JPA Tutorial - JPA ID SequenceGenerator Example

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We can use sequence to generate id for entities in database.

The following code shows how to use a sequence to do the id generation. It first uses the SequenceGenerator to create a sequence generator from a sequence, then it marks the name of the sequence generator in the @GeneratedValue annotation.

@SequenceGenerator(name="Emp_Gen", sequenceName="Emp_Seq")
@Id @GeneratedValue(generator="Emp_Gen")
private int id;

Example

The following code is from Professor.java.

package com.java2s.common;

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

@Entity
public class Professor {
  @SequenceGenerator(name="Emp_Gen", sequenceName="Emp_Seq")
  @Id @GeneratedValue(generator="Emp_Gen")
  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 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;
}

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 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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