Find entity by id

Sun May 09, 2010 12:06 pm

To find entity by id you can search for find function included EntityManager. Follow the example below :

Utility class :

Code:: package com.codemiles.jpa; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; /** * @author codemiles. */ public abstract class JPAService { private EntityManager entityManager; public Person findPersonById(String Id) { EntityManagerFactory factory = Persistence .createEntityManagerFactory("persistenceUnitName"); entityManager = factory.createEntityManager(); entityManager.getTransaction().begin(); Person person = entityManager.find(Person.class, Id); entityManager.getTransaction().commit(); entityManager.close(); factory.close(); if (person != null) { System.out.println("Person found for id = " +Id); } else { System.out.println("No person found for id = "+Id); } return person; } }

Person entity :

Code:: package com.codemiles.jpa; import java.util.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.EnumType; import javax.persistence.Enumerated; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.Table; @Entity @Table(name="PERSON") public class Person implements java.io.Serializable{ /** * */ private static final long serialVersionUID = 1L; @Id private String Id; private String name; private Date birthday; private String gender; @OneToOne(mappedBy="person") private Bed bed; public String getId() { return Id; } public void setId(String id) { Id = id; } @Column(name="NAME") public String getName() { return name; } public void setName(String name) { this.name = name; } @Column(name="BIRTHDAT") public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } @Column(name="GENDER") public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public void setBed(Bed bed) { this.bed = bed; } public Bed getBed() { return bed; } }