Java tutorial
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 java.util.ArrayList; import java.util.Collection; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; import javax.persistence.NamedNativeQuery; import javax.persistence.OneToMany; import javax.persistence.OneToOne; import javax.persistence.Table; @Entity @Table(name = "EMP") @NamedNativeQuery(name = "nativeSQL", query = "SELECT emp1.emp_id, emp1.name, emp1.manager_id, " + "emp1.dept_id, emp1.address_id " + "FROM EMP emp1, EMP emp2 " + "WHERE ((emp2.EMP_ID = ?) AND (emp2.EMP_ID = emp1.MANAGER_ID))", resultClass = Professor.class) public class Professor { @Id @Column(name = "EMP_ID") private int id; private String name; @OneToOne private Address address; @ManyToOne @JoinColumn(name = "DEPT_ID") private Department department; @ManyToOne @JoinColumn(name = "MANAGER_ID") private Professor manager; @OneToMany(mappedBy = "manager") private Collection<Professor> directs = new ArrayList<Professor>(); 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 Department getDepartment() { return department; } public void setDepartment(Department department) { this.department = department; } public Collection<Professor> getDirects() { return directs; } public void addDirect(Professor employee) { if (!getDirects().contains(employee)) { getDirects().add(employee); if (employee.getManager() != null) { employee.getManager().getDirects().remove(employee); } employee.setManager(this); } } public Professor getManager() { return manager; } public void setManager(Professor manager) { this.manager = manager; } public String toString() { return "Professor id: " + getId() + " name: " + getName() + " with MgrId: " + (getManager() == null ? null : getManager().getId()); } } File:Department.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class Department { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String deptName) { this.name = deptName; } public String toString() { return "Department id: " + getId() + ", name: " + getName(); } } File:ProfessorService.java import java.util.List; import javax.persistence.EntityManager; public class ProfessorService { protected EntityManager em; public ProfessorService(EntityManager em) { this.em = em; } public List findProfessorsReportingTo(int managerId) { return em.createNamedQuery("nativeSQL").setParameter(1, managerId) .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.findProfessorsReportingTo(1); util.checkData("select * from EMP"); em.getTransaction().commit(); em.close(); emf.close(); } } File:persistence.xml <persistence xmlns="http://java.sun.com/xml/ns/persistence"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/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>