JPA Tutorial - JPA ID GenerationType IDENTITY Example

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When using the auto generated value for id field we can select generation strategy. One common strategy we use is the IDENTITY.

Example

The following code is from Professor.java.

package com.java2s.common;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Professor {
  @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
  private int id;
  private String name;
  private long salary;

  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 long getSalary() {
    return salary;
  }

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

  public String toString() {
    return "Employee id: " + getId() + " name: " + getName() + " salary: "
        + getSalary();
  }
}

The following code is from App.java.

package com.java2s.common;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {

  public static void main(String[] args) {
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
        "applicationContext.xml");
    PersonDaoImpl dao = (PersonDaoImpl) context.getBean("personDao");

    dao.test();

    context.close();
    
    Helper.checkData();
  }
}

The following code is from PersonDaoImpl.java.

package com.java2s.common;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.springframework.transaction.annotation.Transactional;

@Transactional
public class PersonDaoImpl {
  public void test() {

    Professor emp = new Professor();

    emp.setName("name");
    emp.setSalary(12345);
    em.persist(emp);

  }

  @PersistenceContext
  private EntityManager em;
}

Here is the database table dump.

Table Name: PROFESSOR
 Row:
    Column Name: ID,
    Column Type: INTEGER:
    Column Value: 1

    Column Name: NAME,
    Column Type: VARCHAR:
    Column Value: name

    Column Name: SALARY,
    Column Type: BIGINT:
    Column Value: 12345

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