Hibernate - Component Mapping

public class Student {
    // It is always good to go with each attribute of MySQL
    // table
    private int studentId;
    private String firstName;
    private String lastName;
    private int grade;
    // Attributes that are available in 'Address' class. By
    // referring here, we can access them. As Component
    // Mapping is used, it is possible
    private Address address;
    // As address itself is set as an attribute in student
    // class,
    // all the address related arguments can be passed
    // easily via set method
    public Address getAddress() { return address; }

    public void setAddress(Address address)
    {
        this.address = address;
    }

    public int getStudentId() { return studentId; }

    public void setStudentId(int studentId)
    {
        this.studentId = studentId;
    }

    public String getFirstName() { return firstName; }

    public void setFirstName(String firstName)
    {
        this.firstName = firstName;
    }

    public String getLastName() { return lastName; }

    public void setLastName(String lastName)
    {
        this.lastName = lastName;
    }

    public int getGrade() { return grade; }

    public void setGrade(int grade) { this.grade = grade; }

    public Student(String firstName, String lastName,
                   int grade, Address address)
    {
        this.firstName = firstName;
        this.lastName = lastName;
        this.grade = grade;
        this.address = address;
    }

    public Student() {}
}

public class Address extends Student {
    private String streetName;
    private String cityName;
    private String stateName;
    private String zipCode;
    public Address() {}
    // We should have this constructor so that address
    // parameters
    // can be set easily and can be accessed in student
    // class
    public Address(String street, String city, String state,
                   String zipcode)
    {
        this.streetName = street;
        this.cityName = city;
        this.stateName = state;
        this.zipCode = zipcode;
    }
    public String getStreetName() { return streetName; }

    public void setStreetName(String streetName)
    {
        this.streetName = streetName;
    }

    public String getCityName() { return cityName; }

    public void setCityName(String cityName)
    {
        this.cityName = cityName;
    }

    public String getStateName() { return stateName; }

    public void setStateName(String stateName)
    {
        this.stateName = stateName;
    }

    public String getZipCode() { return zipCode; }

    public void setZipCode(String zipCode)
    {
        this.zipCode = zipCode;
    }
}

import com.gfg.componentmapping.pojo.Address;
import com.gfg.componentmapping.pojo.Student;
import java.util.Iterator;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class ComponentMappingPatternOfStoringData {
    private static SessionFactory factory;
    public static void main(String[] args)
    {

        try {
            factory = new Configuration()
                          .configure()
                          .buildSessionFactory();
        }
        catch (Throwable ex) {
            System.err.println(
                "Failed to create sessionFactory object."
                + ex);
            throw new ExceptionInInitializerError(ex);
        }

        ComponentMappingPatternOfStoringData
            componentMappingExample
            = new ComponentMappingPatternOfStoringData();

        // Address1 
        Address address1
            = componentMappingExample.addAddress(
                "ByepassRoad", "Chennai", "TN", "600028");

        // Add student records in the database
        Integer studentId
            = componentMappingExample.addStudent(
                "Ashwin", "Kumar", 10, address1);

        // Address2
        Address address2
            = componentMappingExample.addAddress(
                "Pattinapakkam", "Chennai", "TN", "600028");

        // Add another student record in the database
        Integer student2
            = componentMappingExample.addStudent(
                "Ruchitaa", "Agarwal", 8, address2);

        // List down all the students
        componentMappingExample.listStudents();

        // Update student's name as a sample
        componentMappingExample.updateStudent(studentId,
                                              "Nikilesh");

        // List down all the students. We can see the
        // updated value for the first student
        componentMappingExample.listStudents();
    }

    // Method to add an address record in the database
    public Address addAddress(String street, String city,
                              String state, String zipcode)
    {
        Session session = factory.openSession();
        Transaction tx = null;
        Integer addressID = null;
        Address address = null;

        try {
            tx = session.beginTransaction();
            address
                = new Address(street, city, state, zipcode);
            addressID = (Integer)session.save(address);
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
        return address;
    }

    // Method to add a student record in the database
    public Integer addStudent(String fname, String lname,
                              int salary, Address address)
    {
        Session session = factory.openSession();
        Transaction tx = null;
        Integer studentID = null;

        try {
            tx = session.beginTransaction();
            // By using Student constructor, we can see the
            // fields
            Student student = new Student(fname, lname,
                                          salary, address);
            studentID = (Integer)session.save(student);
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
        return employeeID;
    }

    // Method to list all the student detail
    public void listStudents()
    {
        Session session = factory.openSession();
        Transaction tx = null;

        try {
            tx = session.beginTransaction();
            // Take the data from Student table
            List students
                = session.createQuery("FROM Student")
                      .list();
            // Iterate the details and display them
            for (Iterator iterator = students.iterator();
                 iterator.hasNext();) {
                Student student = (Student)iterator.next();
                System.out.print("First Name: "
                                 + student.getFirstName());
                System.out.print("  Last Name: "
                                 + student.getLastName());
                System.out.println("  Grade: "
                                   + student.getGrade());
                Address add = student.getAddress();
                System.out.println("Address ");
                System.out.println("\tStreet: "
                                   + add.getStreetName());
                System.out.println("\tCity: "
                                   + add.getCityName());
                System.out.println("\tState: "
                                   + add.getStateName());
                System.out.println("\tZipcode: "
                                   + add.getZipCode());
            }
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
    }

    // Method to update name for a given student
    public void updateStudent(Integer studentId,
                              String firstName)
    {
        Session session = factory.openSession();
        Transaction tx = null;

        try {
            tx = session.beginTransaction();
            Student student = (Student)session.get(
                Student.class, studentId);
            student.setFirstName(firstName);
            session.update(student);
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
    }
}