Question

我有一个用@Service注释的类正在实现javax.jms.MessageListener，在onMessage函数中我正在从存储库中检索一个对象，但是当我尝试预加载延迟加载的属性时，我得到“无法初始化代理 - 没有会话“例外。

我不想禁用延迟加载，因为页面实体在很多子实体中变得非常大，并且大多数时候我在处理页面对象时不需要这些子实体。

我在谷歌上发现并尝试了很多其他问题和解决方案，但似乎没有一个对我产生影响。

@Service
public class PageService implements MessageListener {
    private PageRepository pageRepository;
    public PageService(PageRepository pageRepository){
        this.pageRepository = pageRepository;
    }

    @Override
    @Transactional
    public void onMessage(Message message) {
        // Message handling etc etc..
        int id = ....
        Page page = pageRepository.findOne(id); // Page is retrieved successfully

        page.InitializeAll(); // <--- Error happens here

        // Build response message.
    }
}

实体：

@Entity
public class Page {
    ....

    @OrderBy("id ASC")
    @OneToMany(mappedBy = "page", cascade = CascadeType.ALL)
    public Set<Row> rows;

    public void InitializeAll(){
        Hibernate.initialize(this.rows);      // <--- Error
        rows.forEach(r -> r.InitializeAll());
    }
}

页面存储库只是扩展了CrudRepository：

public interface PageRepository extends CrudRepository<Page, Integer>

在同一个包（/ folder）中的另一个文件中我有另一个用@Transactional注释的函数，里面有相同的函数调用，这里一切正常。

@MessageMapping("/page/{id}/request")
@SendToUser(value = "/queue/private", broadcast = false)
@Transactional
public initialPageMessage subscribeClient(@DestinationVariable("id") int pageId) {
    initialPageMessage resp = new initialPageMessage();
    resp.page = pageRepository.findOne(pageId);
    resp.page.InitializeAll();
    return resp;
 }

TransactionManagerConfiguration：

@Configuration
@EnableTransactionManagement
public class TransactionManagerConfiguration {
    private EntityManagerFactory entityManagerFactory;
    private DataSource datasource;

    public TransactionManagerConfiguration(EntityManagerFactory entityManagerFactory, DataSource datasource){
        this.entityManagerFactory = entityManagerFactory;
        this.datasource = datasource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(){
        JpaTransactionManager tm = new JpaTransactionManager();
        tm.setEntityManagerFactory(entityManagerFactory);
        tm.setDataSource(datasource);
        return tm;
    }
}

堆栈跟踪

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: models.Page.rows, could not initialize proxy - no Session
    at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:587) ~[hibernate-core-5.0.11.Final.jar:5.0.11.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:204) ~[hibernate-core-5.0.11.Final.jar:5.0.11.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:566) ~[hibernate-core-5.0.11.Final.jar:5.0.11.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:739) ~[hibernate-core-5.0.11.Final.jar:5.0.11.Final]
    at org.hibernate.Hibernate.initialize(Hibernate.java:65) ~[hibernate-core-5.0.11.Final.jar:5.0.11.Final]
    at models.Page.InitializeAll(Page.java:31) ~[classes/:na]
    at controllers.PageService.processMessage(PageService.java:93) ~[classes/:na]
    at controllers.PageService.onMessage(PageService.java:75) ~[classes/:na]
    at org.apache.activemq.ActiveMQMessageConsumer.dispatch(ActiveMQMessageConsumer.java:1401) ~[activemq-client-5.14.3.jar:5.14.3]
    at org.apache.activemq.ActiveMQSessionExecutor.dispatch(ActiveMQSessionExecutor.java:131) [activemq-client-5.14.3.jar:5.14.3]
    at org.apache.activemq.ActiveMQSessionExecutor.iterate(ActiveMQSessionExecutor.java:202) [activemq-client-5.14.3.jar:5.14.3]
    at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:133) [activemq-client-5.14.3.jar:5.14.3]
    at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:48) [activemq-client-5.14.3.jar:5.14.3]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_40]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_40]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_40]

Answer 1

一段时间后，我发现了问题，问题是从同一类内部调用了“ onMessage”方法。这样可以防止@Transactional代理（包装类）被调用。当我将@Transactional移到另一个类并从该类外部调用该函数时，它开始工作。

@Transactional无效

1 个答案: