schuchert - jpa tutorial 1 - getting started

8/3/2019 Schuchert - JPA Tutorial 1 - Getting Started

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Table of ContentsIntroduction

JPA Tutorial 1: Background

JPA Initial Setup

Eclipse Project Setup

Persistence Unit Configuration

Create Your First Entit

Add an Embedded Entit

Add an Entit ith a One to Man

Relationship

Make a Relationship Bi-Directional

Eercises

Entire Source Base

FAQ

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eig a eie i,ceaig i-e eiie ad

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T ih a daabae ig JPA, e eed a Entit Manager. Befe e ca d ha, e eed ceae a EntitManager Factor.

T acie a Entit Manager Factor, e e he ca java.persistence.Persistence. I ead a fie caed eiece. i he META-INF diec. I he ceae he aed Entit Manager Factor, hich cee

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C Entit Manager Entit Manager Factor :

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Term Description

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T JPA. T ' EMF("N") "N". T eie persistence.ml META-INF.

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JPA Initial SetupT J 5 (JDK 1.5) E 3.2 . T ' . W I , ' ... ' .

Noe: W . JPA. Y JEE . F , JB EJB3E , ' 150+ .

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Setup the JDK & Eclipse1. I JSE 5.2. E . F I C:/.

Etract Jar FilesE . I I C:/, I C://--3.4.0.GA

C://--3.4.0.GAC://--3.3.1.GAC://-1.9.0-3C://-3.1.1C://4-1.5.8

Eclipse Project Setup N .

Create Initial Project1. S .

2. W , . I C:\\JAE3. T I , .

3. C W

User LibrarW , . O , . T . W .1. P Windo:Pefeence2. N Jaa:Bild Pah:Ue Libaie3. C Ne4. E JPA_JSE OK

N . F , :1. S JPA_JSE ( , ' , UI

)2. C Add JAR...3. N 4. S 5. C Open6. R .

H ' ( ' C:/):C://--3.3.1.GA///-2.7.6. C://--3.3.1.GA///--3.1. C://--3.3.1.GA///4-1.6.1. C://--3.3.1.GA///-3.4.GA. C://--3.3.1.GA/3.

C:/-3.1.1//--5.0-2. C:/-3.1.1//4-1.2.12. C:/--3.4.0.GA/-. C:/-1.9.0-3///. C:/--3.4.0.GA/-. C:/--3.4.0.GA//--. C:/4-1.5.8/4--1.5.8. C:/4-1.5.8/4--1.5.8.

Create Java Project N J . W' :1. P File Ne:Pojec2. S Jaa Pojec Ne3. E : JpaToial1, I .





4. Make e "Ceae ne pojec in okpace" i eleced.5. Make e he JRE eleced i 1.5.. If a 1.5 JRE doe no ho in he li, o can add i hogh Windo-

>Pefeence->JAVA->Inalled JRE'.6. Selec "Ceae epaae oce and op folde"7. Click "finih"

Ceae flde ad ackage

1. Epand o pojec JpaToial12. Selec he c folde 3. Righ-click, elec ne:Folde

4. Ene he name META-INF5. Click Finih6. Selec he c folde again7. Righ-click, elec ne:Package8. Ene he name eni9. Click on Finih10. Selec he Toia1 pojec again11. Righ-click, elec ne:Soce Folde12. Ene he name e13. Click Finih14. Selec he e folde 15. Righ-click, elec ne:Package16. Ene he name eni

Add Reied LibaieWe no need o add o libaie. One ill be he e-defined liba e ceaed aboe. The econd ill be JUni 4..

1. Edi he pojec popeie. Selec o pojec (e.g. JpaToial1) and eihe pe al-eneo igh-click and elec popeie.

2. Selec Jaa Bild Pah3. Click on he Libaie ab4. Click on Add Liba5. Selec Ue Libaie and click Ne6. Selec JPA_JSE b clicking on he checkbo7. Click OK 8. Click on Add Liba again9. Click on JUni10. Click Ne

11. In he pll-don li, elec JUni 412. Click Finih13. Click OK

Sideba The JPA pecificaion a ha in a managed enionmen (ead a nning in he conaine), o do no need o li o eni clae in he peience.ml (hi i coming p). When o'e ing JPA in a JSE enionmen, hi i nogaaneed. In all of hee eample, e'e ing he hibenae implemenaion of he JEE Eni Manage. I poide hefncionali of aomaicall egieing all of o eniie iho o haing o eplicil li hem. Hoee, if ohappen o hae a pace in o cla pah, i appea o fail.

If o folloed he incion aboe, o'll hae he folloing dieco: C:/Wokpace/JpaAndEjb3/JpaToial1.

Unde ha dieco ill be a bin dieco hee o compiled cla file eide. Hibenae ill look in hi dieco andfind all clae ha ae eniie (denoed ih @Eni) and add hoe o o peien ni. In he fi eion of hioial, I ecommended he folloing name: C:/Wokpace/Jpa And Ejb3/Toial 1. When I an he die pogam,hibenae a nable o aomaicall find he bin dieco, I ame hi a becae of he pace in he name. Ichanged he name b emoing all of he pace and he poblem en aa.

Peiece Ui CfigaiWe no need o ceae he Peien Uni definiion. Ceae a file called peience.ml in he c/META-INF diecoih he folloing conen:





persistence.ml

<persistence>

<persistence-unit name="examplePersistenceUnit"

transaction-type="RESOURCE_LOCAL">

<properties>

<propert name="hibernate.show_sql" value="false" />

<propert name="hibernate.format_sql" value="false" />

<propert name="hibernate.connection.driver_class"

value="org.hsqldb.jdbcDriver" />

<propert name="hibernate.connection.url"

value="jdbc:hsqldb:mem:mem:aname" />

<propert name="hibernate.connection.username" value="sa" />

<propert name="hibernate.dialect"

value="org.hibernate.dialect.HSQLDialect" />

<propert name="hibernate.hbm2ddl.auto" value="create" />

</properties>

</persistence-unit>

</persistence>

The Steps1. Epand o pojec (JpaTutorial1)2. Selec he src/META-INF dieco

3. Righ click and elec ne:File4. Ene persistence.ml fo he name and pe Finish (Noe: all loecae. I on' make a diffeence on Windo

XP b i ill on Uni.)5. Cop he conen (aboe) ino he file and ae i.

Ve rif This Works1. Selec he test2. Righ-click on entit and elec ne:Class3. Ene PersonTest and click Finish4. Ene he eample code belo:

package entity; import

javax.persistence.EntityManager ;import javax.persistence.EntityManagerFactory ;import javax.persistence.Persistence; import org.apache.log4j.BasicConfigurator ;import org.apache.log4j.Level;import org.apache.log4j.Logger;

import org.junit.After;import org.junit.Before;import org.junit.Test; public class PersonTest { private EntityManagerFactory emf;

private EntityManager em;

@Before

public void initEmfAndEm() {BasicConfigurator.configure();

Logger.getLogger("org").setLevel(Level.ERROR);

emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");em = emf.createEntityManager();

@After public void cleanup() {

em.close();





@Test

public void emptyTest() {

1. When o'e finihed and i all compile, igh-click ihin he oce pane, elec Rn A:JUni Te2. Yo hold ee all geen3. If o do no, commen o he folloing line and eie he conole op

Logger.getLogger("org").setLevel(Level.ERROR);

Create Your First EntitFo hi eample e'll e a "op-don" appoach. Thi mean e'll ceae a Plain Old Jaa Objec (POJO) ih omeannoaion o indicae ho e an JPA o pei i. We'e leing he EniManage ake cae of ceaing he able inhe daabae fo .

Create a Simple Class

The folloing cla conain eehing o need o begin peiing i o a daabae:

Peon.jaa

package entity;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue ;

import javax.persistence.Id;

@Entit

public class Person {

@Id

@GeneratedValue

private int id;

private String firstName;

private char middleInitial;

private String lastName;

private String streetAddress1; private String streetAddress2;

private String city;

private String state;

private String zip;

public Person() {

public Person(final String fn, final char mi, final String ln,

final String sa1, final String sa2, final String city,

final String state, final String zip) {

setFirstName(fn);

setMiddleInitial(mi);

setLastName(ln);

setStreetAddress1(sa1);setStreetAddress2(sa2);

setCity(city);

setState(state);

setZip(zip);

public String getCity() {

return city;

public void setCity(final String city) {

this.city = city;





en firstName;

pblic oid setFirstName(final Sing firstName) {

hi.firstName = firstName;

pblic in getId() {

en id;

pblic oid setId(final in id) { hi.id = id;

pblic Sing getLastName() {

en lastName;

pblic oid setLastName(final Sing lastName) {

hi.lastName = lastName;

pblic cha getMiddleInitial() {

en middleInitial;

pblic oid setMiddleInitial(final cha middleInitial) {

hi.middleInitial = middleInitial;

pblic Sing getState() {

en state;

pblic oid setState(final Sing state) {

hi.state = state;

pblic Sing getStreetAddress1() {

en streetAddress1;

pblic oid setStreetAddress1(final Sing streetAddress1) {

hi.streetAddress1 = streetAddress1;

pblic Sing getStreetAddress2() {

en streetAddress2;

pblic oid setStreetAddress2(final Sing streetAddress2) {


pblic Sing getZip() { en zip;

pblic oid setZip(final Sing zip) {

hi.zip = zip;

Update persistence.m l Noe, fo o configaion hi ep i opional.

If o e libaie poided ecliel b JBo and Compan, hen o do no need o pdae o peience.ml. If o ae ing anohe endo o o an o make e ha o olion ill ok egadle of o peience

poide, add he folloing line o o peience.ml:





<class> entity.Person </class>

Y daed eiece. i :

<persistence>




<properties>







<propert name="hibernate.connection.username" value="sa" />



<propert name="hibernate.hbm2ddl.auto" value="create" />

</properties>

</persistence-unit>

</persistence>

Inserting and Quering N e eed dae i e ca, Pe.jaa. We i hae i ie ee, e ad eif ha he ee e ceaed ae i he daabae:PersonTest.jaa

package entity; import static org.junit.Assert.assertEquals;import static org.junit.Assert.assertTrue; import java.util.List;

import javax.persistence.EntityManager ;import javax.persistence.EntityManagerFactory ;import javax.persistence.Persistence; import org.apache.log4j.BasicConfigurator ;import org.apache.log4j.Level;import org.apache.log4j.Logger;import org.junit.After;import org.junit.Before;import org.junit.Test; public class PersonTest { private final Person p1 = new Person("Brett", 'L', "Schuchert", "Street1",

"Street2", "City", "State", "Zip");

private final Person p2 = new Person("FirstName", 'K', "LastName", "Street1", "Street2", "City", "State", "Zip");

private EntityManagerFactory emf; private EntityManager em;

@Before public void initEmfAndEm() {

BasicConfigurator.configure(); Logger.getLogger("org").setLevel(Level.ERROR);

emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");em = emf.createEntityManager();





pblic oid cleanup()

em.close();

@SppeWaning("unchecked")

@Test

pblic oid insertAndRetrieve()

em.getTransaction().begin();

em.persist(p1);

em.persist(p2);

em.getTransaction().commit();

final Li<Person> list = em.createQuer("select p from Person p")

.getResultList();

assertEquals(2, list.sie());

fo (Person current : list)

final Sing firstName = current.getFirstName();

assertTrue(firstName.equals("Brett")

firstName.equals("FirstName"));

Re-run this test (the short-cut for this is Ctrl-Fll). Verif that everthing is green.

Add an Embedded EntitWhen we created Person we directl included address information into them. This is alright, but what if we want to useAddress in another class? Let's introduce a new entit, Address, and make it embedded. This means its fields will end upas columns in the table of the entit that contains it.

First, we'll create Address:

Address.jaa

package entit;

impo java.persistence.Embeddable;

@Embeddable

pblic cla Address piae Sing streetAddress1;

piae Sing streetAddress2;

piae Sing cit;

piae Sing state;

piae Sing ip;

pblic Address()

pblic Address(final Sing sa1, final Sing sa2, final Sing cit,

final Sing state, final Sing ip)

setStreetAddress1(sa1);


setCit(cit);

setState(state);setZip(ip);

pblic final Sing getCit()

en cit;

pblic final oid setCit(final Sing cit)

hi.cit = cit;

pblic final Sing getState()

en state;





public final void setState(final String state) {

this.state = state;

public final String getStreetAddress1() {

return streetAddress1;

public final void setStreetAddress1(final String streetAddress1) {

this.streetAddress1 = streetAddress1;

public final String getStreetAddress2() {

return streetAddress2;

public final void setStreetAddress2(final String streetAddress2) {

this.streetAddress2 = streetAddress2;

public final String getZip() {

return zip;

public final void setZip(final String zip) {

this.zip = zip;

Net, e need to update Person (doing so ill cause our unit test class to no longer compile):Person.jaa

package entity;

import javax.persistence.Embedded;




@Entit public class Person {

@Id

@GeneratedValue

int id;




@Embedded

private Address address;

public Person() {


final Address address) {

setFirstName(fn);


setLastName(ln);

setAddress(address);

public String getFirstName() {

return firstName;

public void setFirstName(final String firstName) {

this.firstName = firstName;





pblic in getId() {

en id;

pblic oid setId(final in id) {

hi.id = id;

pblic Sing getLastName() {

en lastName;

pblic oid setLastName(final Sing lastName) {

hi.lastName = lastName;

pblic cha getMiddleInitial() {

en middleInitial;

pblic oid setMiddleInitial(final cha middleInitial) {

hi.middleInitial = middleInitial;

pblic final Address getAddress() {

en address;

pblic final oid setAddress(final Address address) {

hi.address = address;

Se enogh, if o eie PeonTe.jaa, i no longe compile. Befoe e go an fhe, le' pdae i o ge i ocompile and hen eif ha he ni e ill pa.

Replace he folloing o line:

piae final Person p1 = ne Person("Brett", 'L', "Schuchert", "Street1",

"Street2", "City", "State", "Zip");

piae final Person p2 = ne Person("FirstName", 'K', "LastName",

"Street1", "Street2", "City", "State", "Zip");

ih he folloing fo line

piae final Address a1 = ne Address("A Rd.", "", "Dallas", "TX", "75001"

piae final Person p1 = ne Person("Brett", 'L', "Schuchert", a1);

piae final Address a2 = ne Address("B Rd.", "S2", "OkC", "OK", "73116")

piae final Person p2 = ne Person("FirstName", 'K', "LastName", a2);

Ren o e (Ctrl-F11) and make e eehing i all geen.

Ne, e an o eif ha he adde e pei i in he daabae. Updae he ni e mehod a follo:

PersonTest#insertAndRetriee


@Test

pblic oid insertAndRetrieve() {


em.persist(p1);

em.persist(p2);






final List<Person> list = em.createQuer("select p from Person p")

.getResultList();


for (Person current : list)

final String firstName = current.getFirstName();

final String streetAddress1 = current.getAddress()

.getStreetAddress1();



assertTrue(streetAddress1.equals("A Rd.")

streetAddress1.equals("B Rd."));

Run our program and make sure it's all green.

Add an Entit with a One to Man Relationship Now we'll make a compan. In this first tutorial we're keeping things simple so we'll just create a Compan that has a 1 toman relationship with People, who are its emploees:

Compan.java

package entit;

import java.util.ArraList;

import java.util.Collection;

import java.persistence.Embedded;

import java.persistence.Entit;

import java.persistence.GeneratedValue ;

import java.persistence.Id;

import java.persistence.OneToMan;

@Entit

public class Compan

@Id

@GeneratedValue

int id; private String name;

@Embedded


@OneToMan

private Collection<Person> emploees;

public Compan()

public Compan(final String name, final Address address,

final Collection<Person> emploees)

setName(name);


setEmploees(emploees);

public Address getAddress()

return address;

public void setAddress(final Address address)

this.address = address;

public Collection<Person> getEmploees()

if (emploees == null)

emploees = new ArraList<Person>();

return em lo ees





pblic oid setEmployees(final Collecion<Person> employees) {

hi.employees = employees;

pblic in getId() {

en id;

pblic oid setId(final in id) {

hi.id = id;

pblic Sing getName() {

en name;

pblic oid setName(final Sing name) {

hi.name = name;

pblic oid hire(final Person p) {

getEmployees().add(p);

pblic oid fire(final Person p) {getEmployees().remove(p);

Faco o Common Te CodeWe have some common initialiation we can move up into a base since we are going to have two tests classes,PersonTest and CompanTest:TestBase.jaa

package entity;

impo javax.persistence.EntityManager ;impo javax.persistence.EntityManagerFactory ;

impo javax.persistence.Persistence;

impo org.apache.log4j.BasicConfigurator ;

impo org.apache.log4j.Level;

impo org.apache.log4j.Logger;

impo org.junit.After;

impo org.junit.Before;

pblic cla TestBase {

poeced EntityManagerFactory emf;

poeced EntityManager em;

pblic TestBase() {

pe();

@Before

pblic oid initEmfAndEm() {

BasicConfigurator.configure();

Logge.getLogger("org").setLevel(Leel.ERROR);

emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");

em = emf.createEntityManager();

@After

pblic oid cleanup() {

em.close();





.

"select c from Company c where c.name=?1").setParameter(1,

"The Company").getSingleResult();

assertEquals("D Rd.", foundCompany.getAddress().getStreetAddress1());

// Note, e do not need an assert. Wh? the method getSingleResult()

// ill thro an eception if there is not eactl one

// object found. We'll research that in the second JPA tutorial.

Run this unit test and make sure it is all green before going on (right-click in the source pane, select Run As:JUnit Test)

If you'd like to run all of your tests, right-click on the test folder, select Run As:JUnit Test and eclipse will execute all oyour tests classes' test methods.

Hie ome peopleWe need to create some people and add them to the company. The PersonTest class already has some people. Rather than re-creating new people, let's update PersonTest to make those fields available. Update the a1, p1, a2, and p2 fieldsas follows:

public static List<Person> generatePersonObjects() {

final List<Person> people = new ArraList<Person>();

final Address a1 = new Address("A Rd.", "", "Dallas", "TX", "75001");

final Person p1 = new Person("Brett", 'L', "Schuchert", a1);

final Address a2 = new Address("B Rd.", "S2", "OkC", "OK", "73116"); final Person p2 = new Person("FirstName", 'K', "LastName", a2);

people.add(p1);

people.add(p2);

return people;

You will also need to update the beginning of the method insertAndRetrieve from:


em.persist(p1);

em.persist(p2);


to:

final List<Person> people = generatePersonObjects();


for (Person p : people) {

em.persist(p);


Now we'll add a new test into CompanyTest to verify that we can hire people:

@SuppressWarnings("unchecked")

@Test

public void createCompanyAndHirePeople() {

final Company c1 = new Company();

c1.setName("The Company");

c1.setAddress(new Address("D Rd.", "", "Paris", "TX", "77382"));

List<Person> people = PersonTest.generatePersonObjects();

for (Person p : people) {

c1.hire(p);






for (Person p : people) {em.persist(p);

em.persist(c1);em.getTransaction().commit();

final List<Person> list = em.createQuery("select p from Person p")

.getResultList();assertEquals(2, list.size());

final Company foundCompany = (Company) em.createQuery(


"The Company").getSingleResult();assertEquals(2, foundCompany.getEmployees().size());

Update persistence.m lAgain, gien o enionmen, hi ep i opional.

persistence.ml

<persistence>




<class> entity.Company </class>

<properties>







<propert name="hibernate.connection.username"

value="sa" />



<propert name="hibernate.hbm2ddl.auto"

value="create" />

</properties>

</persistence-unit>

</persistence>

Make e eehing compile and n geen.

Make a Relationship Bi-Directional No e'e going o make e he Peon kno he Compan fo hich i ok. Thi i he "one" ide of a one oman elaionhip. We need o eplicil e hi ale and map i. We alo need o pdae he Compan @OneToManelaionhip o ha he Eni Manage kno i i a bi-diecional elaionhip ahe han j o nidiecionalelaionhip.

Fi e need o pdae Peon:Person.java


/** * Thi elaionhip i opional. Thi mean he daabae ill allo hi* elaionhip o be nll. I n o ha e i he defal ale o * e onl pecif i o docmen i eience.*/

@ManyToOne(optional = true) private Company job;

public Company getJob() {





Finall, we'll update CompanTest in several stages:

First, add a utilit method to retrieve companies b name:

piae Company findCompanyNamed(final EntityManager em, Sing name) {

en (Company) em.createQuery(

"select c from Company c where c.name=?1")

.setParameter(1, name).getSingleResult();

Add another support method to create a compan and hire a few people: piae Company createCompanyWithTwoEmployees() {

final Company c1 = ne Company();


c1.setAddress(ne Address("D Rd.", "", "Paris", "TX", "77382"));

final Li<Person> people = PersonTest.generatePersonObjects();

fo (Person p : people) {

c1.hire(p);



em.persist(p);

em.persist(c1);


en c1;

The method createCompan used to directl lookup a compan b name. Update the test method to use this privatemethod b changing this line:




to:

final Company foundCompany = findCompanyNamed(em, "The Company");

Update the method createCompanAndHirePeopl b using the support method createCompanWithTwoEmploees():


@Test

pblic oid createCompanyAndHirePeople() {

createCompanyWithTwoEmployees();

final Li<Person> list = em.createQuery("select p from Person p")

.getResultList();

assertEquals(2, list.size());




assertEquals(2, foundCompany.getEmployees().size());

Finall, add an additional unit test to hire and fire people:

@Test

pblic oid hireAndFire() {

final Company c1 = createCompanyWithTwoEmployees();








c1.fire(p);

em.persist(c1);




Make e eehing compile and i geen.

Eecie

QeionDecibe ha he @Eni annoaion mean o a cla.Decibe ha he @Id annoaion mean o a cla.Decibe ha he @GeneaedVale mean o a claDecibe he diffeence beeen @Embeddable and @EmbeddedIn he peio ecion e menioned ing mappedB o le he conaine kno hi a a bi-diecional elaionhipinead of a nidiecional elaionhip. Wha doe hi een mean? Da an inance diagam ha old eplain hidiffeence.

Ne ClaRigh no he elaionhip beeen Peon and Compan i diec. Le' make ha a lile le diec. The Peon holdno hae a Job ih a ile, ala and emploeeId. The compan ill ha emploee a befoe. Thi pice decibe he

befoe and afe elaionhip.

In ode o efaco o he [aboe] "afe" pice conide ome of he folloing adice:

Create JobCeae a cla, Job, ih he folloing aibe:in idSing ile

Sing SalaSing emploeeNmbe Compan companPeon peon (added - fi diagram )

Update EmploeeThe Peon cla hold no longe hae a Compan aibe. Inead i ha a Job aibe.

Update CompanUpdae Compan.hie(). Change he ignae o ake a peon, ile, ala. I ill hen ceae he job, geneae anemploeeId, and e p all he elaionhip and en he job.

Updae he Compan.fie() a necea.

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Enie Soce BaeAddress.jaa

package entity;

impo javax.persistence.Embeddable;

@Embeddable

pblic cla Address {



piae Sing city;

piae Sing state;

piae Sing zip;

pblic Address() {

pblic Address(final Sing sa1, final Sing sa2, final Sing city, final Sing state, final Sing zip) {



setCity(city);

setState(state);

setZip(zip);

pblic final Sing getCity() {

en city;

pblic final oid setCity(final Sing city) {

hi.city = city;

pblic final Sing getState() {

en state;

pblic final oid setState(final Sing state) {

hi.state = state;

pblic final Sing getStreetAddress1() {

en streetAddress1;

pblic final oid setStreetAddress1(final Sing streetAddress1) {


pblic final Sing getStreetAddress2() {

en streetAddress2;

pblic final oid setStreetAddress2(final Sing streetAddress2) {


pblic final Sing getZip() {

en zip;





public final void setZip(final String zip) {

this.zip = zip;

Person.jaa

package entity;





import javax.persistence.ManyToOne;

@Entit


@Id

@GeneratedValue

int id;




@ManyToOne(optional = true)

private Company job;

@Embedded


public Person() {


final Address address) {

setFirstName(fn);


setLastName(ln);


public String getFirstName() {

return firstName;

public void setFirstName(final String firstName) {

this.firstName = firstName;

public int getId() {

return id;

public void setId(final int id) {

this.id = id;

public String getLastName() {

return lastName;

public void setLastName(final String lastName) {

this.lastName = lastName;

public char getMiddleInitial() {

return middleInitial;

public void setMiddleInitial(final char middleInitial) {

this.middleInitial = middleInitial;





public final Address getAddress() {

return address;

public final void setAddress(final Address address) {


public Company getJob() {

return job;

public void setJob(Company job) {

this.job = job;

public boolean equals(final Object rhs) {

if (rhs instanceof Person) {

final Person other = (Person) rhs;

return other.getLastName().equals(getLastName())

&& other.getFirstName().equals(getFirstName())

&& other.getMiddleInitial() == getMiddleInitial();

return false;

public int hashCode() {

return getLastName().hashCode() * getFirstName().hashCode()

* getMiddleInitial();

Compan.java

package entity;

import java.util.ArrayList;

import java.util.Collection;





import javax.persistence.OneToMany;

@Entit

public class Company {

@Id

@GeneratedValue

int id;

private String name;

@Embedded private Address address;

@OneToMany(mappedBy = "job")

private Collection<Person> employees;

public Company() {

public Company(final String name, final Address address,

final Collection<Person> employees) {

setName(name);


setEmployees(employees);





public Address getAddress() {

return address;

public void setAddress(final Address address) {


public Collection<Person> getEmployees() {

if (employees == null) {

employees = new ArraList<Person>();

return employees;

public void setEmployees(final Collection<Person> newStaff) {

// fire everbod

final Collection<Person> clone = new ArraList<Person>(employees);

for (Person p : clone) {

fire(p);

for (Person p : newStaff) {

hire(p);

public int getId() {

return id;

public void setId(final int id) {

this.id = id;

public String getName() {

return name;

public void setName(final String name) {

this.name = name;

public void hire(final Person p) {

getEmployees().add(p);

p.setJob(this);

public void fire(final Person p) {

getEmployees().remove(p);

p.setJob(null);

TestBase.jaa

package entity;

import javax.persistence.EntityManager ;

import javax.persistence.EntityManagerFactory ;

import javax.persistence.Persistence;

import org.apache.log4j.BasicConfigurator ;

import org.apache.log4j.Level;

import org.apache.log4j.Logger;

import org.junit.After;

import org.junit.Before;





poeced EntityManagerFactory emf;

poeced EntityManager em;

pblic TestBase() {

pe();

@Before

pblic oid initEmfAndEm() {

BasicConfigurator.configure();

Logge.getLogger("org").setLevel(Leel.ERROR);

emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");

em = emf.createEntityManager();

@After

pblic oid cleanup() {

em.close();

CompanTest.java

package entity;

impo aic org.junit.Assert.assertEquals;

impo java.util.List;

impo javax.persistence.EntityManager ;

impo org.junit.Test;

pblic cla CompanyTest eend TestBase {

piae Company findCompanyNamed(final EntityManager em, Sing name) {

en (Company) em.createQuery(

"select c from Company c where c.name=?1")

.setParameter(1, name).getSingleResult();

@Test

pblic oid createCompany() {





em.persist(c1);



assertEquals("D Rd.", foundCompany.getAddress().getStreetAddress1());

// Note, e do not need an assert. Wh? the method getSingleResult() // ill thro an eception if there is not eactl one

// object found. We'll research that in the second JPA tutorial.

piae Company createCompanyWithTwoEmployees() {






c1.hire(p);





. .


em.persist(p);

em.persist(c1);


en c1;


@Test

pblic oid createCompanyAndHirePeople() {

createCompanyWithTwoEmployees();

final Li<Person> list = em.createQuery("select p from Person p")

.getResultList();

assertEquals(2, list.size());





@Test

pblic oid hireAndFire() { final Company c1 = createCompanyWithTwoEmployees();




c1.fire(p);

em.persist(c1);




PersonTest.jaa

package entity;

impo aic org.junit.Assert.assertEquals;

impo aic org.junit.Assert.assertTrue;

impo java.util.ArrayList;

impo java.util.List;

impo org.junit.Test;

pblic cla PersonTest eend TestBase {

pblic aic Li<Person> generatePersonObjects() { final Li<Person> people = ne AaLi<Person>();

final Address a1 = ne Address("A Rd.", "", "Dallas", "TX", "75001");

final Person p1 = ne Person("Brett", 'L', "Schuchert", a1);

final Address a2 = ne Address("B Rd.", "S2", "OkC", "OK", "73116");

final Person p2 = ne Person("FirstName", 'K', "LastName", a2);

people.add(p1);

people.add(p2);

en people;





@Test

pblic oid insertAndRetrieve()

final Li<Person> people = generatePersonObjects();


fo (Person p : people)

em.persist(p);


final Li<Person> list = em.createQuer("select p from Person p")

.getResultList();


fo (Person current : list)

final Sing firstName = current.getFirstName();

final Sing streetAddress1 = current.getAddress()

.getStreetAddress1();



assertTrue(streetAddress1.equals("A Rd.")

streetAddress1.equals("B Rd."));

FAQ

JPA Torial 1 - FAQ* What's the entit Manager? O . M @E. A / , ' . "Y "

Is hibernate using an in-memor database? H JPA. I . T H SQL.When do ou need a default constructor? S . I , . I (/), .

Annotations? A - - . T //. R . A '' (-, -, -).Compared to toplink: How are isolation levels handled? What kind of caching concerns do we have to worrabout? T .JEE source? D JB () B.Where does @Id go? (mehod or field?) I ' , JPA , ( ' '). I ' (I()), JPA , ' ' .Is there a reason @id is not private? B . (I )

When creating the job class, do we need equals() and hashcode()? In Compan.java there is a la-initialiation in getEmploees() . Wh? W , I (). L . T ( '' ).What's with the equals() method on Person? Y ' () ' . (-, , -, )How man times does it go to the database when ou have a one-to-man and ou retrieve the 'one' side. B, ('') , ( ' ) '' -- . Y =FT.EAGER (

). S ._=.Can ou turn off the 'caching' part of JPA? Y . L ' ' .How do ou know what ou set 'mappedB' to? U What happens if ou manipulate our objects outside of a transaction? I JSE , EM. S , , . I, , EM , .





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