import java.util.Set;

import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import com.example.model.InterceptionByEventCandidate;

@Repository
public interface InterceptionByEventCandidateRepository extends CrudRepository<InterceptionByEventCandidate, Long> {

    @Query(InterceptionByEventCandidate.FETCH_ALL_QUERY)
    @Transactional(readOnly = true)
    Set<InterceptionByEventCandidate> findByHQL();

    @Query(name = InterceptionByEventCandidate.FETCH_ALL_NAMED_QUERY)
    @Transactional(readOnly = true)
    Set<InterceptionByEventCandidate> findByNamedHQL();
}

候选主机库:

package com.example.repository;

import java.util.Set;

import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import com.example.model.CandidateHost;

@Repository
public interface CandidateHostRepository extends CrudRepository<CandidateHost, Long> {

    @Query(CandidateHost.FETCH_ALL_QUERY)
    @Transactional(readOnly = true)
    Set<CandidateHost> findByHQL();

    @Query(name = CandidateHost.FETCH_ALL_NAMED_QUERY)
    @Transactional(readOnly = true)
    Set<CandidateHost> findByNamedHQL();

}

那是很多示例代码，这里是一个(我不得不承认也是巨大的)测试来检查策略之间的事件差异:

package com.example.repository;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import java.util.Set;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.hibernate.Query;
import org.hibernate.Session;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.transaction.annotation.Transactional;

import com.example.model.CandidateHost;
import com.example.model.InterceptionByEventCandidate;

@RunWith(SpringRunner.class)
@Transactional
@SpringBootTest
public class HqlEventTests {

    @Autowired
    private CandidateHostRepository candidateHostRepository;

    @Autowired
    private InterceptionByEventCandidateRepository interceptionByEventCandidateRepository;

    @PersistenceContext
    private EntityManager entityManager;

    @Before
    public void setUp() {
        final CandidateHost host = new CandidateHost();
        final InterceptionByEventCandidate interceptionByEventCandidate = new InterceptionByEventCandidate();
        host.setCandidate(interceptionByEventCandidate);
        candidateHostRepository.save(host);
        entityManager.flush();
        entityManager.clear();
    }

    @Test
    public void interceptCandidateAtFindingHostBySpringDataJpaHql() {
        final Set<CandidateHost> result = candidateHostRepository.findByHQL();
        verifyInterceptions(result.stream().findFirst().get().getCandidate(), true, true);
    }

    @Test
    public void interceptCandidateAtFindingHostBySpringDataJpaNamedHql() {
        final Set<CandidateHost> result = candidateHostRepository.findByNamedHQL();
        verifyInterceptions(result.stream().findFirst().get().getCandidate(), true, true);
    }

    @Test
    public void interceptCandidateAtFindingHostByHibernateHql() {
        final Session session = entityManager.unwrap(Session.class);
        final Query query = session.createQuery(CandidateHost.FETCH_ALL_QUERY);

        verifyInterceptions(((CandidateHost) query.list().stream().findFirst().get()).getCandidate(), true, true);
    }

    @Test
    public void interceptCandidateAtFindingHostByHibernateNamedHql() {
        final Session session = entityManager.unwrap(Session.class);
        final Query query = session.getNamedQuery(CandidateHost.FETCH_ALL_NAMED_QUERY);

        verifyInterceptions(((CandidateHost) query.list().stream().findFirst().get()).getCandidate(), true, true);
    }

    @Test
    public void interceptCandidateBySpringDataJpaHql() {
        final Set<InterceptionByEventCandidate> result = interceptionByEventCandidateRepository.findByHQL();
        verifyInterceptions(result.stream().findFirst().get(), false, true);
    }

    @Test
    public void interceptCandidateBySpringDataJpaNamedHql() {
        final Set<InterceptionByEventCandidate> result = interceptionByEventCandidateRepository.findByNamedHQL();
        verifyInterceptions(result.stream().findFirst().get(), false, true);
    }

    @Test
    public void interceptCandidateByHibernateHql() {
        final Session session = entityManager.unwrap(Session.class);
        final Query query = session.createQuery(InterceptionByEventCandidate.FETCH_ALL_QUERY);

        verifyInterceptions((InterceptionByEventCandidate) query.list().stream().findFirst().get(), false, true);
    }

    @Test
    public void interceptCandidateByHibernateNamedHql() {
        final Session session = entityManager.unwrap(Session.class);
        final Query query = session.getNamedQuery(InterceptionByEventCandidate.FETCH_ALL_NAMED_QUERY);

        verifyInterceptions((InterceptionByEventCandidate) query.list().stream().findFirst().get(), false, true);
    }

    @Test
    public void interceptCandidateByHibernateFind() {
        long id = interceptionByEventCandidateRepository.findAll().iterator().next().getId();

        entityManager.flush();
        entityManager.clear();

        final Session session = entityManager.unwrap(Session.class);
        final InterceptionByEventCandidate candidate = session.load(InterceptionByEventCandidate.class, id);
        verifyInterceptions(candidate, true, true);
    }

    private void verifyInterceptions(final InterceptionByEventCandidate candidate, final boolean expectedLoadEventState,
            final boolean expectedPostLoadEventState) {
        assertThat("Expected load state did not match!", candidate.isInterceptedOnLoad(), is(expectedLoadEventState));
        assertThat("Expected postload state did not match!", candidate.isInterceptedOnPostLoad(),
                is(expectedPostLoadEventState));
    }
}

查看此测试，我们可以看到命名查询和常规查询之间没有区别。如果您担心其他类型的事件，我想扩展它很容易。