Powered by Blogger.

Friday, 12 December 2014

Sequence generator

By Shambhu Kumar  |  00:06 No comments

There are different ways to generate sequence
1) Automatic
2) Custom

1) Automatic
@GeneratedValue(strategy = GenerationType.SEQUENCE,generator= "countryid-gen")
@SequenceGenerator(name = "countryid-gen", sequenceName = "COUNTRY_SEQ",
              allocationSize = 1, initialValue = 0)
@Column(name = "COUNTRY_ID")

private int id;

2) Custom 
First need to create 
a) Custom Class, then 
b) implement that custom class.

a) Custom Class
package com.pristine.util;

import java.io.Serializable;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.lang3.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.IdentifierGenerator;

public class EmployeeCodeGenerator implements IdentifierGenerator {

    public Serializable generate(SessionImplementor session, Object object)
            throws HibernateException {

        String prefix = "E";
        Connection connection = session.connection();
        try {

            PreparedStatement ps = connection
                    .prepareStatement("SELECT nextval ('EMPLOYEE_SEQ') as nextval");

            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                int id = rs.getInt("nextval");
                String code = prefix + StringUtils.leftPad("" + id,3, '0');
                return code;

        } catch (SQLException e) {
            throw new HibernateException(
                    "Unable to generate Stock Code Sequence");
        return null;

b) Implementation of Custom Class
@GenericGenerator(name="seq_id", strategy="com.pristine.util.EmployeeCodeGenerator")
@Column(name = "ID", nullable = false)
private String id;

Author: Shambhu Kumar

Hello, I am Author, decode to know more: In commodo magna nisl, ac porta turpis blandit quis. Lorem ipsum dolor sit amet, consectetur adipiscing elit. In commodo magna nisl, ac porta turpis blandit quis. Lorem ipsum dolor sit amet.


Recent Articles

© 2014 Learning Java. WP themonic converted by Bloggertheme9. Published By Gooyaabi Templates