java 自动提交和@Transactional 以及带有 spring、jpa 和 hibernate 的级联

autocommit and @Transactional and Cascading with spring, jpa and hibernate

提问by subes

what I would like to accomplish is the following:

我想完成的是以下内容：

1. have autocommit enabled so per default all queries get commited
2. if there is a @Transactional on a method, it overrides the autocommit and encloses all queries into a single transaction, thus overriding the autocommit
3. if there is a @Transactional method that calls other @Transactional annotated methods, the outer most annotation should override the inner annotaions and create a larger transaction, thus annotations also override eachother

1. 启用自动提交，因此默认情况下所有查询都会提交
2. 如果方法上有@Transactional，它会覆盖自动提交并将所有查询包含在一个事务中，从而覆盖自动提交
3. 如果有一个@Transactional 方法调用其他@Transactional 注解的方法，最外层的注解应该覆盖内部的注解并创建一个更大的事务，因此注解也会相互覆盖

I am currently still learning about spring-orm and couldn't find documentation about this and don't have a test project for this yet.

我目前仍在学习 spring-orm 并且找不到关于此的文档，并且还没有针对此的测试项目。

So my questions are:

所以我的问题是：

• What is the default behaviour of transactions in spring?
• If the default differs from my requirement, is there a way to configure my desired behaviour?
• Or is there a totally different best practice for transactions?

• spring中事务的默认行为是什么？
• 如果默认值与我的要求不同，有没有办法配置我想要的行为？
• 或者是否有完全不同的交易最佳实践？

--EDIT--

- 编辑 -

I have the following test-setup:

我有以下测试设置：

@javax.persistence.Entity
public class Entity {
  @Id
  @GeneratedValue
  private Integer id;
  private String name;
  public Integer getId() {
    return id;
  }
  public void setId(Integer id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}

@Repository
public class Dao {
  @PersistenceContext
  private EntityManager em;
  public void insert(Entity ent) {
    em.persist(ent);
  }
  @SuppressWarnings("unchecked")
  public List<Entity> selectAll() {
    List<Entity> ents = em.createQuery("select e from " + Entity.class.getName() + " e").getResultList();
    return ents;
  }
}

If I have it like this, even with autocommit enabled in hibernate, the insert method does nothing. I have to add @Transactional to the insert or the method calling insert for it to work...

如果我像这样，即使在休眠中启用了自动提交，插入方法也不会执行任何操作。我必须将 @Transactional 添加到插入或调用插入的方法中才能使其工作...

Is there a way to make @Transactional completely optional?

有没有办法让@Transactional 完全可选？

采纳答案by Bozho

• you can't have queries without an active transaction in hibernate
• @Transactionalhas a propagationattribute, which identifies the transaction behaviour when new methods are called. The default is REQUIRED, which is what you want. Hereyou can find a graphical presentation of the concept.

• you can omit using @Transactionalif you set-up your transactional methods with aop, like this:

  <aop:config>
      <aop:pointcut id="serviceMethods"
          expression="execution(* com.company.product.service..*.*(..))" />
      <aop:advisor advice-ref="txAdvice" pointcut-ref="serviceMethods" />
  </aop:config>
  
  <tx:advice id="txAdvice" transaction-manager="transactionManager">
      <tx:attributes>
          <tx:method name="*" propagation="REQUIRED" />
      </tx:attributes>
  </tx:advice>
  

  That makes all public methods in the servicepackage transactional.

• 在休眠状态下，如果没有活动事务，您将无法进行查询
• @Transactional有一个propagation属性，用于标识调用新方法时的事务行为。默认为REQUIRED，这就是您想要的。在这里您可以找到该概念的图形演示。

• @Transactional如果使用 aop 设置事务方法，则可以省略 using ，如下所示：

  <aop:config>
      <aop:pointcut id="serviceMethods"
          expression="execution(* com.company.product.service..*.*(..))" />
      <aop:advisor advice-ref="txAdvice" pointcut-ref="serviceMethods" />
  </aop:config>
  
  <tx:advice id="txAdvice" transaction-manager="transactionManager">
      <tx:attributes>
          <tx:method name="*" propagation="REQUIRED" />
      </tx:attributes>
  </tx:advice>
  

  这使得service包中的所有公共方法都是事务性的。

Also, feel free to read the entire chapter on spring transactions.

另外，请随意阅读有关 spring 事务的整章。