LocalSessionFactoryBean and HibernateTransactionManager for JPA setup

SessionHolder extends EntityManagerHolder now, allowing for @PersistenceContext and co to interact with HibernateTransactionManager's thread-bound transactions, and SpringSessionContext is capable of interacting with JpaTransactionManager by detecting a plain EntityManagerHolder as well.

Issue: SPR-17002

spring-orm/src/main/java/org/springframework/orm/hibernate5/HibernateTemplate.java

@@ -45,6 +45,7 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.lang.Nullable;
+import org.springframework.transaction.support.ResourceHolderSupport;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
@@ -1117,8 +1118,8 @@ public class HibernateTemplate implements HibernateOperations, InitializingBean
 			criteria.setMaxResults(getMaxResults());
 		}
 
-		SessionHolder sessionHolder =
-				(SessionHolder) TransactionSynchronizationManager.getResource(obtainSessionFactory());
+		ResourceHolderSupport sessionHolder =
+				(ResourceHolderSupport) TransactionSynchronizationManager.getResource(obtainSessionFactory());
 		if (sessionHolder != null && sessionHolder.hasTimeout()) {
 			criteria.setTimeout(sessionHolder.getTimeToLiveInSeconds());
 		}
@@ -1146,8 +1147,8 @@ public class HibernateTemplate implements HibernateOperations, InitializingBean
 			queryObject.setMaxResults(getMaxResults());
 		}
 
-		SessionHolder sessionHolder =
-				(SessionHolder) TransactionSynchronizationManager.getResource(obtainSessionFactory());
+		ResourceHolderSupport sessionHolder =
+				(ResourceHolderSupport) TransactionSynchronizationManager.getResource(obtainSessionFactory());
 		if (sessionHolder != null && sessionHolder.hasTimeout()) {
 			queryObject.setTimeout(sessionHolder.getTimeToLiveInSeconds());
 		}

spring-orm/src/main/java/org/springframework/orm/hibernate5/SessionHolder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,18 +16,20 @@
 
 package org.springframework.orm.hibernate5;
 
+import javax.persistence.EntityManager;
+
 import org.hibernate.FlushMode;
 import org.hibernate.Session;
 import org.hibernate.Transaction;
 
 import org.springframework.lang.Nullable;
-import org.springframework.transaction.support.ResourceHolderSupport;
-import org.springframework.util.Assert;
+import org.springframework.orm.jpa.EntityManagerHolder;
 
 /**
- * Session holder, wrapping a Hibernate Session and a Hibernate Transaction.
- * HibernateTransactionManager binds instances of this class to the thread,
- * for a given SessionFactory.
+ * Resource holder wrapping a Hibernate {@link Session} (plus an optional {@link Transaction}).
+ * {@link HibernateTransactionManager} binds instances of this class to the thread,
+ * for a given {@link org.hibernate.SessionFactory}. Extends {@link EntityManagerHolder}
+ * as of 5.1, automatically exposing an {@code EntityManager} handle on Hibernate 5.2+.
  *
  * <p>Note: This is an SPI class, not intended to be used by applications.
  *
@@ -36,7 +38,7 @@ import org.springframework.util.Assert;
  * @see HibernateTransactionManager
  * @see SessionFactoryUtils
  */
-public class SessionHolder extends ResourceHolderSupport {
+public class SessionHolder extends EntityManagerHolder {
 
 	private final Session session;
 
@@ -48,7 +50,7 @@ public class SessionHolder extends ResourceHolderSupport {
 
 
 	public SessionHolder(Session session) {
-		Assert.notNull(session, "Session must not be null");
+		super(EntityManager.class.isInstance(session) ? session : null);
 		this.session = session;
 	}
 
@@ -59,6 +61,7 @@ public class SessionHolder extends ResourceHolderSupport {
 
 	public void setTransaction(@Nullable Transaction transaction) {
 		this.transaction = transaction;
+		setTransactionActive(transaction != null);
 	}
 
 	@Nullable

spring-orm/src/main/java/org/springframework/orm/hibernate5/SpringSessionContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,12 +29,13 @@ import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.engine.transaction.jta.platform.spi.JtaPlatform;
 
 import org.springframework.lang.Nullable;
+import org.springframework.orm.jpa.EntityManagerHolder;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 
 /**
- * Implementation of Hibernate 3.1's CurrentSessionContext interface
- * that delegates to Spring's SessionFactoryUtils for providing a
- * Spring-managed current Session.
+ * Implementation of Hibernate 3.1's {@link CurrentSessionContext} interface
+ * that delegates to Spring's {@link SessionFactoryUtils} for providing a
+ * Spring-managed current {@link Session}.
  *
  * <p>This CurrentSessionContext implementation can also be specified in custom
  * SessionFactory setup through the "hibernate.current_session_context_class"
@@ -86,6 +87,7 @@ public class SpringSessionContext implements CurrentSessionContext {
 			return (Session) value;
 		}
 		else if (value instanceof SessionHolder) {
+			// HibernateTransactionManager
 			SessionHolder sessionHolder = (SessionHolder) value;
 			Session session = sessionHolder.getSession();
 			if (!sessionHolder.isSynchronizedWithTransaction() &&
@@ -104,13 +106,18 @@ public class SpringSessionContext implements CurrentSessionContext {
 			}
 			return session;
 		}
+		else if (value instanceof EntityManagerHolder) {
+			// JpaTransactionManager
+			return ((EntityManagerHolder) value).getEntityManager().unwrap(Session.class);
+		}
 
 		if (this.transactionManager != null && this.jtaSessionContext != null) {
 			try {
 				if (this.transactionManager.getStatus() == Status.STATUS_ACTIVE) {
 					Session session = this.jtaSessionContext.currentSession();
 					if (TransactionSynchronizationManager.isSynchronizationActive()) {
-						TransactionSynchronizationManager.registerSynchronization(new SpringFlushSynchronization(session));
+						TransactionSynchronizationManager.registerSynchronization(
+								new SpringFlushSynchronization(session));
 					}
 					return session;
 				}

spring-orm/src/main/java/org/springframework/orm/jpa/EntityManagerHolder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,9 +24,12 @@ import org.springframework.transaction.support.ResourceHolderSupport;
 import org.springframework.util.Assert;
 
 /**
- * Holder wrapping a JPA EntityManager.
- * JpaTransactionManager binds instances of this class to the thread,
- * for a given EntityManagerFactory.
+ * Resource holder wrapping a JPA {@link EntityManager}.
+ * {@link JpaTransactionManager} binds instances of this class to the thread,
+ * for a given {@link javax.persistence.EntityManagerFactory}.
+ *
+ * <p>Also serves as a base class for {@link org.springframework.orm.hibernate5.SessionHolder},
+ * as of 5.1.
  *
  * <p>Note: This is an SPI class, not intended to be used by applications.
  *
@@ -37,6 +40,7 @@ import org.springframework.util.Assert;
  */
 public class EntityManagerHolder extends ResourceHolderSupport {
 
+	@Nullable
 	private final EntityManager entityManager;
 
 	private boolean transactionActive;
@@ -45,13 +49,13 @@ public class EntityManagerHolder extends ResourceHolderSupport {
 	private SavepointManager savepointManager;
 
 
-	public EntityManagerHolder(EntityManager entityManager) {
-		Assert.notNull(entityManager, "EntityManager must not be null");
+	public EntityManagerHolder(@Nullable EntityManager entityManager) {
 		this.entityManager = entityManager;
 	}
 
 
 	public EntityManager getEntityManager() {
+		Assert.state(this.entityManager != null, "No EntityManager available");
 		return this.entityManager;
 	}