Month: July 2017

Employee.java

import javax.persistence.*;

@Entity
@Table(name = "EMPLOYEE")
public class Employee {
    @Id
    @GeneratedValue
    @Column(name = "id")
    private int id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "salary")
    private int salary;

    public Employee() {
    }

    public Employee(String fname, String lname, int salary) {
        this.firstName = fname;
        this.lastName = lname;
        this.salary = salary;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

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

    public String getLastName() {
        return lastName;
    }

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

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }
}

resources/META-INF/persistence.xml

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence

http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"

             version="2.1">

    <persistence-unit name="ir.mhdr.jpaDemo" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <class>Employee</class>

        <properties>
            <!-- Configuring JDBC properties -->
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost/testdb?useUnicode=yes&amp;characterEncoding=UTF-8&amp;useJDBCCompliantTimezoneShift=true&amp;useLegacyDatetimeCode=false&amp;serverTimezone=UTC" />
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="sampad622" />
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />

            <!-- Hibernate properties -->
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL57Dialect" />
            <property name="hibernate.hbm2ddl.auto" value="create" />

            <!-- Configuring Connection Pool -->
            <property name="hibernate.c3p0.min_size" value="5" />
            <property name="hibernate.c3p0.max_size" value="20" />
            <property name="hibernate.c3p0.timeout" value="500" />
            <property name="hibernate.c3p0.max_statements" value="50" />
            <property name="hibernate.c3p0.idle_test_period" value="2000" />
        </properties>
    </persistence-unit>
</persistence>

EmployeeBL.java

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.criteria.internal.CriteriaUpdateImpl;

import javax.persistence.*;
import javax.persistence.criteria.CriteriaUpdate;
import javax.transaction.Transaction;
import java.util.Iterator;
import java.util.List;

public class EmployeeBL {

    private EntityManagerFactory factory;

    public EmployeeBL() {
        factory = Persistence.createEntityManagerFactory("ir.mhdr.jpaDemo");
    }

    public void close() {
        factory.close();
    }

    /* Method to CREATE an employee in the database */
    public void addEmployee(String fname, String lname, int salary) {
        EntityManager entityManager = factory.createEntityManager();
        EntityTransaction tx = null;

        try {
            tx = entityManager.getTransaction();
            tx.begin();

            Employee employee = new Employee(fname, lname, salary);
            entityManager.persist(employee);

            tx.commit();
        } catch (Exception ex) {

            if (tx != null) tx.rollback();
            ex.printStackTrace();

        } finally {

            entityManager.close();
        }
    }


    /* Method to  READ all the employees */
    public void listEmployees() {
        EntityManager entityManager = factory.createEntityManager();
        EntityTransaction tx = null;

        try {
            tx = entityManager.getTransaction();
            tx.begin();

            List employees = entityManager.createQuery("from Employee").getResultList();
            for (Iterator iterator =
                 employees.iterator(); iterator.hasNext(); ) {
                Employee employee = (Employee) iterator.next();
                System.out.print("First Name: " + employee.getFirstName());
                System.out.print("  Last Name: " + employee.getLastName());
                System.out.println("  Salary: " + employee.getSalary());
            }

            tx.commit();
        } catch (Exception ex) {
            if (tx != null) tx.rollback();
            ex.printStackTrace();
        } finally {

            entityManager.close();

        }
    }


    /* Method to UPDATE salary for an employee */
    public void updateEmployee(Integer EmployeeID, int salary) {

        EntityManager entityManager = factory.createEntityManager();
        EntityTransaction tx = null;

        try {
            tx = entityManager.getTransaction();
            tx.begin();

            TypedQuery<Employee> query = entityManager.createQuery("select emp from Employee emp where id=:id", Employee.class);
            query.setParameter("id", EmployeeID);
            Employee employee = query.getSingleResult();

            employee.setSalary(salary);

            entityManager.persist(employee);

            tx.commit();
        } catch (Exception ex) {
            if (tx != null) tx.rollback();
            ex.printStackTrace();
        } finally {
            entityManager.close();
        }
    }


    /* Method to DELETE an employee from the records */
    public void deleteEmployee(Integer EmployeeID) {

        EntityManager entityManager = factory.createEntityManager();
        EntityTransaction tx = null;

        try {

            tx = entityManager.getTransaction();
            tx.begin();

            Employee employee = entityManager.find(Employee.class, EmployeeID);
            entityManager.remove(employee);

            tx.commit();

        } catch (Exception ex) {
            if (tx != null) tx.rollback();
            ex.printStackTrace();
        } finally {
            entityManager.close();
        }
    }
}

Main.java

public class Main {


    public static void main(String[] args)
    {
        EmployeeBL employeeBL=new EmployeeBL();
        employeeBL.addEmployee("Mahmood","Ramzani",1000);
        employeeBL.close();
    }
}

References
https://github.com/mhdr/HibernateSamples/tree/master/004_Persistent
http://docs.jboss.org/hibernate/orm/5.2/quickstart/html_single/#tutorial_jpa
https://dzone.com/articles/a-curious-java-language-feature-and-how-it-produce
https://www.sitepoint.com/5-reasons-to-use-jpa-hibernate/

EmployeeBL.java

public class EmployeeBL {
    private SessionFactory factory;

    public EmployeeBL() {
        Configuration configuration = new Configuration();
        this.factory = configuration.configure().buildSessionFactory();
    }

    public void insertRange(List<Employee> employeeList) {
        Session session = factory.openSession();
        session.setProperty("hibernate.jdbc.batch_size", 30);
        session.setProperty("hibernate.cache.use_second_level_cache", false);

        Transaction tx = session.beginTransaction();

        int i = 0;

        for (Employee employee : employeeList) {

            session.save(employee);
            i++;

            if (i % 30 == 0) { // same as the JDBC batch size
                //flush a batch of inserts and release memory:
                session.flush();
                session.clear();
            }
        }

        tx.commit();
        session.close();
    }
}

References
https://docs.jboss.org/hibernate/orm/3.3/reference/en-US/html/batch.html
https://github.com/mhdr/HibernateSamples/tree/master/003_BatchInsert