Sequence Generator Name Init Value And Size : Generated ID « JPA « Java Tutorial

1. Java Tutorial
2. JPA
3. Generated ID

File: Customer.java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostRemove;
import javax.persistence.PostUpdate;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
import javax.persistence.SequenceGenerator;

@Entity
@SequenceGenerator(name = "SequenceIdGenerator", 
    sequenceName = "SEQ_ID_GEN", initialValue = 100, 
    allocationSize = 20)
public class Customer implements java.io.Serializable {
  @Id
  @GeneratedValue(generator = "SequenceIdGenerator")
  private int id;

  private String lastName;

  private String firstName;


  public int getId() {
    return id;
  }

  public void setId(int pk) {
    id = pk;
  }

  public String getLastName() {
    return lastName;
  }

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

  public String getFirstName() {
    return firstName;
  }

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

  @PrePersist
  public void prePersist() {
    System.out.println("@PrePersist");
  }

  @PostPersist
  public void postPersist() {
    System.out.println("@PostPersist");
  }

  @PostLoad
  public void postLoad() {
    System.out.println("@PostLoad");
  }

  @PreUpdate
  public void preUpdate() {
    System.out.println("@PreUpdate");
  }

  @PostUpdate
  public void postUpdate() {
    System.out.println("@PostUpdate");
  }

  @PreRemove
  public void preRemove() {
    System.out.println("@PreRemove");
  }

  @PostRemove
  public void postRemove() {
    System.out.println("@PostRemove");
  }

}

File: Helper.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

public class Helper {
  public static void checkData() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
    Statement st = conn.createStatement();

    ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" });
    while (mrs.next()) {
      String tableName = mrs.getString(3);
      System.out.println("\n\n\n\nTable Name: "+ tableName);

      ResultSet rs = st.executeQuery("select * from " + tableName);
      ResultSetMetaData metadata = rs.getMetaData();
      while (rs.next()) {
        System.out.println(" Row:");
        for (int i = 0; i < metadata.getColumnCount(); i++) {
          System.out.println("    Column Name: "+ metadata.getColumnLabel(i + 1)+ ",  ");
          System.out.println("    Column Type: "+ metadata.getColumnTypeName(i + 1)+ ":  ");
          Object value = rs.getObject(i + 1);
          System.out.println("    Column Value: "+value+"\n");
        }
      }
    }
  }
}

File: Main.java

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

public class Main {
  static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService");

  static EntityManager em = emf.createEntityManager();

  public static void main(String[] a) throws Exception {
    em.getTransaction().begin();


    Customer cus = new Customer();
    
    cus.setFirstName("asdf");
    
    em.persist(cus);

    em.getTransaction().commit();
    em.close();
    emf.close();

    Helper.checkData();
  }
}

File: persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

22.18.Generated ID
	22.18.1.	JPA Create Sequence Table For You
	22.18.2.	Use Sequence Generator
	22.18.3.	Sequence Generator Name Init Value And Size
	22.18.4.	ID Generation Type: TABLE
	22.18.5.	ID Generation Type: SEQUENCE
	22.18.6.	ID Generation Type: IDENTITY
	22.18.7.	ID Generation Type: AUTO
	22.18.8.	Generate ID From a Table
	22.18.9.	Generated Value Based On Sequence Generator
	22.18.10.	Create Your Own Table For Table Generator
	22.18.11.	Create Table From Table Generator