OpenSessionBackgroundProcess

package com.afs.web.common.struts.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import org.apache.struts2.interceptor.BackgroundProcess;
import org.springframework.orm.jpa.EntityManagerFactoryUtils;
import org.springframework.orm.jpa.EntityManagerHolder;
import org.springframework.transaction.support.TransactionSynchronizationManager;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

/**
 * Used in conjunction with {@link OpenSessionExecuteAndWaitInterceptor}
 */
public class OpenSessionBackgroundProcess extends BackgroundProcess {

    EntityManagerFactory entityManagerFactory;
    protected boolean initializationComplete;
    private Object lock = new Object(); // used for synchronization

    public OpenSessionBackgroundProcess(String name, ActionInvocation invocation, int threadPriority, EntityManagerFactory entityManagerFactory) {
        super(name, invocation, threadPriority);
        this.entityManagerFactory = entityManagerFactory;
        initializationComplete = true;
        synchronized (lock) {
            lock.notify();
        }
    }

    protected void beforeInvocation() throws Exception {
        while (!initializationComplete) {
            try {
                synchronized (lock) {
                    lock.wait(100);
                }
            } catch (InterruptedException e) {
                // behavior ignores cause of re-awakening.
            }
        }
        EntityManager em = entityManagerFactory.createEntityManager();
        TransactionSynchronizationManager.bindResource(entityManagerFactory, new EntityManagerHolder(em));
        super.beforeInvocation();
    }

    protected void afterInvocation() throws Exception {
        super.afterInvocation();
        EntityManagerHolder emHolder = (EntityManagerHolder)
        TransactionSynchronizationManager.unbindResource(entityManagerFactory);
        EntityManagerFactoryUtils.closeEntityManager(emHolder.getEntityManager());
    }
}