|
Java EE 6 example source code file (StatelessSessionBean.java)
The Java EE 6 StatelessSessionBean.java source code/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can obtain * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt. * Sun designates this particular file as subject to the "Classpath" exception * as provided by Sun in the GPL Version 2 section of the License file that * accompanied this code. If applicable, add the following below the License * Header, with the fields enclosed by brackets [] replaced by your own * identifying information: "Portions Copyrighted [year] * [name of copyright owner]" * * Contributor(s): * * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package enterprise.locking.ejb; import enterprise.locking.entity.Part; import enterprise.locking.entity.User; import javax.ejb.Stateless; import javax.persistence.*; import java.util.Random; @Stateless public class StatelessSessionBean { @PersistenceContext private EntityManager em; private String name = "foo"; public String getName() { return name; } public void setName(String name) { this.name = name; } /** * Initializes data for given number of consumers, suppliers and parts */ public void initData(int numberOfConsumers, int numberOfSuppliers, int numberOfParts) { // user info int uid = 0; String fName = null; String lName = null; User u = null; int pid = 0; String pName = null; Part p = null; Part partRef[] = new Part[numberOfParts]; for (int i = 0; i < numberOfParts; i++) { pid++; pName = "p" + pid; p = new Part(pid, pName); p.setAmount(500); partRef[i] = p; em.persist(p); } int partIndex = 1; Random randomGenerator = new Random(); for (int i = 0; i < numberOfConsumers; i++) { uid++; fName = "f" + uid; lName = "l" + uid; u = new User(uid, fName, lName); u.setUserType(User.UserType.CONSUMER); u.setCount(2); // randam int from 0, ..., NT-1 partIndex = randomGenerator.nextInt(numberOfParts); u.setPart(partRef[partIndex]); em.persist(u); } for (int i = 0; i < numberOfSuppliers; i++) { uid++; fName = "f" + uid; lName = "l" + uid; u = new User(uid, fName, lName); u.setUserType(User.UserType.SUPPLIER); u.setCount(10); partIndex = randomGenerator.nextInt(numberOfParts); u.setPart(partRef[partIndex]); em.persist(u); } } /** * A find followed by some think time, followed by update. */ public boolean updateWithOptimisticLock(int uID, int s) { boolean updateSuccessfull = true; User u = em.find(User.class, uID); int pID = u.getPart().getId(); Part p = em.find(Part.class, pID); // Simulate think time to allow parallel threads to find Usrs in parallel. simulateThinkTimeForSecond(s); int uCount = u.getCount(); int pAmount = p.getAmount(); // update part if (u.getUserType() == User.UserType.CONSUMER) { p.setAmount(pAmount - uCount); } else { p.setAmount(pAmount + uCount); } try { em.flush(); } catch (OptimisticLockException e) { System.out.println("Got OptimisticLockException while updating with Optimistic Lock. " + "The transaction will be rolled back"); updateSuccessfull = false; } catch (PersistenceException e ) { System.out.println("Got Exception while updating with optimstic lock" + e); updateSuccessfull = false; } return updateSuccessfull; } /** * A find with pessimistic lock followed by some think time, followed by update. */ public boolean updateWithPessimisticLock(int uID, int s) { boolean updateSuccessfull = true; User u = em.find(User.class, uID); int pID = u.getPart().getId(); // Using Pessimistic lock to find the part object. Part p = em.find(Part.class, pID, LockModeType.PESSIMISTIC_WRITE); // Simulate think time to allow parallel threads to find in parallel. simulateThinkTimeForSecond(s); int uCount = u.getCount(); int pAmount = p.getAmount(); // update part if (u.getUserType() == User.UserType.CONSUMER) { p.setAmount(pAmount - uCount); } else { p.setAmount(pAmount + uCount); } try { em.flush(); } catch (PersistenceException e) { updateSuccessfull = false; } return updateSuccessfull; } public void simulateThinkTimeForSecond(int sec) { //TODO check if sleep is allowed by EE spec try { Thread.sleep(sec * 1000); } catch (Exception ex) { System.out.println("get exp in sleep"); } } } Other Java EE 6 examples (source code examples)Here is a short list of links related to this Java EE 6 StatelessSessionBean.java source code file: |
... this post is sponsored by my books ... | |
#1 New Release! |
FP Best Seller |
Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.
A percentage of advertising revenue from
pages under the /java/jwarehouse
URI on this website is
paid back to open source projects.