[Tutorial] JPA 2.1 - Parte I

package model.dao;

import java.io.Serializable;

public interface GenericDao<T, PK extends Serializable> {
	T create(T t) throws Exception;
	T read(PK id) throws Exception;
	T update(T t) throws Exception;
	void delete(T t) throws Exception;
}

package model.dao;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

public class GenericDaoJpaImpl<T, PK extends Serializable> implements GenericDao<T, PK> {

	protected EntityManager em = Persistence.createEntityManagerFactory("JPA2-tuto").createEntityManager();
	protected Class<T> clazz;
	
	@SuppressWarnings("unchecked")
	public GenericDaoJpaImpl() {
		ParameterizedType genericSuperclass = (ParameterizedType) getClass()
	             .getGenericSuperclass();
	        this.clazz = (Class<T>) genericSuperclass
	             .getActualTypeArguments()[0];
	}
	
	@Override
	public T create(T t) throws Exception {
		EntityTransaction tx = em.getTransaction();
		tx.begin();
		em.persist(t);
		em.flush();
		tx.commit();
		return t;
	}

	@Override
	public T read(PK id) throws Exception {
		return em.find(clazz, id);
	}

	@Override
	public T update(T t) throws Exception {
		EntityTransaction tx = em.getTransaction();
		tx.begin();
		em.persist(t);
		em.flush();
		tx.commit();
		return t;
	}

	@Override
	public void delete(T t) throws Exception {
		EntityTransaction tx = em.getTransaction();
		tx.begin();
		em.remove(t);
		em.flush();
		tx.commit();
	}

}

protected EntityManager em = Persistence.createEntityManagerFactory("JPA2-tuto").createEntityManager();

Persistence.createEntityManagerFactory("JPA2-tuto")

createEntityManager()

EntityTransaction tx = em.getTransaction();

package model.dao;

import model.entities.Employee;

public class EmployeeDao extends GenericDaoJpaImpl<Employee, Short> {

	public EmployeeDao() {
		super();
	}
	
}

package model.entities;

import java.io.Serializable;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

@Entity
@Table(name="employees")
public class Employee implements Serializable {
	private static final long serialVersionUID = -4525913610632158800L;
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name="id_employee")
	@Id
	private Short id;
	@Column(name="names")
	private String names;
	@Column(name="surnames")
	private String surnames;
	@Temporal(TemporalType.DATE)
	@Column(name="birth_date")
	private Date birthDate;
	@Column(name="dni")
	private String dni;
	@Column(name="address")
	private String address;
	@Column(name="home_phone")
	private String homePhone;
	@Column(name="email")
	private String email;
	@Column(name="active")
	private Boolean active;
	
	public Employee() {}
	
	public Employee(Short id, String names, String surnames, Date birthDate,
			String dni, String address, String homePhone, String email,
			Boolean active) {
		super();
		this.id = id;
		this.names = names;
		this.surnames = surnames;
		this.birthDate = birthDate;
		this.dni = dni;
		this.address = address;
		this.homePhone = homePhone;
		this.email = email;
		this.active = active;
	}

	public Short getId() {
		return id;
	}

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

	public String getNames() {
		return names;
	}

	public void setNames(String names) {
		this.names = names;
	}

	public String getSurnames() {
		return surnames;
	}

	public void setSurnames(String surnames) {
		this.surnames = surnames;
	}

	public Date getBirthDate() {
		return birthDate;
	}

	public void setBirthDate(Date date) {
		this.birthDate = date;
	}

	public String getDni() {
		return dni;
	}

	public void setDni(String dni) {
		this.dni = dni;
	}

	public String getAddress() {
		return address;
	}

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

	public String getHomePhone() {
		return homePhone;
	}

	public void setHomePhone(String homePhone) {
		this.homePhone = homePhone;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public Boolean getActive() {
		return active;
	}

	public void setActive(Boolean active) {
		this.active = active;
	}
	
	
}

import java.util.logging.Logger;

import model.dao.EmployeeDao;
import model.entities.Employee;

public class Main {

	public static void main(String[] args) throws ParseException {
		try {
			EmployeeDao employeeDao = new EmployeeDao();
			Employee employee = new Employee();
			employee.setNames("Pepito");
			employee.setSurnames("Pérez");
			employee.setBirthDate(new SimpleDateFormat("yyyy-MM-dd").parse("1994-03-20"));
			employee.setDni("12345678");
			employee.setAddress("Av. que te importa #123");
			employee.setEmail("[email protected]");
			employee.setHomePhone("048389483");
			employee.setActive(true);
			employeeDao.create(employee);
		} catch (Exception e) {
			Logger.getLogger(Main.class.getName()).warning("Something was wrong: "+e.getMessage());
		} finally {
			System.exit(0);
		}
	}

}

package main;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.logging.Logger;

import model.dao.EmployeeDao;
import model.entities.Employee;

public class Main {

	public static void main(String[] args) throws ParseException {
		try {
			EmployeeDao employeeDao = new EmployeeDao();
			Employee employee = employeeDao.read(new Short("1"));
			// hacer lo que se desea con el empleado recuperado de la bbdd
		} catch (Exception e) {
			Logger.getLogger(Main.class.getName()).warning("Something was wrong: "+e.getMessage());
		} finally {
			System.exit(0);
		}
	}

}

 package main;

import java.text.ParseException;
import java.util.logging.Logger;

import model.dao.EmployeeDao;
import model.entities.Employee;

public class Main {

	public static void main(String[] args) throws ParseException {
		try {
			EmployeeDao employeeDao = new EmployeeDao();
			Employee employee = employeeDao.read(new Short("1"));
			employee.setNames("Bugs");
			employee.setSurnames("Bunny");
			employeeDao.update(employee);
		} catch (Exception e) {
			Logger.getLogger(Main.class.getName()).warning("Something was wrong: "+e.getMessage());
		} finally {
			System.exit(0);
		}
	}

}

 package main;

import java.text.ParseException;
import java.util.logging.Logger;
import model.dao.EmployeeDao;
import model.entities.Employee;

public class Main {

	public static void main(String[] args) throws ParseException {
		try {
			EmployeeDao employeeDao = new EmployeeDao();
			Employee employee = employeeDao.read(new Short("1"));
			employeeDao.delete(employee);
		} catch (Exception e) {
			Logger.getLogger(Main.class.getName()).warning("Something was wrong: "+e.getMessage());
		} finally {
			System.exit(0);
		}
	}

}