Welcome!

Java IoT Authors: Liz McMillan, Elizabeth White, Pat Romanski, Yeshim Deniz, Paul Simmons

Related Topics: @CloudExpo, Java IoT, Machine Learning , Apache

@CloudExpo: Blog Feed Post

Translating the NetBeans Generated JPA Controller | @CloudExpo [#Cloud]

The NetBeans New File wizards greatly simplify writing boilerplate code

The NetBeans New File wizards greatly simplify writing boilerplate code. One specific instance is the creation of JPA Controller Classes from an Entity Classes. The class file, or files, written for you will contain all the basic methods of JPA for CRUD operations on the entity or entities that you have. The only small issue is that this class is written for a standalone environment such as what you would find in an environment that does not support Context Dependency Injection. To use this class in a GlassFish environment or other container we have to make some minor changes.

When working with GlassFish the first step is to create the glassfish-resources.xml and then the persistence.xml file. If the database and its tables have not been created yet then this is the time to do this. Now create the Entity Classes from Database, also shown in the New File dialog below.

With all this in place you simply have to create a New File for the project in the category Persistence and the File Type of JPA Controller Classes from Entity Classes.

Image01

The next dialog will ask you which entities you wish to have a controller class written for. It should show you the entities you have created for your project. They will appear in the Available Entity Classes box and you use the buttons to move the ones that you want. In my example there is just one entity and I have added it to the Selected Entities Classes box.

Image02

In the next step you must select the package name for the classes that will be created for you. You can use a package that already exists.

Image03

When you Finish you will see the package you created with a file that has the name of the Entity class followed by JpaController.java. In my example it is FishJpaController.java. You will also find an additional package that ends in exceptions that contains custom Exception classes that provide more informative exception types.

Image04

When you open the file you will see the class that has been written for you.

package com.kenfogel.beans;

import com.kenfogel.beans.exceptions.NonexistentEntityException;
import com.kenfogel.beans.exceptions.RollbackFailureException;
import com.kenfogel.entities.Fish;
import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Query;
import javax.persistence.EntityNotFoundException;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import javax.transaction.UserTransaction;

/**
*
* @author Ken
*/
public class FishJpaController implements Serializable {

public FishJpaController(UserTransaction utx, EntityManagerFactory emf) {
this.utx = utx;
this.emf = emf;
}
private UserTransaction utx = null;
private EntityManagerFactory emf = null;

public EntityManager getEntityManager() {
return emf.createEntityManager();
}

public void create(Fish fish) throws RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
em.persist(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}

public void edit(Fish fish) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
fish = em.merge(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
String msg = ex.getLocalizedMessage();
if (msg == null || msg.length() == 0) {
Integer id = fish.getId();
if (findFish(id) == null) {
throw new NonexistentEntityException("The fish with id " + id + " no longer exists.");
}
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}

public void destroy(Integer id) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
Fish fish;
try {
fish = em.getReference(Fish.class, id);
fish.getId();
} catch (EntityNotFoundException enfe) {
throw new NonexistentEntityException("The fish with id " + id + " no longer exists.", enfe);
}
em.remove(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}

public List<Fish> findFishEntities() {
return findFishEntities(true, -1, -1);
}

public List<Fish> findFishEntities(int maxResults, int firstResult) {
return findFishEntities(false, maxResults, firstResult);
}

private List<Fish> findFishEntities(boolean all, int maxResults, int firstResult) {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Fish.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
} finally {
em.close();
}
}

public Fish findFish(Integer id) {
EntityManager em = getEntityManager();
try {
return em.find(Fish.class, id);
} finally {
em.close();
}
}

public int getFishCount() {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
Root<Fish> rt = cq.from(Fish.class);
cq.select(em.getCriteriaBuilder().count(rt));
Query q = em.createQuery(cq);
return ((Long) q.getSingleResult()).intValue();
} finally {
em.close();
}
}

}

The changes that you have to make are quite straightforward. First, we need to make this class a managed bean and change the EntityManager and UserTransaction into Injected references.

@Named
@SessionScoped
public class FishJpaControllerUpdate implements Serializable {

@Resource
private UserTransaction utx;

@PersistenceContext
private EntityManager en;

NetBeans will help you in adding the necessary imports. The next step is to delete the constructor. As a managed bean you must have a default constructor. If you dislike not seeing a constructor in your class then you can add an empty one.

/**
* Default constructor
*/
public FishJpaControllerUpdate() {
}

Delete the method getEntityManager(). CDI will take care of creating the EntityManager for you.

The last step is to modify every method in the class that has as a first line:

EntityManager em = null;

We don’t need to call upon getEntityManager nor do we need to close the EntityManager when we are finished.

The create method:

public void create(Fish fish) throws RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
em.persist(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}

Becomes:

public void create(Fish fish) throws RollbackFailureException, Exception {
try {
utx.begin();
em.persist(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
}
}

The query method findFishEntities:

private List<Fish> findFishEntities(boolean all, int maxResults, int firstResult) {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Fish.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
} finally {
em.close();
}
}

Becomes:

private List<Fish> findFishEntities(boolean all, int maxResults, int firstResult) {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Fish.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
}

Clean up the rest of the methods and your controller will look like, with my added comments, the following:

package com.kenfogel.beans;

import com.kenfogel.beans.exceptions.NonexistentEntityException;
import com.kenfogel.beans.exceptions.RollbackFailureException;
import com.kenfogel.entities.Fish;
import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.persistence.EntityNotFoundException;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import javax.transaction.UserTransaction;
import javax.annotation.Resource;
import javax.inject.Named;
import javax.enterprise.context.SessionScoped;
import javax.persistence.PersistenceContext;
import javax.transaction.HeuristicMixedException;
import javax.transaction.HeuristicRollbackException;
import javax.transaction.NotSupportedException;
import javax.transaction.RollbackException;
import javax.transaction.SystemException;

/**
*
* @author kfogel
*/
@Named
@SessionScoped
public class FishJpaControllerUpdate implements Serializable {

@Resource
private UserTransaction utx;

@PersistenceContext
private EntityManager em;

/**
* Default constructor
*/
public FishJpaControllerUpdate() {
}

/**
* Take a new or detached entity and add it as a new record in the table
*
* @param fish
* @throws RollbackFailureException
* @throws Exception
*/
public void create(Fish fish) throws RollbackFailureException, Exception {
try {
utx.begin();
em.persist(fish);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
}
}

/**
* Take a detached entity and update the matching record in the table
*
* @param fish
* @throws NonexistentEntityException
* @throws RollbackFailureException
* @throws Exception
*/
public void edit(Fish fish) throws NonexistentEntityException, RollbackFailureException, Exception {
try {
utx.begin();
fish = em.merge(fish);
utx.commit();
} catch (NotSupportedException | SystemException | RollbackException |
HeuristicMixedException | HeuristicRollbackException | SecurityException | IllegalStateException ex) {
try {
utx.rollback();
} catch (IllegalStateException | SecurityException | SystemException re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
String msg = ex.getLocalizedMessage();
if (msg == null || msg.length() == 0) {
Integer id = fish.getId();
if (findFish(id) == null) {
throw new NonexistentEntityException("The fish with id " + id + " no longer exists.");
}
}
throw ex;
}
}

/**
* Delete the record that matched the primary key. Verify that the record exists before deleting it.
*
* @param id
* @throws NonexistentEntityException
* @throws RollbackFailureException
* @throws Exception
*/
public void destroy(Integer id) throws NonexistentEntityException, RollbackFailureException, Exception {
try {
utx.begin();
Fish fish;
try {
fish = em.getReference(Fish.class, id);
fish.getId();
} catch (EntityNotFoundException enfe) {
throw new NonexistentEntityException("The fish with id " + id + " no longer exists.", enfe);
}
em.remove(fish);
utx.commit();
} catch (NotSupportedException | SystemException | NonexistentEntityException | RollbackException | HeuristicMixedException | HeuristicRollbackException | SecurityException | IllegalStateException ex) {
try {
utx.rollback();
} catch (IllegalStateException | SecurityException | SystemException re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
}
}

/**
* Return all the records in the table
*
* @return
*/
public List<Fish> findFishEntities() {
return findFishEntities(true, -1, -1);
}

/**
* Return some of the records from the table. Useful for paginating.
*
* @param maxResults
* @param firstResult
* @return
*/
public List<Fish> findFishEntities(int maxResults, int firstResult) {
return findFishEntities(false, maxResults, firstResult);
}

/**
* Either find all or find a group of fish
*
* @param all True means find all, false means find subset
* @param maxResults Number of records to find
* @param firstResult Record number to start returning records
* @return
*/
private List<Fish> findFishEntities(boolean all, int maxResults, int firstResult) {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Fish.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
}

/**
* Find a record by primary key
*
* @param id
* @return
*/
public Fish findFish(Integer id) {
return em.find(Fish.class, id);
}

/**
* Return the number of records in the table
*
* @return
*/
public int getFishCount() {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
Root<Fish> rt = cq.from(Fish.class);
cq.select(em.getCriteriaBuilder().count(rt));
Query q = em.createQuery(cq);
System.out.println("fish count: " + ((Long) q.getSingleResult()).intValue());
return ((Long) q.getSingleResult()).intValue();
}
}

You are now ready to use this controller class in your JPA/CDI project.

Read the original blog entry...

More Stories By Ken Fogel

In 1980 I bought for myself the most wonderful toy of the day, the Apple ][+. Obsession followed quickly and by 1983 I was writing software for small and medium sized businesses in Montreal for both the Apple and the IBM PC under the company name Omnibus Systems. In the evenings I taught continuing education courses that demystified the computer to the first generation of workers who found themselves with their typewriter on the scrap heap and a PC with WordStar taking its place.

In 1990 I was invited to join the faculty at Dawson College in the Computer Science Technology program. When I joined the program the primary language was COBOL and my responsibility was to teach small systems languages such as BASIC and C/C++.

Today I am now the chairperson and program coordinator of the Computer Science Technology program at Dawson. The program's primary language is Java and the focus is on enterprise programming.

I like to write about the every day problems my students and I face in using various languages and platforms to get the job done. And from time to time I stray from the path and write about what I plan to do, what I actually get around to doing, and what I imagine I am doing.

@omniprof

@ThingsExpo Stories
As data explodes in quantity, importance and from new sources, the need for managing and protecting data residing across physical, virtual, and cloud environments grow with it. Managing data includes protecting it, indexing and classifying it for true, long-term management, compliance and E-Discovery. Commvault can ensure this with a single pane of glass solution – whether in a private cloud, a Service Provider delivered public cloud or a hybrid cloud environment – across the heterogeneous enter...
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
"We view the cloud not as a specific technology but as a way of doing business and that way of doing business is transforming the way software, infrastructure and services are being delivered to business," explained Matthew Rosen, CEO and Director at Fusion, in this SYS-CON.tv interview at 18th Cloud Expo (http://www.CloudComputingExpo.com), held June 7-9 at the Javits Center in New York City, NY.
The Founder of NostaLab and a member of the Google Health Advisory Board, John is a unique combination of strategic thinker, marketer and entrepreneur. His career was built on the "science of advertising" combining strategy, creativity and marketing for industry-leading results. Combined with his ability to communicate complicated scientific concepts in a way that consumers and scientists alike can appreciate, John is a sought-after speaker for conferences on the forefront of healthcare science,...
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, discussed the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
In his session at Cloud Expo, Alan Winters, U.S. Head of Business Development at MobiDev, presented a success story of an entrepreneur who has both suffered through and benefited from offshore development across multiple businesses: The smart choice, or how to select the right offshore development partner Warning signs, or how to minimize chances of making the wrong choice Collaboration, or how to establish the most effective work processes Budget control, or how to maximize project result...
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
IoT is rapidly becoming mainstream as more and more investments are made into the platforms and technology. As this movement continues to expand and gain momentum it creates a massive wall of noise that can be difficult to sift through. Unfortunately, this inevitably makes IoT less approachable for people to get started with and can hamper efforts to integrate this key technology into your own portfolio. There are so many connected products already in place today with many hundreds more on the h...
DXWorldEXPO LLC announced today that ICC-USA, a computer systems integrator and server manufacturing company focused on developing products and product appliances, will exhibit at the 22nd International CloudEXPO | DXWorldEXPO. DXWordEXPO New York 2018, colocated with CloudEXPO New York 2018 will be held November 11-13, 2018, in New York City. ICC is a computer systems integrator and server manufacturing company focused on developing products and product appliances to meet a wide range of ...
JETRO showcased Japan Digital Transformation Pavilion at SYS-CON's 21st International Cloud Expo® at the Santa Clara Convention Center in Santa Clara, CA. The Japan External Trade Organization (JETRO) is a non-profit organization that provides business support services to companies expanding to Japan. With the support of JETRO's dedicated staff, clients can incorporate their business; receive visa, immigration, and HR support; find dedicated office space; identify local government subsidies; get...
René Bostic is the Technical VP of the IBM Cloud Unit in North America. Enjoying her career with IBM during the modern millennial technological era, she is an expert in cloud computing, DevOps and emerging cloud technologies such as Blockchain. Her strengths and core competencies include a proven record of accomplishments in consensus building at all levels to assess, plan, and implement enterprise and cloud computing solutions. René is a member of the Society of Women Engineers (SWE) and a m...
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Archi...
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, discussed how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team at D...
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abilit...
Organizations planning enterprise data center consolidation and modernization projects are faced with a challenging, costly reality. Requirements to deploy modern, cloud-native applications simultaneously with traditional client/server applications are almost impossible to achieve with hardware-centric enterprise infrastructure. Compute and network infrastructure are fast moving down a software-defined path, but storage has been a laggard. Until now.
Digital Transformation is much more than a buzzword. The radical shift to digital mechanisms for almost every process is evident across all industries and verticals. This is often especially true in financial services, where the legacy environment is many times unable to keep up with the rapidly shifting demands of the consumer. The constant pressure to provide complete, omnichannel delivery of customer-facing solutions to meet both regulatory and customer demands is putting enormous pressure on...
The best way to leverage your CloudEXPO | DXWorldEXPO presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering CloudEXPO | DXWorldEXPO will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at CloudEXPO. Product announcements during our show provide your company with the most reach through our targeted audienc...
@DevOpsSummit at Cloud Expo, taking place November 12-13 in New York City, NY, is co-located with 22nd international CloudEXPO | first international DXWorldEXPO and will feature technical sessions from a rock star conference faculty and the leading industry players in the world.
DXWorldEXPO LLC announced today that the upcoming DXWorldEXPO | CloudEXPO New York event will feature 10 companies from Poland to participate at the "Poland Digital Transformation Pavilion" on November 12-13, 2018.