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.xml
and 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.