每次会话的JPA 2（Hibernate）持久化上下文 - 关闭连接

我正在尝试使用JBoss 4.3.0和Hibernate 4.3.5在有状态的专有Web框架上实现实体管理器每会话模式 . 简而言之，目标是：

• 第一个HTTP请求从数据库加载具有延迟加载属性的实体A.

• 在第二个请求中，实体A的延迟加载属性可以在没有例如的情况下访问 . 创建一个新的EntityManager并调用例如entityManager.merge（entityA） .

Entitymanager-per-conversation似乎是完美的选择 . 这是我的尝试：

public class EntityManagerHolder {
    private static ThreadLocal<EntityManager> entityManager = new ThreadLocal<EntityManager>();        
    private static EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("myPersistence");
    private static ConnectionProvider connectionProvider = new MyConnectionProvider();

    public static synchronized EntityManager getEntityManager() {
        createEntityManagerIfNeeded();
        return entityManager.get();
    }

    public static synchronized void createEntityManagerIfNeeded() {
        if (entityManager.get() == null) {
            // Start the conversation
            EntityManager newEntityManager = entityManagerFactory.createEntityManager();
            entityManager.set(newEntityManager);
            newEntityManager.getTransaction().begin();
        } else {
            // Entitymanager is alive but may have lost its connection
            EntityManager existingEntityManager = entityManager.get();
            SessionImpl session = existingEntityManager.unwrap(SessionImpl.class);

            try {
                if (session.connection() == null || session.connection().isClosed()) {
                    session.reconnect(connectionProvider.getConnection());
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

persistence.xml中：

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
  <persistence-unit name="myEntityManagerFactory">
    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
    <properties>
      <!-- Scan for annotated classes and Hibernate mapping XML files from this JAR -->
      <property name="hibernate.archive.autodetection" value="class, hbm" />
      <!-- Database connection settings: Use framework connections for database connectivity -->
      <property name="hibernate.connection.provider_class" value="foo.bar.MyConnectionProvider"/>
    </properties>
  </persistence-unit>
</persistence>

当新的HTTP请求通过框架到达时，我调用EntityManagerHolder.createEntityManagerIfNeeded（） . 在第二个HTTP请求中，EntityManager的JDBC连接已关闭，尝试通过session.reconnect（）恢复它会导致异常：

java.lang.IllegalStateException: cannot manually reconnect unless Connection was originally supplied

org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.manualReconnect(LogicalConnectionImpl.java:296)
org.hibernate.internal.SessionImpl.reconnect(SessionImpl.java:478)

我意识到我已经找到了这种模式的基于过滤器的Hibernate-specific sample implementation，但还没有设法将它弯曲到我的需要 .