Java/JPA/Join Columns
Содержание
Inversion Join Column
<source lang="java">
File: Professor.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; @Entity public class Professor {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int id; private String name; private long salary; @ManyToMany @JoinTable(name="EMP_PROJ", joinColumns=@JoinColumn(name="EMP_ID"), inverseJoinColumns=@JoinColumn(name="PROJ_ID")) private Collection<Project> projects; public Professor() { projects = new ArrayList<Project>(); } 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 void addProject(Project project) { if (!getProjects().contains(project)) { getProjects().add(project); } if (!project.getProfessors().contains(this)) { project.getProfessors().add(this); } } public Collection<Project> getProjects() { return projects; } public String toString() { return "Professor id: " + getId() + " name: " + getName() + " with " + getProjects().size() + " projects"; }
}
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 Project createProject(String name) { Project proj = new Project(); proj.setName(name); em.persist(proj); return proj; } public Collection<Project> findAllProjects() { Query query = em.createQuery("SELECT p FROM Project p"); return (Collection<Project>) query.getResultList(); } public Professor createProfessor(String name, long salary) { Professor emp = new Professor(); emp.setName(name); emp.setSalary(salary); em.persist(emp); return emp; } public Professor addProfessorProject(int empId, int projId) { Professor emp = em.find(Professor.class, empId); Project proj = em.find(Project.class, projId); proj.addProfessor(emp); return emp; } public Collection<Professor> findAllProfessors() { Query query = em.createQuery("SELECT e FROM Professor e"); return (Collection<Professor>) query.getResultList(); }
}
File: Project.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY) protected int id; protected String name; @ManyToMany(mappedBy="projects") private Collection<Professor> employees; public Project() { employees = new ArrayList<Professor>(); } public int getId() { return id; } public void setId(int projectNo) { this.id = projectNo; } public String getName() { return name; } public void setName(String projectName) { this.name = projectName; } public Collection<Professor> getProfessors() { return employees; } public void addProfessor(Professor employee) { if (!getProfessors().contains(employee)) { getProfessors().add(employee); } if (!employee.getProjects().contains(this)) { employee.getProjects().add(this); } } public String toString() { return "Project id: " + getId() + ", name: " + getName() + " with " + getProfessors().size() + " employees"; }
}
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); Project proj = service.createProject("projName");
emp = service.addProfessorProject(emp.getId(),proj.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<Project> projs = service.findAllProjects(); if (projs.isEmpty()) { System.out.println("No Projects found "); } else { System.out.println("Found Projects:"); for (Project proj1 : projs) { System.out.println(proj1); } } util.checkData("select * from Professor"); util.checkData("select * from Project"); em.getTransaction().rumit(); em.close(); emf.close(); }
}
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: 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>
Join Two Entities With Parameter
<source lang="java">
File: Department.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Department {
@Id private int id; private String name; @OneToMany(mappedBy="department") private Collection<Professor> employees; public Department() { employees = new ArrayList<Professor>(); } public int getId() { return id; } public String getName() { return name; } public Collection<Professor> getProfessors() { return employees; } public String toString() { return "Department no: " + getId() + ", name: " + getName(); }
}
File: Professor.java
import java.util.ArrayList; import java.util.Collection; import java.util.Date; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; import javax.persistence.ManyToOne; import javax.persistence.OneToMany; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity public class Professor {
@Id private int id; private String name; private long salary; @Temporal(TemporalType.DATE) private Date startDate; @ManyToOne private Professor manager; @OneToMany(mappedBy="manager") private Collection<Professor> directs; @ManyToOne private Department department; @ManyToMany private Collection<Project> projects; public Professor() { projects = new ArrayList<Project>(); directs = new ArrayList<Professor>(); } public int getId() { return id; } public String getName() { return name; } public long getSalary() { return salary; } public Date getStartDate() { return startDate; } public Department getDepartment() { return department; } public Collection<Professor> getDirects() { return directs; } public Professor getManager() { return manager; } public Collection<Project> getProjects() { return projects; } public String toString() { return "Professor " + getId() + ": name: " + getName() + ", salary: " + getSalary() + ", dept: " + ((getDepartment() == null) ? null : getDepartment().getName()); }
}
File: ProfessorService.java import java.util.Collection; import javax.persistence.EntityManager; import javax.persistence.NoResultException; public class ProfessorService {
protected EntityManager em; public ProfessorService(EntityManager em) { this.em = em; } public long queryEmpSalary(String deptName, String empName) { String query = "SELECT e.salary " + "FROM Professor e " + "WHERE e.department.name = "" + deptName + "" AND " + " e.name = "" + empName + """; try { return (Long) em.createQuery(query).getSingleResult(); } catch (NoResultException e) { return 0; } } public long queryEmpSalaryUsingParams(String deptName, String empName) { try { return (Long) em.createQuery( "SELECT e.salary " + "FROM Professor e " + "WHERE e.department.name = :deptName AND " + " e.name = :empName ").setParameter("deptName", deptName).setParameter("empName", empName).getSingleResult(); } catch (NoResultException e) { return 0; } }
}
File: Project.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project {
@Id protected int id; protected String name; @ManyToMany(mappedBy="projects") private Collection<Professor> employees; public Project() { employees = new ArrayList<Professor>(); } public int getId() { return id; } public String getName() { return name; } public Collection<Professor> getProfessors() { return employees; } public String toString() { return "Project id: " + getId() + ", name: " + getName(); }
}
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(); long l = service.queryEmpSalary("deptName", "empName"); long q = service.queryEmpSalaryUsingParams("deptName", "empName"); util.checkData("select * from Professor"); util.checkData("select * from Department"); 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>
Mark Joined Column As Nullable
<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: Professor.java
import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; @Entity public class Professor {
@Id private int id; @Column(nullable=false) private String name; private long salary; @ManyToOne @JoinColumn(nullable=false) 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(); }
}
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 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(); service.findAllProfessors(); util.checkData("select * from Professor"); 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>
Primary Key Column as Joined Column
<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>
Set Referenced Column Inverse Join Column
<source lang="java">
File: Professor.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.IdClass; import javax.persistence.JoinColumn; import javax.persistence.JoinColumns; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; import javax.persistence.ManyToOne; import javax.persistence.OneToMany; @Entity @IdClass(ProfessorId.class) public class Professor {
@Id private String country; @Id @Column(name="EMP_ID") private int id; private String name; private long salary; @ManyToOne @JoinColumns({ @JoinColumn(name="MGR_COUNTRY", referencedColumnName="COUNTRY"), @JoinColumn(name="MGR_ID", referencedColumnName="EMP_ID") }) private Professor manager; @OneToMany(mappedBy="manager") private Collection<Professor> directs; @ManyToMany @JoinTable( name="EMP_PROJECT", joinColumns={ @JoinColumn(name="EMP_COUNTRY", referencedColumnName="COUNTRY"), @JoinColumn(name="EMP_ID", referencedColumnName="EMP_ID")}, inverseJoinColumns=@JoinColumn(name="PROJECT_ID")) private Collection<Project> projects; public Professor() { directs = new ArrayList<Professor>(); projects = new ArrayList<Project>(); } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } 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 Collection<Professor> getDirects() { return directs; } public Professor getManager() { return manager; } public void setManager(Professor manager) { this.manager = manager; } public Collection<Project> getProjects() { return projects; } public String toString() { return "Professor id: " + getId() + " name: " + getName() + " country: " + getCountry(); }
}
File: ProfessorId.java import java.io.Serializable; import javax.persistence.Column; import javax.persistence.Embeddable; @Embeddable public class ProfessorId implements Serializable{
private String country; @Column(name = "EMP_ID") private int id; public ProfessorId() { } public ProfessorId(String country, int id) { this.country = country; this.id = id; } public String getCountry() { return country; } public int getId() { return id; } public boolean equals(Object o) { return ((o instanceof ProfessorId) && country.equals(((ProfessorId) o).getCountry()) && id == ((ProfessorId) o) .getId()); } public int hashCode() { return country.hashCode() + id; }
}
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 country, int id, String name, long salary) { Professor emp = new Professor(); emp.setCountry(country); emp.setId(id); emp.setName(name); emp.setSalary(salary); em.persist(emp); return emp; } public void createProject(String projName) { Project proj = new Project(); proj.setName(projName); em.persist(proj); } public void setProfessorManager(String country, int id, String mgrCountry, int mgrId) { Professor emp = findProfessor(country, id); Professor mgr = findProfessor(mgrCountry, mgrId); emp.setManager(mgr); mgr.getDirects().add(emp); } public void addProfessorProject(String country, int id, int projId) { Professor emp = findProfessor(country, id); Project proj = em.find(Project.class, projId); emp.getProjects().add(proj); proj.getProfessors().add(emp); } public Professor findProfessor(String country, int id) { return em.find(Professor.class, new ProfessorId(country, id)); } public Collection<Professor> findAllProfessors() { Query query = em.createQuery("SELECT e FROM Professor e"); return (Collection<Professor>) query.getResultList(); } public Collection<Project> findAllProjects() { Query query = em.createQuery("SELECT p FROM Project p"); return (Collection<Project>) query.getResultList(); }
}
File: Project.java import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project {
@Id protected int id; protected String name; @ManyToMany(mappedBy = "projects") protected Collection<Professor> employees = new ArrayList<Professor>(); public int getId() { return id; } public void setId(int projectNo) { this.id = projectNo; } public String getName() { return name; } public void setName(String projectName) { this.name = projectName; } public Collection<Professor> getProfessors() { return employees; } public void addProfessor(Professor employee) { if (!getProfessors().contains(employee)) { getProfessors().add(employee); } if (!employee.getProjects().contains(this)) { employee.getProjects().add(this); } } public String toString() { return getClass().getName().substring(getClass().getName().lastIndexOf(".") + 1) + " no: " + getId() + ", name: " + getName(); }
}
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(); service.createProfessor("country", 1, "name", 100); service.createProfessor("mgrcountry", 2, "mgrName", 100); service.createProject("proj"); service.addProfessorProject("empCountry2", 1, 1); service.setProfessorManager("Country", 1, "mgrCountry", 1);
System.out.println("Professors:"); for (Professor emp : service.findAllProfessors()) { System.out.println(emp + " " + emp.getProjects().size()); System.out.println(emp + " " + emp.getManager()); } System.out.println("Projects:"); for (Project p : service.findAllProjects()) { System.out.print(p + " " + p.getProfessors().size()); } util.checkData("select * from Professor"); 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>