使用Spring Data JPA查找实体时如何启用LockModeType.PESSIMISTIC_WRITE? [英] How to enable LockModeType.PESSIMISTIC_WRITE when looking up entities with Spring Data JPA?

问题描述

我该如何实现与以下代码等效的功能:

How can I achieve the equivalent of this code:

tx.begin();
Widget w = em.find(Widget.class, 1L, LockModeType.PESSIMISTIC_WRITE);
w.decrementBy(4);
em.flush();
tx.commit();

...但是使用Spring和Spring-Data-JPA批注?

... but using Spring and Spring-Data-JPA annotations?

我现有代码的基础是:

@Service
@Transactional(readOnly = true)
public class WidgetServiceImpl implements WidgetService
{
  /** The spring-data widget repository which extends CrudRepository<Widget, Long>. */
  @Autowired
  private WidgetRepository repo;

  @Transactional(readOnly = false)
  public void updateWidgetStock(Long id, int count)
  {
    Widget w = this.repo.findOne(id);
    w.decrementBy(4);
    this.repo.save(w);
  }
}

但是我不知道如何指定updateWidgetStock方法中的所有操作都应使用悲观锁设置.

But I don't know how to specify that everything in the updateWidgetStock method should be done with a pessimistic lock set.

有一个Spring Data JPA批注org.springframework.data.jpa.repository.Lock，它允许您设置LockModeType，但是我不知道将其放在updateWidgetStock方法上是否有效.听起来更像是WidgetRepository上的注释，因为Javadoc说:

There is a Spring Data JPA annotation org.springframework.data.jpa.repository.Lock which allows you to set a LockModeType, but I don't know if it's valid to put it on the updateWidgetStock method. It sounds more like an annotation on the WidgetRepository, because the Javadoc says:

org.springframework.data.jpa.repository
@Target(value = METHOD)
@Retention(value = RUNTIME)
@Documented
public @interface锁
用于指定执行查询时要使用的LockModeType的注释.在查询方法上使用Query或从方法名称派生查询时，将对它进行评估.

org.springframework.data.jpa.repository
@Target(value=METHOD)
@Retention(value=RUNTIME)
@Documented
public @interface Lock
Annotation used to specify the LockModeType to be used when executing the query. It will be evaluated when using Query on a query method or if you derive the query from the method name.

...所以似乎没有帮助.

... so that doesn't seem to be helpful.

如何在设置了LockModeType.PESSIMISTIC_WRITE的情况下执行我的updateWidgetStock()方法?

How can I make my updateWidgetStock() method execute with LockModeType.PESSIMISTIC_WRITE set?

推荐答案

@Lock(实际上，已经有一个门票.

@Lock is supported on CRUD methods as of version 1.6 of Spring Data JPA (in fact, there's already a milestone available). See this ticket for more details.

使用该版本，您只需声明以下内容:

With that version you simply declare the following:

interface WidgetRepository extends Repository<Widget, Long> {

  @Lock(LockModeType.PESSIMISTIC_WRITE)
  Widget findOne(Long id);
}

这将导致后备存储库代理的CRUD实现部分将配置的LockModeType应用于EntityManager上的find(…)调用.

This will cause the CRUD implementation part of the backing repository proxy to apply the configured LockModeType to the find(…) call on the EntityManager.

这篇关于使用Spring Data JPA查找实体时如何启用LockModeType.PESSIMISTIC_WRITE?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！