Java/JPA/One to One Mapping
Содержание
BiDirection One To One Mappoing
<source lang="java">
File: Address.java import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Address {
@Id
private int id;
private String street;
private String city;
private String state;
private String zip;
@OneToOne(cascade=CascadeType.ALL)
private Student student;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getStreet() {
return street;
}
public void setStreet(String address) {
this.street = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
public String toString() {
return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
+ ", state: " + getState() + ", zip: " + getZip();
}
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception {
Class.forName("org.hsqldb.jdbcDriver");
Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
Statement st = conn.createStatement();
ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" });
while (mrs.next()) {
String tableName = mrs.getString(3);
System.out.println("\n\n\n\nTable Name: "+ tableName);
ResultSet rs = st.executeQuery("select * from " + tableName);
ResultSetMetaData metadata = rs.getMetaData();
while (rs.next()) {
System.out.println(" Row:");
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", ");
System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": ");
Object value = rs.getObject(i + 1);
System.out.println(" Column Value: "+value+"\n");
}
}
}
}
}
File: Main.java import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService");
static EntityManager em = emf.createEntityManager();
public static void main(String[] a) throws Exception {
em.getTransaction().begin();
Student student = new Student();
student.setName("Joe");
Address address = new Address();
address.setCity("city");
address.setStudent(student);
//em.persist(address);
student.setAddress(address);
em.persist(student);
em.flush();
em.getTransaction().rumit();
Query query = em.createQuery("SELECT e FROM Address e");
List<Address> list = (List<Address>) query.getResultList();
System.out.println(list.get(0).getStudent());
em.close();
emf.close();
Helper.checkData();
}
}
File: Student.java import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Student {
@Id
private int id;
private String name;
@OneToOne(cascade=CascadeType.ALL)
private Address address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String toString() {
return "\n\nID:" + id + "\nName:" + name + "\n\n";
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
Mark Entity RelationShip As One To One
<source lang="java">
File: Address.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.TableGenerator; @Entity public class Address {
@TableGenerator(name = "Address_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL", pkColumnValue = "Addr_Gen", initialValue = 10000, allocationSize = 100)
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "Address_Gen")
private int id;
private String street;
private String city;
private String state;
private String zip;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getStreet() {
return street;
}
public void setStreet(String address) {
this.street = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public String toString() {
return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
+ ", state: " + getState() + ", zip: " + getZip();
}
}
File: Professor.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.TableGenerator; @Entity public class Professor {
@TableGenerator(name = "Emp_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL")
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "Emp_Gen")
private int id;
private String name;
private long salary;
@OneToOne
private Address address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getSalary() {
return salary;
}
public void setSalary(long salary) {
this.salary = salary;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String toString() {
return "Professor id: " + getId() + " name: " + getName() + " salary: " + getSalary();
}
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em;
public ProfessorService(EntityManager em) {
this.em = em;
}
public Professor createProfessor(String name, long salary,
String street, String city, String state, String zip) {
Professor emp = new Professor();
emp.setName(name);
emp.setSalary(salary);
Address addr = new Address();
addr.setStreet(street);
addr.setCity(city);
addr.setState(state);
addr.setZip(zip);
emp.setAddress(addr);
em.persist(emp);
em.persist(addr);
return emp;
}
public void removeProfessor(int id) {
Professor emp = findProfessor(id);
if (emp != null) {
em.remove(emp);
}
}
public Professor raiseProfessorSalary(int id, long raise) {
Professor emp = em.find(Professor.class, id);
if (emp != null) {
emp.setSalary(emp.getSalary() + raise);
}
return emp;
}
public Professor findProfessor(int id) {
return em.find(Professor.class, id);
}
public Collection<Professor> findAllProfessors() {
Query query = em.createQuery("SELECT e FROM Professor e");
return (Collection<Professor>) query.getResultList();
}
}
File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil {
Statement st;
public JPAUtil() throws Exception{
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: Main.java import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main {
public static void main(String[] a) throws Exception {
JPAUtil util = new JPAUtil();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
EntityManager em = emf.createEntityManager();
ProfessorService service = new ProfessorService(em);
em.getTransaction().begin();
Professor emp = service.createProfessor("name", 100,
"street", "city", "state", "zip");
em.getTransaction().rumit();
System.out.println("Persisted " + emp);
util.checkData("select * from Professor");
util.checkData("select * from ADDRESS");
util.checkData("select * from ID_GEN");
em.close();
emf.close();
}
}
File: persistence.xml <persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
One To One Bidirectional
<source lang="java">
File: ParkingSpace.java
import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class ParkingSpace {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private int lot;
private String location;
@OneToOne(mappedBy="parkingSpace")
private Professor employee;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getLot() {
return lot;
}
public void setLot(int lot) {
this.lot = lot;
}
public String getLocation() {
return location;
}
public void setLocation(String deptName) {
this.location = deptName;
}
public String toString() {
return "ParkingSpace id: " + getId() + " lot: " + getLot() +
", location: " + getLocation();
}
}
File: Professor.java
import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; @Entity public class Professor {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private long salary;
@OneToOne
@JoinColumn(name="PSPACE_ID")
private ParkingSpace parkingSpace;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getSalary() {
return salary;
}
public void setSalary(long salary) {
this.salary = salary;
}
public ParkingSpace getParkingSpace() {
return parkingSpace;
}
public void setParkingSpace(ParkingSpace parkingSpace) {
this.parkingSpace = parkingSpace;
}
public String toString() {
return "Professor id: " + getId() + " name: " + getName() +
" with " + getParkingSpace();
}
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em;
public ProfessorService(EntityManager em) {
this.em = em;
}
public Professor createProfessor(String name, long salary) {
Professor emp = new Professor();
emp.setName(name);
emp.setSalary(salary);
em.persist(emp);
return emp;
}
public Professor setProfessorParkingSpace(int empId, int spaceId) {
Professor emp = em.find(Professor.class, empId);
ParkingSpace pSpace = em.find(ParkingSpace.class, spaceId);
emp.setParkingSpace(pSpace);
return emp;
}
public Collection<Professor> findAllProfessors() {
Query query = em.createQuery("SELECT e FROM Professor e");
return (Collection<Professor>) query.getResultList();
}
public ParkingSpace createParkingSpace(int lot, String location) {
ParkingSpace space = new ParkingSpace();
space.setLot(lot);
space.setLocation(location);
em.persist(space);
return space;
}
public Collection<ParkingSpace> findAllParkingSpaces() {
Query query = em.createQuery("SELECT p FROM ParkingSpace p");
return (Collection<ParkingSpace>) query.getResultList();
}
}
File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil {
Statement st;
public JPAUtil() throws Exception{
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main {
public static void main(String[] a) throws Exception {
JPAUtil util = new JPAUtil();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
EntityManager em = emf.createEntityManager();
ProfessorService service = new ProfessorService(em);
em.getTransaction().begin();
Professor emp = service.createProfessor("empName", 100);
ParkingSpace pSpace = service.createParkingSpace(1, "location");
Professor emp1 = service.setProfessorParkingSpace(emp.getId(), pSpace.getId());
Collection<Professor> emps = service.findAllProfessors();
if (emps.isEmpty()) {
System.out.println("No Professors found ");
} else {
System.out.println("Found Professors: ");
for (Professor emp2 : emps) {
System.out.println(emp2);
}
}
Collection<ParkingSpace> pSpaces = service.findAllParkingSpaces();
if (pSpaces.isEmpty()) {
System.out.println("No ParkingSpaces found ");
} else {
System.out.println("Found ParkingSpaces:");
for (ParkingSpace pSpace1 : pSpaces) {
System.out.println(pSpace1);
}
}
util.checkData("select * from Professor");
util.checkData("select * from ParkingSpace");
em.getTransaction().rumit();
em.close();
emf.close();
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
One To One MappedBy
<source lang="java">
File: ParkingSpace.java
import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.PrimaryKeyJoinColumn; import javax.persistence.Table; @Entity public class ParkingSpace {
@Id
private int id;
private int lot;
private String location;
@OneToOne
@PrimaryKeyJoinColumn
private Professor employee;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getLot() {
return lot;
}
public void setLot(int lot) {
this.lot = lot;
}
public String getLocation() {
return location;
}
public void setLocation(String deptName) {
this.location = deptName;
}
public Professor getProfessor() {
return employee;
}
public void setProfessor(Professor employee) {
this.employee = employee;
}
public String toString() {
return "ParkingSpace id: " + getId() + " lot: " + getLot() +
", location: " + getLocation();
}
}
File: Professor.java
import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Professor {
@Id
private int id;
private String name;
private long salary;
@OneToOne(mappedBy="employee")
private ParkingSpace parkingSpace;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getSalary() {
return salary;
}
public void setSalary(long salary) {
this.salary = salary;
}
public ParkingSpace getParkingSpace() {
return parkingSpace;
}
public void setParkingSpace(ParkingSpace parkingSpace) {
this.parkingSpace = parkingSpace;
}
public String toString() {
return "Professor id: " + getId() + " name: " + getName() +
" with " + getParkingSpace();
}
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em;
public ProfessorService(EntityManager em) {
this.em = em;
}
public Professor createProfessor(int id, String name, long salary) {
Professor emp = new Professor();
emp.setId(id);
emp.setName(name);
emp.setSalary(salary);
em.persist(emp);
return emp;
}
public Collection<Professor> findAllProfessors() {
Query query = em.createQuery("SELECT e FROM Professor e");
return (Collection<Professor>) query.getResultList();
}
public ParkingSpace createParkingSpace(Professor emp, int lot, String location) {
ParkingSpace space = new ParkingSpace();
space.setId(emp.getId());
space.setLot(lot);
space.setLocation(location);
emp.setParkingSpace(space);
space.setProfessor(emp);
em.persist(space);
return space;
}
public Collection<ParkingSpace> findAllParkingSpaces() {
Query query = em.createQuery("SELECT p FROM ParkingSpace p");
return (Collection<ParkingSpace>) query.getResultList();
}
}
File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil {
Statement st;
public JPAUtil() throws Exception{
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main {
public static void main(String[] a) throws Exception {
JPAUtil util = new JPAUtil();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
EntityManager em = emf.createEntityManager();
ProfessorService service = new ProfessorService(em);
em.getTransaction().begin();
Professor emp = service.createProfessor(1, "empName", 100L);
service.createParkingSpace(emp, 1, "location");
System.out.println("Created " + emp);
Collection<Professor> emps = service.findAllProfessors();
if (emps.isEmpty()) {
System.out.println("No Professors found ");
} else {
System.out.println("Found Professors:");
for (Professor emp1 : emps) {
System.out.println(emp1);
}
}
Collection<ParkingSpace> pSpaces = service.findAllParkingSpaces();
if (pSpaces.isEmpty()) {
System.out.println("No ParkingSpaces found ");
} else {
System.out.println("Found ParkingSpaces:");
for (ParkingSpace pSpace : pSpaces) {
System.out.println(pSpace);
}
}
util.checkData("select * from Professor");
util.checkData("select * from ParkingSpace");
em.getTransaction().rumit();
em.close();
emf.close();
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
One To One Mapping Based On Table Based ID
<source lang="java">
File: Address.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.TableGenerator; @Entity public class Address {
@TableGenerator(name = "Address_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL", pkColumnValue = "Addr_Gen", initialValue = 10000, allocationSize = 100)
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "Address_Gen")
private int id;
private String street;
private String city;
private String state;
private String zip;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getStreet() {
return street;
}
public void setStreet(String address) {
this.street = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public String toString() {
return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
+ ", state: " + getState() + ", zip: " + getZip();
}
}
File: Student.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.TableGenerator; @Entity public class Student {
@TableGenerator(name = "Emp_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL")
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "Emp_Gen")
private int id;
private String name;
@OneToOne
private Address address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String toString() {
return "\n\nID:" + id + "\nName:" + name + "\n\n";
}
}
File: Main.java import java.sql.Timestamp; import java.util.List; import java.util.UUID; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService");
static EntityManager em = emf.createEntityManager();
public static void main(String[] a) throws Exception {
em.getTransaction().begin();
Student student = new Student();
student.setName("Joe");
Address address = new Address();
em.persist(address);
student.setAddress(address);
em.persist(student);
em.flush();
em.getTransaction().rumit();
Query query = em.createQuery("SELECT e FROM Student e");
List<Student> list = (List<Student>) query.getResultList();
System.out.println(list);
em.close();
emf.close();
Helper.checkData();
}
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception {
Class.forName("org.hsqldb.jdbcDriver");
Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
Statement st = conn.createStatement();
ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" });
while (mrs.next()) {
String tableName = mrs.getString(3);
System.out.println("\n\n\n\nTable Name: "+ tableName);
ResultSet rs = st.executeQuery("select * from " + tableName);
ResultSetMetaData metadata = rs.getMetaData();
while (rs.next()) {
System.out.println(" Row:");
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", ");
System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": ");
Object value = rs.getObject(i + 1);
System.out.println(" Column Value: "+value+"\n");
}
}
}
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
One To One Mapping: Lazy load
<source lang="java">
File: ParkingSpace.java
import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity public class ParkingSpace {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private int lot;
private String location;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getLot() {
return lot;
}
public void setLot(int lot) {
this.lot = lot;
}
public String getLocation() {
return location;
}
public void setLocation(String deptName) {
this.location = deptName;
}
public String toString() {
return "ParkingSpace id: " + getId() + " lot: " + getLot() +
", location: " + getLocation();
}
}
File: Professor.java
import static javax.persistence.FetchType.LAZY; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Professor {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private long salary;
@OneToOne(fetch=LAZY)
private ParkingSpace parkingSpace;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getSalary() {
return salary;
}
public void setSalary(long salary) {
this.salary = salary;
}
public ParkingSpace getParkingSpace() {
return parkingSpace;
}
public void setParkingSpace(ParkingSpace parkingSpace) {
this.parkingSpace = parkingSpace;
}
public String toString() {
return "Professor id: " + getId() + " name: " + getName() +
" with " + getParkingSpace();
}
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em;
public ProfessorService(EntityManager em) {
this.em = em;
}
public Professor createProfessor(String name, long salary) {
Professor emp = new Professor();
emp.setName(name);
emp.setSalary(salary);
em.persist(emp);
return emp;
}
public Professor setProfessorParkingSpace(int empId, int spaceId) {
Professor emp = em.find(Professor.class, empId);
ParkingSpace pSpace = em.find(ParkingSpace.class, spaceId);
emp.setParkingSpace(pSpace);
return emp;
}
public Collection<Professor> findAllProfessors() {
Query query = em.createQuery("SELECT e FROM Professor e");
return (Collection<Professor>) query.getResultList();
}
public ParkingSpace createParkingSpace(int lot, String location) {
ParkingSpace space = new ParkingSpace();
space.setLot(lot);
space.setLocation(location);
em.persist(space);
return space;
}
public Collection<ParkingSpace> findAllParkingSpaces() {
Query query = em.createQuery("SELECT p FROM ParkingSpace p");
return (Collection<ParkingSpace>) query.getResultList();
}
}
File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil {
Statement st;
public JPAUtil() throws Exception{
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main {
public static void main(String[] a) throws Exception {
JPAUtil util = new JPAUtil();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
EntityManager em = emf.createEntityManager();
ProfessorService service = new ProfessorService(em);
em.getTransaction().begin();
Professor emp = service.createProfessor("empName", 100L);
ParkingSpace pSpace = service.createParkingSpace(1, "location");
emp = service.setProfessorParkingSpace(emp.getId(), pSpace.getId());
Collection<Professor> emps = service.findAllProfessors();
if (emps.isEmpty()) {
System.out.println("No Professors found ");
} else {
System.out.println("Found Professors:");
for (Professor emp1 : emps) {
System.out.println(emp1);
}
}
Collection<ParkingSpace> pSpaces = service.findAllParkingSpaces();
if (pSpaces.isEmpty()) {
System.out.println("No ParkingSpaces found ");
} else {
System.out.println("Found ParkingSpaces:");
for (ParkingSpace pSpace1 : pSpaces) {
System.out.println(pSpace1);
}
}
util.checkData("select * from Professor");
util.checkData("select * from ParkingSpace");
em.getTransaction().rumit();
em.close();
emf.close();
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
One To One Unidirectional Mapping
<source lang="java">
File: ParkingSpace.java
import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity public class ParkingSpace {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private int lot;
private String location;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getLot() {
return lot;
}
public void setLot(int lot) {
this.lot = lot;
}
public String getLocation() {
return location;
}
public void setLocation(String deptName) {
this.location = deptName;
}
public String toString() {
return "ParkingSpace id: " + getId() + " lot: " + getLot() +
", location: " + getLocation();
}
}
File: Professor.java
import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; @Entity public class Professor {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private long salary;
@OneToOne
@JoinColumn(name="PSPACE_ID")
private ParkingSpace parkingSpace;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getSalary() {
return salary;
}
public void setSalary(long salary) {
this.salary = salary;
}
public ParkingSpace getParkingSpace() {
return parkingSpace;
}
public void setParkingSpace(ParkingSpace parkingSpace) {
this.parkingSpace = parkingSpace;
}
public String toString() {
return "Professor id: " + getId() + " name: " + getName() +
" with " + getParkingSpace();
}
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em;
public ProfessorService(EntityManager em) {
this.em = em;
}
public Professor createProfessor(String name, long salary) {
Professor emp = new Professor();
emp.setName(name);
emp.setSalary(salary);
em.persist(emp);
return emp;
}
public Professor setProfessorParkingSpace(int empId, int spaceId) {
Professor emp = em.find(Professor.class, empId);
ParkingSpace pSpace = em.find(ParkingSpace.class, spaceId);
emp.setParkingSpace(pSpace);
return emp;
}
public Collection<Professor> findAllProfessors() {
Query query = em.createQuery("SELECT e FROM Professor e");
return (Collection<Professor>) query.getResultList();
}
public ParkingSpace createParkingSpace(int lot, String location) {
ParkingSpace space = new ParkingSpace();
space.setLot(lot);
space.setLocation(location);
em.persist(space);
return space;
}
public Collection<ParkingSpace> findAllParkingSpaces() {
Query query = em.createQuery("SELECT p FROM ParkingSpace p");
return (Collection<ParkingSpace>) query.getResultList();
}
}
File: JPAUtil.java import java.io.Reader; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class JPAUtil {
Statement st;
public JPAUtil() throws Exception{
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: Main.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class Main {
public static void main(String[] a) throws Exception {
JPAUtil util = new JPAUtil();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
EntityManager em = emf.createEntityManager();
ProfessorService service = new ProfessorService(em);
em.getTransaction().begin();
Professor emp = service.createProfessor("empName", 100);
ParkingSpace pSpace = service.createParkingSpace(1, "location");
Professor emp1 = service.setProfessorParkingSpace(emp.getId(), pSpace.getId());
Collection<Professor> emps = service.findAllProfessors();
if (emps.isEmpty()) {
System.out.println("No Professors found ");
} else {
System.out.println("Found Professors: ");
for (Professor emp2 : emps) {
System.out.println(emp2);
}
}
Collection<ParkingSpace> pSpaces = service.findAllParkingSpaces();
if (pSpaces.isEmpty()) {
System.out.println("No ParkingSpaces found ");
} else {
System.out.println("Found ParkingSpaces:");
for (ParkingSpace pSpace1 : pSpaces) {
System.out.println(pSpace1);
}
}
util.checkData("select * from Professor");
util.checkData("select * from ParkingSpace");
em.getTransaction().rumit();
em.close();
emf.close();
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
Retrieve One To One Mapped Entity
<source lang="java">
File: Address.java import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Address {
@Id
private int id;
private String street;
private String city;
private String state;
private String zip;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getStreet() {
return street;
}
public void setStreet(String address) {
this.street = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public String toString() {
return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
+ ", state: " + getState() + ", zip: " + getZip();
}
}
File: Student.java import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Student {
@Id
private int id;
private String name;
@OneToOne
private Address address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String toString() {
return "\n\nID:" + id + "\nName:" + name + "\n\n";
}
}
File: Main.java import java.sql.Timestamp; import java.util.List; import java.util.UUID; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService");
static EntityManager em = emf.createEntityManager();
public static void main(String[] a) throws Exception {
em.getTransaction().begin();
Student student = new Student();
student.setName("Joe");
Address address = new Address();
em.persist(address);
student.setAddress(address);
em.persist(student);
em.flush();
em.getTransaction().rumit();
Query query = em.createQuery("SELECT e FROM Student e");
List<Student> list = (List<Student>) query.getResultList();
System.out.println(list.get(0).getAddress());
em.close();
emf.close();
Helper.checkData();
}
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception {
Class.forName("org.hsqldb.jdbcDriver");
Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
Statement st = conn.createStatement();
ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" });
while (mrs.next()) {
String tableName = mrs.getString(3);
System.out.println("\n\n\n\nTable Name: "+ tableName);
ResultSet rs = st.executeQuery("select * from " + tableName);
ResultSetMetaData metadata = rs.getMetaData();
while (rs.next()) {
System.out.println(" Row:");
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", ");
System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": ");
Object value = rs.getObject(i + 1);
System.out.println(" Column Value: "+value+"\n");
}
}
}
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit>
</persistence>
</source>
