Hibernate Select Query
In previous article we learnt to implement Hibernate 4 Insert Query example in Eclipse, In this article I will implement an example on loading the object from the database(Select Query) using Hibernate.
Project Structure
Entity class
package entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "STUDENT")
public class StudentEntity {
@Id
@Column(name = "ID")
private int id;
@Column(name = "NAME")
private String name;
@Column(name = "DEPARTMENT")
private String department;
@Column(name = "COLLEGE")
private String college;
// Create Getters and Setters
}
Note: I have explained about every annotations used in the above file in the article Generic Hibernate Application Requirements
Hibernate Configuration file
Create a new XML file and give this new configuration file the default name hibernate.cfg.xmland place it src directory of your project.
File: hibernate.cfg.xml
oracle.jdbc.driver.OracleDriver system admin jdbc:oracle:thin:@xxx.x.x.x:1521:XE org.hibernate.dialect.Oracle10gDialect true update
Hibernate Utility
package util;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import entity.StudentEntity;
public class HibernateUtil {
public static void main(String[] args) {
Configuration cf = new Configuration().configure("hibernate.cfg.xml");
StandardServiceRegistryBuilder srb = new StandardServiceRegistryBuilder();
srb.applySettings(cf.getProperties());
ServiceRegistry sr = srb.build();
SessionFactory sf = cf.buildSessionFactory(sr);
Session session = sf.openSession();
StudentEntity std = (StudentEntity) session.load(StudentEntity.class, new Integer(1));
// For loading Transaction object is not necessary
System.out.println("Loaded object Student name is: " + std.getName());
System.out.println("Object Loaded successfully.....!!");
session.close();
sf.close();
}
}
In the article Steps to be followed to use Hibernate in Java, I have explained the configuration/code used in above program in detail.
Data in Database
Run it – Eclipse Console
Note
In hibernate we have 2 methods to load the object from the database, they are get and load. To know the difference between get and load method read the article here.