From 14891191e18f7966f779e132c97f1fe7f0643d3f Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Wed, 24 Apr 2013 13:15:35 +0200
Subject: [PATCH] Bi-directional navigation
---
Doc/course.xml | 244 +++++++++++++-----
.../main/java/entity/company4/Employee.java | 71 +++++
.../src/main/java/entity/company4/Laptop.java | 63 +++++
.../main/java/entity/company4/Persist.java | 38 +++
.../java/entity/company4/hibernate.cfg.xml | 21 ++
.../main/java/entity/company5/Persist.java | 41 +++
.../java/entity/company5/hibernate.cfg.xml | 21 ++
.../java/entity/company5/model/Employee.java | 83 ++++++
.../java/entity/company5/model/Laptop.java | 64 +++++
9 files changed, 577 insertions(+), 69 deletions(-)
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company4/Employee.java
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company4/Laptop.java
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company4/Persist.java
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company4/hibernate.cfg.xml
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company5/Persist.java
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company5/hibernate.cfg.xml
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company5/model/Employee.java
create mode 100644 ws/eclipse/HibIntro/src/main/java/entity/company5/model/Laptop.java
diff --git a/Doc/course.xml b/Doc/course.xml
index 53a3ce009..be2229636 100644
--- a/Doc/course.xml
+++ b/Doc/course.xml
@@ -18648,20 +18648,23 @@ public class PersistUser {
<section xml:id="mappingEntities">
<title>Mapping entities</title>
- <para>In contrast to mapping an entity having components we may also
- persist relations between entities. We start with
- <classname>entity.company1.Employee</classname>s possibly having
- <classname>entity.company1.Laptop</classname>s assigned. So an
- employee may or may not have one device at its disposal.</para>
-
- <para>There may be other references to each laptop. So in contrast to
- our email component examples
- <classname>entity.company1.Laptop</classname> instances are
- identifiable database objects and hence entities. Therefore we have to
- add a <code>@OneToOne</code> annotation <coref
- linkend="laptopOneToOne"/>:</para>
-
- <programlisting>package entity.company1;
+ <section xml:id="mappingOneToOne">
+ <title>One to one</title>
+
+ <para>In contrast to mapping an entity having components we may also
+ persist relations between entities. We start with
+ <classname>entity.company1.Employee</classname>s possibly having
+ <classname>entity.company1.Laptop</classname>s assigned. So an
+ employee may or may not have one device at its disposal.</para>
+
+ <para>There may be other references to each laptop. So in contrast
+ to our email component examples
+ <classname>entity.company1.Laptop</classname> instances are
+ identifiable database objects and hence entities. Therefore we have
+ to add a <code>@OneToOne</code> annotation <coref
+ linkend="laptopOneToOne"/>:</para>
+
+ <programlisting>package entity.company1;
...
@Entity ...
public class Employee {
@@ -18680,10 +18683,10 @@ public class Employee {
private Laptop laptop;
...</programlisting>
- <para>Populating the database with data seems to be quite
- straightforward:</para>
+ <para>Populating the database with data seems to be quite
+ straightforward:</para>
- <programlisting>package entity.company1;
+ <programlisting>package entity.company1;
...
public class Persist1 {
...
@@ -18696,24 +18699,24 @@ public class Persist1 {
session.save(eve);
transaction.commit(); ...</programlisting>
- <para>This actually fails:</para>
+ <para>This actually fails:</para>
- <programlisting> <classname>org.hibernate.TransientObjectException</classname>:
+ <programlisting> <classname>org.hibernate.TransientObjectException</classname>:
object references an unsaved transient instance -
save the transient instance before flushing: <classname>entity.company1.Laptop</classname></programlisting>
- <para>There are at least two possible solutions:</para>
+ <para>There are at least two possible solutions:</para>
- <orderedlist>
- <listitem>
- <para>We may save the dependent transient
- <classname>entity.company1.Laptop</classname> instance along with
- the two <classname>entity.company1.Employee</classname> instances.
- There is no restriction regarding the order of these three save
- operations but they must happen within the same
- transaction:</para>
-
- <programlisting>package entity.company1;
+ <orderedlist>
+ <listitem>
+ <para>We may save the dependent transient
+ <classname>entity.company1.Laptop</classname> instance along
+ with the two <classname>entity.company1.Employee</classname>
+ instances. There is no restriction regarding the order of these
+ three save operations but they must happen within the same
+ transaction:</para>
+
+ <programlisting>package entity.company1;
...
public class Persist2 {
...
@@ -18728,17 +18731,17 @@ public class Persist2 {
session.save(superCoolGadget);
transaction.commit(); ...</programlisting>
- </listitem>
+ </listitem>
- <listitem>
- <para>Hibernate supports the <quote>persistence by
- reachability</quote> concept. Thus saving an
- <classname>entity.company1.Employee</classname> instance should
- save possibly referenced
- <classname>entity.company1.Laptop</classname> instances as
- well:</para>
-
- <programlisting>package entity.company2;
+ <listitem>
+ <para>Hibernate supports the <quote>persistence by
+ reachability</quote> concept. Thus saving an
+ <classname>entity.company1.Employee</classname> instance should
+ save possibly referenced
+ <classname>entity.company1.Laptop</classname> instances as
+ well:</para>
+
+ <programlisting>package entity.company2;
...
public class Employee {
...
@@ -18746,10 +18749,10 @@ public class Employee {
public Laptop getLaptop() { return laptop;}
...</programlisting>
- <para>No we do no longer have to care about referenced
- <classname>entity.company1.Laptop</classname>s:</para>
+ <para>No we do no longer have to care about referenced
+ <classname>entity.company1.Laptop</classname>s:</para>
- <programlisting>package entity.company2;
+ <programlisting>package entity.company2;
...
public class Persist {
...
@@ -18764,14 +18767,14 @@ public class Persist {
session.save(martin);
session.save(eve);
transaction.commit();...</programlisting>
- </listitem>
- </orderedlist>
+ </listitem>
+ </orderedlist>
- <para>After successfully inserting these three entities
- <personname>Eve Blix</personname> shall no longer be entitled to use
- her laptop. We thus decouple these two entities:</para>
+ <para>After successfully inserting these three entities
+ <personname>Eve Blix</personname> shall no longer be entitled to use
+ her laptop. We thus decouple these two entities:</para>
- <programlisting>package entity.company2;
+ <programlisting>package entity.company2;
public class LoadAndDeRegister {
...
final Transaction transaction = session.beginTransaction();
@@ -18781,29 +18784,132 @@ public class LoadAndDeRegister {
transaction.commit();</programlisting>
- <para>All three entities are still present in our database but the
- corresponding foreign key has been set to <code>NULL</code>.</para>
+ <para>All three entities are still present in our database but the
+ corresponding foreign key has been set to <code>NULL</code>.</para>
- <qandaset role="exercise">
- <title>One laptop per employee</title>
+ <qandaset role="exercise">
+ <title>One laptop per employee</title>
- <qandadiv>
- <qandaentry>
- <question>
- <para>Consider a company where each employee must have a
- laptop being assigned and modify the mapping in
- <classname>entity.company2.Employee</classname>
- accordingly.</para>
- </question>
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider a company where each employee must have a
+ laptop being assigned and modify the mapping in
+ <classname>entity.company2.Employee</classname>
+ accordingly.</para>
+ </question>
- <answer>
- <para>See <emphasis
- role="bold">@OneToOne(optional=false,...</emphasis> in
- <classname>entity.company3.Employee</classname>.</para>
- </answer>
- </qandaentry>
- </qandadiv>
- </qandaset>
+ <answer>
+ <para>See <emphasis
+ role="bold">@OneToOne(optional=false,...</emphasis> in
+ <classname>entity.company3.Employee</classname>.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="oneToOneBidirectionalNavigate">
+ <title>Bi-directional navigation</title>
+
+ <para>So far instances of
+ <classname>entity.company3.Laptop</classname> have no references to
+ their possible respective <quote>owner</quote>: A <abbrev
+ role="g">Java</abbrev> developer may navigate from
+ <classname>entity.company3.Employee</classname> to
+ <classname>entity.company3.Laptop</classname> via
+ <methodname>entity.company3.Employee.getLaptop()</methodname> but
+ there is no path back. This requirement may be implemented by
+ introducing a new property owner <coref
+ linkend="introduceOwnerBiDirect"/>:</para>
+
+ <programlisting>package entity.company4;
+...
+@Entity
+public class Laptop {
+
+ @OneToOne
+ public Employee getOwner() <co xml:id="introduceOwnerBiDirect"/> { return owner;}
+ public void setOwner(Employee owner) { this.owner = owner;}
+ Employee owner; ...</programlisting>
+
+ <para>We may insert suitable instances:</para>
+
+ <programlisting>package entity.company4;
+...
+public class Persist {
+...
+ final Employee martin = new Employee(123, "Martin Goik"),
+ eve = new Employee(140, "Eve Blix");
+
+ final Laptop superCoolGadget = new Laptop(2213),
+ g2 = new Laptop(2214),
+ g3 = new Laptop(2215); // Not being referenced later
+
+ martin.setLaptop(g2);
+ eve.setLaptop(superCoolGadget);
+ // Now only save the employee transients,
+ // superCoolGadget will be saved automatically due to
+ // CascadeType.ALL
+ session.save(martin);
+ session.save(eve);
+ session.save(g3);
+ transaction.commit();...</programlisting>
+
+ <para>This codes executes but does not yield a correct database
+ state:</para>
+
+ <programlisting>mysql> select * from Employee; select * from Laptop;
+| id | cname | staffNumber | laptop_id |
++----+-------------+-------------+-----------+
+| 1 | Martin Goik | 123 | 1 |
+| 2 | Eve Blix | 140 | 2 |
+
+| id | idNumber | owner_id |
++----+----------+----------+
+| 1 | 2214 | NULL | <emphasis role="bold"><-- Expectded to be 1 (Martin Goik)</emphasis>
+| 2 | 2213 | NULL | <emphasis role="bold"><-- Expectded to be 2 (Eve Blix)</emphasis>
+| 3 | 2215 | NULL |</programlisting>
+
+ <para>This problem is actually <abbrev role="g">pojo</abbrev>
+ related. In contrast to Container Managed Persistence (<abbrev
+ role="g">CMP</abbrev>) the <link linkend="gloss_JPA">JPA</link>
+ standard does not care about implementing bi directional navigation.
+ Instead this task is left to the user. We may change the setter on
+ the <classname>entity.company4.Employee</classname> side of the
+ relationship:</para>
+
+ <programlisting>package entity.company5.model;
+...
+public class Employee {
+
+@OneToOne(optional=false, cascade={CascadeType.ALL})
+ public Laptop getLaptop() { return laptop;}
+ public void setLaptop(final Laptop laptop) {
+ if (getLaptop() == laptop) {
+ return;
+ }
+ if (null != this.laptop) {
+ this.laptop.setOwner(null);
+ }
+ this.laptop = laptop;
+ if (null != this.laptop) {
+ this.laptop.setOwner(this);
+ }
+ } ...</programlisting>
+
+ <para>There is a database issue present here as well. Having just a
+ <code>@OneToOne</code> relationship it suffices to have just on
+ foreign key in our database. This is achieved by adding a
+ <code>mappedBy</code> attribute:</para>
+
+ <programlisting>package entity.company5.model;
+...
+public class Laptop {
+...
+@OneToOne (<emphasis role="bold">mappedBy="laptop"</emphasis>)
+ public Employee getOwner() { return owner;} ...</programlisting>
+ </section>
</section>
</chapter>
</part>
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company4/Employee.java b/ws/eclipse/HibIntro/src/main/java/entity/company4/Employee.java
new file mode 100644
index 000000000..208d8537e
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company4/Employee.java
@@ -0,0 +1,71 @@
+package entity.company4;
+
+import javax.persistence.CascadeType;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToOne;
+import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
+
+/**
+ *
+ * {@link Employee} instances related to {@link Department}
+ *
+ */
+@Entity
+@Table(uniqueConstraints={@UniqueConstraint(columnNames={"staffNumber"})})
+public class Employee {
+
+ @Id
+ @GeneratedValue
+ public Long getId() {return id;}
+ protected void setId(Long id) {this.id = id;}
+ private Long id;
+
+ public int getStaffNumber() { return staffNumber;}
+ public void setStaffNumber(int staffNumber) { this.staffNumber = staffNumber;}
+ int staffNumber = Integer.MIN_VALUE;
+
+ public String getCname() { return cname;}
+ public void setCname(String cname) { this.cname = cname;}
+ private String cname; // Common name
+
+ /**
+ * One laptop per {@link Employee}.
+ *
+ * @return Laptop "owned" by {@link Employee}.
+ */
+ @OneToOne(optional=false, cascade={CascadeType.ALL})
+ public Laptop getLaptop() { return laptop;}
+ public void setLaptop(Laptop laptop) {this.laptop = laptop;}
+ private Laptop laptop;// Workstation for employees.
+
+ protected Employee(){}
+
+ public Employee(final int staffNumber, final String cname) {
+ setStaffNumber(staffNumber);
+ setCname(cname);
+ }
+ @Override
+ public boolean equals(Object other) {
+ if (this == other) {
+ return true;
+ } else if (Integer.MIN_VALUE == getStaffNumber()) {
+ return false;
+ } else if (other instanceof Employee) {
+ final Employee that = (Employee) other;
+ return this.getStaffNumber() == that.getStaffNumber();
+ } else {
+ return false;
+ }
+ }
+ @Override
+ public int hashCode() {
+ if (Integer.MIN_VALUE == getStaffNumber()) {
+ return System.identityHashCode(this);
+ } else {
+ return getStaffNumber();
+ }
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company4/Laptop.java b/ws/eclipse/HibIntro/src/main/java/entity/company4/Laptop.java
new file mode 100644
index 000000000..e390f0c91
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company4/Laptop.java
@@ -0,0 +1,63 @@
+package entity.company4;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToOne;
+import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
+
+/**
+ *
+ * Laptops possibly being assigned to {@link Employee}
+ *
+ */
+@Entity
+@Table(uniqueConstraints={@UniqueConstraint(columnNames={"idNumber"})})
+public class Laptop {
+
+ @Id
+ @GeneratedValue
+ public Long getId() {return id;}
+ protected void setId(Long id) {this.id = id;}
+ private Long id;
+
+ /**
+ * @return The device's unique part number
+ */
+ public int getIdNumber() { return idNumber;}
+ public void setIdNumber(int idNumber) { this.idNumber = idNumber;}
+ int idNumber;
+
+ @OneToOne
+ public Employee getOwner() { return owner;}
+ public void setOwner(Employee owner) { this.owner = owner;}
+ Employee owner;
+
+ protected Laptop(){}
+
+ public Laptop(final int idNumber) {
+ setIdNumber(idNumber);
+ }
+ @Override
+ public boolean equals(Object other) {
+ if (this == other) {
+ return true;
+ } else if (Integer.MIN_VALUE == getIdNumber()) {
+ return false;
+ } else if (other instanceof Laptop) {
+ final Laptop that = (Laptop) other;
+ return this.getIdNumber() == that.getIdNumber();
+ } else {
+ return false;
+ }
+ }
+ @Override
+ public int hashCode() {
+ if (Integer.MIN_VALUE == getIdNumber()) {
+ return System.identityHashCode(this);
+ } else {
+ return getIdNumber();
+ }
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company4/Persist.java b/ws/eclipse/HibIntro/src/main/java/entity/company4/Persist.java
new file mode 100644
index 000000000..ae153a163
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company4/Persist.java
@@ -0,0 +1,38 @@
+package entity.company4;
+
+import hibintro.util.HibernateUtil;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+
+/**
+ * Persisting {@link Employee} possibly along with
+ * personal assigned laptops.
+ */
+public class Persist {
+ /**
+ * @param args not used.
+ */
+ public static void main(String[] args) {
+ final Session session = HibernateUtil.createSessionFactory("entity/company4/hibernate.cfg.xml").openSession();
+ {
+ final Transaction transaction = session.beginTransaction();
+ final Employee martin = new Employee(123, "Martin Goik"),
+ eve = new Employee(140, "Eve Blix");
+
+ final Laptop superCoolGadget = new Laptop(2213),
+ g2 = new Laptop(2214),
+ g3 = new Laptop(2215); // Not being referenced later
+
+ martin.setLaptop(g2);
+ eve.setLaptop(superCoolGadget);
+ // Now only save the employee transients,
+ // superCoolGadget will be saved automatically due to
+ // CascadeType.ALL
+ session.save(martin);
+ session.save(eve);
+ session.save(g3);
+ transaction.commit();
+ }
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company4/hibernate.cfg.xml b/ws/eclipse/HibIntro/src/main/java/entity/company4/hibernate.cfg.xml
new file mode 100644
index 000000000..b07752abc
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company4/hibernate.cfg.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!DOCTYPE hibernate-configuration PUBLIC
+ "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
+ "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
+
+<hibernate-configuration>
+ <session-factory >
+ <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
+ <property name="hibernate.connection.password">XYZ</property>
+ <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hdm</property>
+ <property name="hibernate.connection.username">hdmuser</property>
+ <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
+ <property name="hibernate.show_sql">false</property>
+ <property name="hibernate.format_sql">true</property>
+ <property name="hibernate.hbm2ddl.auto">update</property>
+
+ <mapping class="entity.company4.Laptop"/>
+ <mapping class="entity.company4.Employee"/>
+ </session-factory>
+</hibernate-configuration>
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company5/Persist.java b/ws/eclipse/HibIntro/src/main/java/entity/company5/Persist.java
new file mode 100644
index 000000000..92d009745
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company5/Persist.java
@@ -0,0 +1,41 @@
+package entity.company5;
+
+import hibintro.util.HibernateUtil;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+
+import entity.company5.model.Employee;
+import entity.company5.model.Laptop;
+
+/**
+ * Persisting {@link Employee} possibly along with
+ * personal assigned laptops.
+ */
+public class Persist {
+ /**
+ * @param args not used.
+ */
+ public static void main(String[] args) {
+ final Session session = HibernateUtil.createSessionFactory("entity/company5/hibernate.cfg.xml").openSession();
+ {
+ final Transaction transaction = session.beginTransaction();
+ final Employee martin = new Employee(123, "Martin Goik"),
+ eve = new Employee(140, "Eve Blix");
+
+ final Laptop superCoolGadget = new Laptop(2213),
+ g2 = new Laptop(2214),
+ g3 = new Laptop(2215); // Not being referenced later
+
+ martin.setLaptop(g2);
+ eve.setLaptop(superCoolGadget);
+ // Now only save the employee transients,
+ // superCoolGadget will be saved automatically due to
+ // CascadeType.ALL
+ session.save(martin);
+ session.save(eve);
+ session.save(g3);
+ transaction.commit();
+ }
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company5/hibernate.cfg.xml b/ws/eclipse/HibIntro/src/main/java/entity/company5/hibernate.cfg.xml
new file mode 100644
index 000000000..bbc11212f
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company5/hibernate.cfg.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!DOCTYPE hibernate-configuration PUBLIC
+ "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
+ "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
+
+<hibernate-configuration>
+ <session-factory >
+ <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
+ <property name="hibernate.connection.password">XYZ</property>
+ <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hdm</property>
+ <property name="hibernate.connection.username">hdmuser</property>
+ <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
+ <property name="hibernate.show_sql">false</property>
+ <property name="hibernate.format_sql">true</property>
+ <property name="hibernate.hbm2ddl.auto">update</property>
+
+ <mapping class="entity.company5.Laptop"/>
+ <mapping class="entity.company5.Employee"/>
+ </session-factory>
+</hibernate-configuration>
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Employee.java b/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Employee.java
new file mode 100644
index 000000000..4d0744658
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Employee.java
@@ -0,0 +1,83 @@
+package entity.company5.model;
+
+import javax.persistence.CascadeType;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToOne;
+import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
+
+
+/**
+ *
+ * {@link Employee} instances related to {@link Department}
+ *
+ */
+@Entity
+@Table(uniqueConstraints={@UniqueConstraint(columnNames={"staffNumber"})})
+public class Employee {
+
+ @Id
+ @GeneratedValue
+ public Long getId() {return id;}
+ protected void setId(Long id) {this.id = id;}
+ private Long id;
+
+ public int getStaffNumber() { return staffNumber;}
+ public void setStaffNumber(int staffNumber) { this.staffNumber = staffNumber;}
+ int staffNumber = Integer.MIN_VALUE;
+
+ public String getCname() { return cname;}
+ public void setCname(String cname) { this.cname = cname;}
+ private String cname; // Common name
+
+ /**
+ * One {@link Laptop} per {@link Employee}.
+ *
+ * @return {@link Laptop} "owned" by {@link Employee}.
+ */
+ @OneToOne(optional=false, cascade={CascadeType.ALL})
+ public Laptop getLaptop() { return laptop;}
+ public void setLaptop(final Laptop laptop) {
+ if (getLaptop() == laptop) {
+ return;
+ }
+ if (null != this.laptop) {
+ this.laptop.setOwner(null);
+ }
+ this.laptop = laptop;
+ if (null != this.laptop) {
+ this.laptop.setOwner(this);
+ }
+ }
+ private Laptop laptop;// Workstation for employees.
+
+ protected Employee(){}
+
+ public Employee(final int staffNumber, final String cname) {
+ setStaffNumber(staffNumber);
+ setCname(cname);
+ }
+ @Override
+ public boolean equals(Object other) {
+ if (this == other) {
+ return true;
+ } else if (Integer.MIN_VALUE == getStaffNumber()) {
+ return false;
+ } else if (other instanceof Employee) {
+ final Employee that = (Employee) other;
+ return this.getStaffNumber() == that.getStaffNumber();
+ } else {
+ return false;
+ }
+ }
+ @Override
+ public int hashCode() {
+ if (Integer.MIN_VALUE == getStaffNumber()) {
+ return System.identityHashCode(this);
+ } else {
+ return getStaffNumber();
+ }
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Laptop.java b/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Laptop.java
new file mode 100644
index 000000000..933c4292c
--- /dev/null
+++ b/ws/eclipse/HibIntro/src/main/java/entity/company5/model/Laptop.java
@@ -0,0 +1,64 @@
+package entity.company5.model;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToOne;
+import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
+
+
+/**
+ *
+ * Laptops possibly being assigned to {@link Employee}
+ *
+ */
+@Entity
+@Table(uniqueConstraints={@UniqueConstraint(columnNames={"idNumber"})})
+public class Laptop {
+
+ @Id
+ @GeneratedValue
+ public Long getId() {return id;}
+ protected void setId(Long id) {this.id = id;}
+ private Long id;
+
+ /**
+ * @return The device's unique part number
+ */
+ public int getIdNumber() { return idNumber;}
+ public void setIdNumber(int idNumber) { this.idNumber = idNumber;}
+ int idNumber;
+
+ @OneToOne (mappedBy="laptop")
+ public Employee getOwner() { return owner;}
+ protected void setOwner(Employee owner) { this.owner = owner;}
+ Employee owner;
+
+ protected Laptop(){}
+
+ public Laptop(final int idNumber) {
+ setIdNumber(idNumber);
+ }
+ @Override
+ public boolean equals(Object other) {
+ if (this == other) {
+ return true;
+ } else if (Integer.MIN_VALUE == getIdNumber()) {
+ return false;
+ } else if (other instanceof Laptop) {
+ final Laptop that = (Laptop) other;
+ return this.getIdNumber() == that.getIdNumber();
+ } else {
+ return false;
+ }
+ }
+ @Override
+ public int hashCode() {
+ if (Integer.MIN_VALUE == getIdNumber()) {
+ return System.identityHashCode(this);
+ } else {
+ return getIdNumber();
+ }
+ }
+}
\ No newline at end of file
--
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