你能在java中每个线程只有一个hibernate会话吗？ [英] Can you only have one hibernate session per thread in java?

问题描述

所以我正在开发一个没有多线程的应用程序。我们有一个主要的业务逻辑方法，可以像这样打开一个Hibernate会话：
$ b

  session = HibernateSessionFactory.getSession（）; 
 tx = session.beginTransaction（）; 
  

然后执行一些轻量级数据库操作（少数选择）。然后调用一个我在子类中重写的方法来执行另一个选择。我无法将会话作为参数传递，而无需更新20ish子类。

我尝试打开新会话和事务并在完成后关闭它们，但是当我的方法被踢回了商业方法，我得到了一个关于会话关闭的错误。我试图不关闭会议并提交交易，但那也不起作用。

现在我只是使用它，一切似乎都在本地正常工作：

  session = HibernateSessionFactory.getSession（）; 
 tx = session.getTransaction（）; 
  

我只关闭会话并回滚错误。我只是不确定getSession是否会始终返回已经打开的会话。我是否有权假定每个线程每次只能打开一个会话？

以下是getSession的实现：

 会话会话=（会话）threadLocal.get（）; 
 
 if（session == null ||！session.isOpen（））
 {
 if（sessionFactory == null）
 {
 rebuildSessionFactory ）; 
} 
 session =（sessionFactory！= null）？ sessionFactory.openSession（）：null; 
 threadLocal.set（session）; 
} 
 
返回会话; 
  

谢谢！

解决方案

从我的理解，getSession将返回一个新的休眠会话。在Hibernate中有两种使用会话的方法，这些方法在文档中描述了事务模式： https://docs.jboss.org/hibernate/orm/4.2/devguide/en-US/html/ch02.html

到数据库的实际会话取决于您与数据库的连接。大多数人使用连接池，如C3P0，可用于确保会话重用和加速代码。

我使用的最佳结构是在应用程序启动时创建一个SessionFactory，因为这会将连接池设置为数据库。然后，利用可能的单例模式来保存一个SessionFactory，为您从单个SessionFactory执行的每个事务请求新的会话。 Hibernate将利用底层连接池来处理会话重用，以加快速度和优化。

So I'm working on an application without multi threading. We have a main business logic method that opens a Hibernate session like this:

session = HibernateSessionFactory.getSession();
tx = session.beginTransaction();

and then performs some light DB operations (a few selects). A method that I've overridden in a subclass is then called that needs to perform another select. I can't pass the session as a parameter without having to update 20ish subclasses.

I tried opening a new session and transaction and closing them when I was done, but when my method kicked back to the business method, I got an error that the session was closed. I tried not closing the session and committing the transaction, but that wasn't working either.

Right now I'm just using this and everything seems to be working properly locally:

session = HibernateSessionFactory.getSession();
tx = session.getTransaction();

and I'm only closing the session and rolling back incase of errors. I'm just uncertain if getSession will always return the session thats already open. Am I right to assume that only one session can be open at a time per thread?

Here's the implementation of getSession:

Session session = (Session) threadLocal.get();

    if (session == null || !session.isOpen())
    {
        if (sessionFactory == null)
        {
            rebuildSessionFactory();
        }
        session = (sessionFactory != null) ? sessionFactory.openSession() : null;
        threadLocal.set(session);
    }

    return session;

Thanks!

解决方案

From my understanding, getSession will return a new hibernate session. There are two methods of using sessions in Hibernate that is described transactional patterns in the document: https://docs.jboss.org/hibernate/orm/4.2/devguide/en-US/html/ch02.html

The actual "session" to the database depends on your connection to the database. Most people utilize a connection pool, like C3P0 that can be used to ensure session reuse and speed up your code.

The best structure I use is to create a SessionFactory once in application launch, as this sets up the connection pool to the database. Then, utilizing maybe a singleton pattern to keep a single SessionFactory, request new sessions for each transaction you perform from the single SessionFactory. Hibernate will utilize the underlying connection pool to handle session reuse for speed and optimization.

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