在eclipselink中设置隔离级别

Question

我想使用eclipse链接设置隔离级别,
我尝试了这两种方法:

1. java.sql.Connection中

   mgr = EMF.get().createEntityManager();
   tx = mgr.getTransaction();
   tx.begin();
   
   java.sql.Connection connection = mgr.unwrap(java.sql.Connection.class);
   connection.setTransactionIsolation(java.sql.Connection.TRANSACTION_READ_COMMITTED);
   System.out.println("Connection: "+connection.getTransactionIsolation());
   //prints TRANSACTION_READ_COMMITED as expected
   
   org.eclipse.persistence.sessions.DatabaseLogin databaseLogin = new DatabaseLogin();
   System.out.println("DatabaseLoging: "+databaseLogin.getTransactionIsolation());
   //prints -1, representing transaction isolation is not set
   

2. DatabaseLogin setTransationIsolation方法

   mgr = EMF.get().createEntityManager();
   tx = mgr.getTransaction();
   tx.begin();
   
   org.eclipse.persistence.sessions.DatabaseLogin databaseLogin = new DatabaseLogin();
   databaseLogin.setTransactionIsolation(DatabaseLogin.TRANSACTION_READ_COMMITTED);
   System.out.println("DatabaseLoging: "+databaseLogin.getTransactionIsolation());
   //prints TRANSACTION_READ_COMMITED as expected
   
   java.sql.Connection connection = mgr.unwrap(java.sql.Connection.class);
   System.out.println("Connection: "+connection.getTransactionIsolation());
   //prints TRANSACTION_REPEATABLE_READ
   

如您所见,getTransacationIsolation()方法的返回值之间存在一些不一致.我的问题是,在两种情况下都确实设置了哪种事务隔离？我知道默认情况下eclipse链接使用不同的连接进行读写操作,DatabaseLogin.setTransactionIsolation应该为两个连接设置隔离级别,那么为什么Connection.getTransactionIsolation仍然返回另一个隔离级别？

我正在使用应用程序范围的EntityManager,JPA 2.0,EclipseLink 2.5.2.
如果有更好的方法设置事务隔离,请告诉我.

Answer 1

在使用eclipse链接暂停一小段时间后,我终于找到了如何设置事务隔离级别.
正如@Chris在他的回答中正确提到的,我需要获得DatabaseLogin会话使用.在对eclipse链接会话进行了一些小的研究后,我发现,我可以Session自己更改属性SessionCustomizer,请参阅下面的代码:

package com.filip.blabla;
import org.eclipse.persistence.sessions.DatabaseLogin;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.sessions.factories.SessionCustomizer;

public class DFSessionCustomizer implements SessionCustomizer {
        @Override
        public void customize(Session session) throws Exception {
            DatabaseLogin databaseLogin = (DatabaseLogin) session.getDatasourceLogin();
            databaseLogin.setTransactionIsolation(DatabaseLogin.TRANSACTION_READ_COMMITTED);
        }

}

在persistence.xml中设置SessionCustomizer

<property name="eclipselink.session.customizer" value="com.filip.blabla.DFSessionCustomizer"/>