Package org.springframework.orm.jpa

Source Code of org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler

/*
* Copyright 2002-2007 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.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.springframework.orm.jpa;

import java.io.Serializable;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Map;
import java.util.Set;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.TransactionRequiredException;
import javax.persistence.spi.PersistenceUnitInfo;
import javax.persistence.spi.PersistenceUnitTransactionType;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.dao.DataAccessException;
import org.springframework.dao.support.PersistenceExceptionTranslator;
import org.springframework.transaction.support.TransactionSynchronizationAdapter;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CollectionUtils;

/**
* Factory for dynamic EntityManager proxies that follow the JPA spec's
* semantics for "extended" EntityManagers.
*
* <p>Supports explicit joining of a transaction through the
* <code>joinTransaction()</code> method ("application-managed extended
* EntityManager") as well as automatic joining on each operation
* ("container-managed extended EntityManager").
*
* @author Rod Johnson
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class ExtendedEntityManagerCreator {

  /**
   * Create an EntityManager that can join transactions with the
   * <code>joinTransaction()</code> method, but is not automatically
   * managed by the container.
   * @param rawEntityManager raw EntityManager
   * @param plusOperations an implementation of the EntityManagerPlusOperations
   * interface, if those operations should be exposed (may be <code>null</code>)
   * @return an application-managed EntityManager that can join transactions
   * but does not participate in them automatically
   */
  public static EntityManager createApplicationManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerPlusOperations plusOperations) {

    return createProxy(rawEntityManager, plusOperations, null, null, false);
  }

  /**
   * Create an EntityManager that can join transactions with the
   * <code>joinTransaction()</code> method, but is not automatically
   * managed by the container.
   * @param rawEntityManager raw EntityManager
   * @param plusOperations an implementation of the EntityManagerPlusOperations
   * interface, if those operations should be exposed (may be <code>null</code>)
   * @param exceptionTranslator the exception translator to use for translating
   * JPA commit/rollback exceptions during transaction synchronization
   * (may be <code>null</code>)
   * @return an application-managed EntityManager that can join transactions
   * but does not participate in them automatically
   */
  public static EntityManager createApplicationManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerPlusOperations plusOperations,
      PersistenceExceptionTranslator exceptionTranslator) {

    return createProxy(rawEntityManager, plusOperations, exceptionTranslator, null, false);
  }

  /**
   * Create an EntityManager that can join transactions with the
   * <code>joinTransaction()</code> method, but is not automatically
   * managed by the container.
   * @param rawEntityManager raw EntityManager
   * @param emfInfo the EntityManagerFactoryInfo to obtain the
   * EntityManagerPlusOperations and PersistenceUnitInfo from
   * @return an application-managed EntityManager that can join transactions
   * but does not participate in them automatically
   */
  public static EntityManager createApplicationManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerFactoryInfo emfInfo) {

    return createProxy(rawEntityManager, emfInfo, false);
  }


  /**
   * Create an EntityManager that automatically joins transactions on each
   * operation in a transaction.
   * @param rawEntityManager raw EntityManager
   * @param plusOperations an implementation of the EntityManagerPlusOperations
   * interface, if those operations should be exposed (may be <code>null</code>)
   * @return a container-managed EntityManager that will automatically participate
   * in any managed transaction
   */
  public static EntityManager createContainerManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerPlusOperations plusOperations) {

    return createProxy(rawEntityManager, plusOperations, null, null, true);
  }

  /**
   * Create an EntityManager that automatically joins transactions on each
   * operation in a transaction.
   * @param rawEntityManager raw EntityManager
   * @param plusOperations an implementation of the EntityManagerPlusOperations
   * interface, if those operations should be exposed (may be <code>null</code>)
   * @param exceptionTranslator the exception translator to use for translating
   * JPA commit/rollback exceptions during transaction synchronization
   * (may be <code>null</code>)
   * @return a container-managed EntityManager that will automatically participate
   * in any managed transaction
   */
  public static EntityManager createContainerManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerPlusOperations plusOperations,
      PersistenceExceptionTranslator exceptionTranslator) {

    return createProxy(rawEntityManager, plusOperations, exceptionTranslator, null, true);
  }

  /**
   * Create an EntityManager that automatically joins transactions on each
   * operation in a transaction.
   * @param rawEntityManager raw EntityManager
   * @param emfInfo the EntityManagerFactoryInfo to obtain the
   * EntityManagerPlusOperations and PersistenceUnitInfo from
   * @return a container-managed EntityManager that will automatically participate
   * in any managed transaction
   */
  public static EntityManager createContainerManagedEntityManager(
      EntityManager rawEntityManager, EntityManagerFactoryInfo emfInfo) {

    return createProxy(rawEntityManager, emfInfo, true);
  }


  /**
   * Create an EntityManager that automatically joins transactions on each
   * operation in a transaction.
   * @param emf the EntityManagerFactory to create the EntityManager with.
   * If this implements the EntityManagerFactoryInfo interface, appropriate handling
   * of the native EntityManagerFactory and available EntityManagerPlusOperations
   * will automatically apply.
   * @return a container-managed EntityManager that will automatically participate
   * in any managed transaction
   * @see javax.persistence.EntityManagerFactory#createEntityManager()
   */
  public static EntityManager createContainerManagedEntityManager(EntityManagerFactory emf) {
    return createContainerManagedEntityManager(emf, null);
  }

  /**
   * Create an EntityManager that automatically joins transactions on each
   * operation in a transaction.
   * @param emf the EntityManagerFactory to create the EntityManager with.
   * If this implements the EntityManagerFactoryInfo interface, appropriate handling
   * of the native EntityManagerFactory and available EntityManagerPlusOperations
   * will automatically apply.
   * @param properties the properties to be passed into the <code>createEntityManager</code>
   * call (may be <code>null</code>)
   * @return a container-managed EntityManager that will automatically participate
   * in any managed transaction
   * @see javax.persistence.EntityManagerFactory#createEntityManager(java.util.Map)
   */
  public static EntityManager createContainerManagedEntityManager(EntityManagerFactory emf, Map properties) {
    Assert.notNull(emf, "EntityManagerFactory must not be null");
    if (emf instanceof EntityManagerFactoryInfo) {
      EntityManagerFactoryInfo emfInfo = (EntityManagerFactoryInfo) emf;
      EntityManagerFactory nativeEmf = emfInfo.getNativeEntityManagerFactory();
      EntityManager rawEntityManager = (!CollectionUtils.isEmpty(properties) ?
          nativeEmf.createEntityManager(properties) : nativeEmf.createEntityManager());
      return createProxy(rawEntityManager, emfInfo, true);
    }
    else {
      EntityManager rawEntityManager = (!CollectionUtils.isEmpty(properties) ?
          emf.createEntityManager(properties) : emf.createEntityManager());
      return createProxy(rawEntityManager, null, null, null, true);
    }
  }


  /**
   * Actually create the EntityManager proxy.
   * @param rawEntityManager raw EntityManager
   * @param emfInfo the EntityManagerFactoryInfo to obtain the
   * EntityManagerPlusOperations and PersistenceUnitInfo from
   * @param containerManaged whether to follow container-managed EntityManager
   * or application-managed EntityManager semantics
   * @return the EntityManager proxy
   */
  private static EntityManager createProxy(
      EntityManager rawEntityManager, EntityManagerFactoryInfo emfInfo, boolean containerManaged) {

    Assert.notNull(emfInfo, "EntityManagerFactoryInfo must not be null");
    JpaDialect jpaDialect = emfInfo.getJpaDialect();
    EntityManagerPlusOperations plusOperations = null;
    if (jpaDialect != null && jpaDialect.supportsEntityManagerPlusOperations()) {
      plusOperations = jpaDialect.getEntityManagerPlusOperations(rawEntityManager);
    }
    PersistenceUnitInfo pui = emfInfo.getPersistenceUnitInfo();
    Boolean jta = (pui != null ? pui.getTransactionType() == PersistenceUnitTransactionType.JTA : null);
    return createProxy(rawEntityManager, plusOperations, jpaDialect, jta, containerManaged);
  }

  /**
   * Actually create the EntityManager proxy.
   * @param rawEntityManager raw EntityManager
   * @param plusOperations an implementation of the EntityManagerPlusOperations
   * interface, if those operations should be exposed (may be <code>null</code>)
   * @param exceptionTranslator the PersistenceException translator to use
   * @param jta whether to create a JTA-aware EntityManager
   * (or <code>null</code> if not known in advance)
   * @param containerManaged whether to follow container-managed EntityManager
   * or application-managed EntityManager semantics
   * @return the EntityManager proxy
   */
  private static EntityManager createProxy(
      EntityManager rawEntityManager, EntityManagerPlusOperations plusOperations,
      PersistenceExceptionTranslator exceptionTranslator, Boolean jta, boolean containerManaged) {

    Assert.notNull(rawEntityManager, "EntityManager must not be null");
    Set ifcs = ClassUtils.getAllInterfacesAsSet(rawEntityManager);
    ifcs.add(EntityManagerProxy.class);
    if (plusOperations != null) {
      ifcs.add(EntityManagerPlusOperations.class);
    }
    return (EntityManager) Proxy.newProxyInstance(
        ExtendedEntityManagerCreator.class.getClassLoader(),
        (Class[]) ifcs.toArray(new Class[ifcs.size()]),
        new ExtendedEntityManagerInvocationHandler(
            rawEntityManager, plusOperations, exceptionTranslator, jta, containerManaged));
  }


  /**
   * InvocationHandler for extended EntityManagers as defined in the JPA spec.
   */
  private static class ExtendedEntityManagerInvocationHandler implements InvocationHandler, Serializable {

    private static final Log logger = LogFactory.getLog(ExtendedEntityManagerInvocationHandler.class);

    private final EntityManager target;

    private final EntityManagerPlusOperations plusOperations;

    private final PersistenceExceptionTranslator exceptionTranslator;

    private final boolean containerManaged;

    private boolean jta;

    private ExtendedEntityManagerInvocationHandler(
        EntityManager target, EntityManagerPlusOperations plusOperations,
        PersistenceExceptionTranslator exceptionTranslator, Boolean jta, boolean containerManaged) {

      this.target = target;
      this.plusOperations = plusOperations;
      this.exceptionTranslator = exceptionTranslator;
      this.jta = (jta != null ? jta.booleanValue() : isJtaEntityManager());
      this.containerManaged = containerManaged;
    }

    private boolean isJtaEntityManager() {
      try {
        this.target.getTransaction();
        return false;
      }
      catch (IllegalStateException ex) {
        logger.debug("Cannot access EntityTransaction handle - assuming we're in a JTA environment");
        return true;
      }
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
      // Invocation on EntityManager interface coming in...

      if (method.getName().equals("equals")) {
        // Only consider equal when proxies are identical.
        return (proxy == args[0]);
      }
      else if (method.getName().equals("hashCode")) {
        // Use hashCode of EntityManager proxy.
        return hashCode();
      }
      else if (method.getName().equals("getTargetEntityManager")) {
        return this.target;
      }
      else if (method.getName().equals("isOpen")) {
        if (this.containerManaged) {
          return true;
        }
      }
      else if (method.getName().equals("close")) {
        if (this.containerManaged) {
          throw new IllegalStateException("Invalid usage: Cannot close a container-managed EntityManager");
        }
      }
      else if (method.getName().equals("getTransaction")) {
        if (this.containerManaged) {
          throw new IllegalStateException(
              "Cannot execute getTransaction() on a container-managed EntityManager");
        }
      }
      else if (method.getName().equals("joinTransaction")) {
        doJoinTransaction(true);
        return null;
      }

      // Do automatic joining if required.
      if (this.containerManaged && method.getDeclaringClass().isInterface()) {
        doJoinTransaction(false);
      }

      // Invoke method on current EntityManager.
      try {
        if (method.getDeclaringClass().equals(EntityManagerPlusOperations.class)) {
          return method.invoke(this.plusOperations, args);
        }
        else {
          return method.invoke(this.target, args);
        }
      }
      catch (InvocationTargetException ex) {
        throw ex.getTargetException();
      }
    }

    /**
     * Join an existing transaction, if not already joined.
     * @param enforce whether to enforce the transaction
     * (i.e. whether failure to join is considered fatal)
     */
    private void doJoinTransaction(boolean enforce) {
      if (this.jta) {
        // Let's try whether we're in a JTA transaction.
        try {
          this.target.joinTransaction();
          logger.debug("Joined JTA transaction");
        }
        catch (TransactionRequiredException ex) {
          if (!enforce) {
            logger.debug("No JTA transaction to join: " + ex);
          }
          else {
            throw ex;
          }
        }
      }
      else {
        if (TransactionSynchronizationManager.isSynchronizationActive()) {
          if (!TransactionSynchronizationManager.hasResource(this.target) &&
              !this.target.getTransaction().isActive()) {
            enlistInCurrentTransaction();
          }
          logger.debug("Joined local transaction");
        }
        else {
          if (!enforce) {
            logger.debug("No local transaction to join");
          }
          else {
            throw new TransactionRequiredException("No local transaction to join");
          }
        }
      }
    }

    /**
     * Enlist this application-managed EntityManager in the current transaction.
     */
    private void enlistInCurrentTransaction() {
      // Resource local transaction, need to acquire the EntityTransaction,
      // start a transaction now and enlist a synchronization for
      // commit or rollback later.
      EntityTransaction et = this.target.getTransaction();
      et.begin();
      if (logger.isDebugEnabled()) {
        logger.debug("Starting resource local transaction on application-managed " +
            "EntityManager [" + this.target + "]");
      }
      EntityManagerHolder emh = new EntityManagerHolder(this.target);
      ExtendedEntityManagerSynchronization extendedEntityManagerSynchronization =
          new ExtendedEntityManagerSynchronization(emh, this.exceptionTranslator);
      TransactionSynchronizationManager.bindResource(this.target,
          extendedEntityManagerSynchronization);
      TransactionSynchronizationManager.registerSynchronization(extendedEntityManagerSynchronization);
    }
  }


  /**
   * TransactionSynchronization enlisting an extended EntityManager
   * with a current Spring transaction.
   */
  private static class ExtendedEntityManagerSynchronization extends TransactionSynchronizationAdapter {

    private final EntityManagerHolder entityManagerHolder;

    private final PersistenceExceptionTranslator exceptionTranslator;

    private boolean holderActive = true;

    public ExtendedEntityManagerSynchronization(
        EntityManagerHolder emHolder, PersistenceExceptionTranslator exceptionTranslator) {

      this.entityManagerHolder = emHolder;
      this.exceptionTranslator = exceptionTranslator;
    }

    public int getOrder() {
      return EntityManagerFactoryUtils.ENTITY_MANAGER_SYNCHRONIZATION_ORDER + 1;
    }

    public void suspend() {
      if (this.holderActive) {
        TransactionSynchronizationManager.unbindResource(this.entityManagerHolder.getEntityManager());
      }
    }

    public void resume() {
      if (this.holderActive) {
        TransactionSynchronizationManager.bindResource(
            this.entityManagerHolder.getEntityManager(), this.entityManagerHolder);
      }
    }

    public void beforeCompletion() {
      TransactionSynchronizationManager.unbindResource(this.entityManagerHolder.getEntityManager());
      this.holderActive = false;
    }

    public void afterCommit() {
      // Trigger commit here to let exceptions propagate to the caller.
      try {
        this.entityManagerHolder.getEntityManager().getTransaction().commit();
      }
      catch (RuntimeException ex) {
        throw convertCompletionException(ex);
      }
    }

    public void afterCompletion(int status) {
      this.entityManagerHolder.setSynchronizedWithTransaction(false);
      if (status != STATUS_COMMITTED) {
        // Haven't had an afterCommit call: trigger a rollback.
        try {
          this.entityManagerHolder.getEntityManager().getTransaction().rollback();
        }
        catch (RuntimeException ex) {
          throw convertCompletionException(ex);
        }
      }
      // Don't close the EntityManager... That's up to the user.
    }

    private RuntimeException convertCompletionException(RuntimeException ex) {
      DataAccessException daex = (this.exceptionTranslator != null) ?
          this.exceptionTranslator.translateExceptionIfPossible(ex) :
          EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(ex);
      return (daex != null ? daex : ex);
    }
  }

}
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