Hibernate criteria API

Till now we have seen how to manipulate tables using HQL (Hibernate Query language). Hibernate provides another way of manipulating objects using criteria API. It is a 3 step process.

Step 1: Create criteria object.

Ex:

Criteria crit = session.createCriteria(Employee.class);

Step 2: Apply filteration rules or logical conditions.

Ex:

crit.add(Restrictions.eq("id", 6));

Step 3: Get results of criteria query.

Ex:

List<Employee> empList = (List<Employee>)crit.list();

package myFirstHibernate;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedNativeQueries;
import javax.persistence.NamedNativeQuery;


@Entity(name="employee_details")
@NamedNativeQueries({
 @NamedNativeQuery(name="Employee.getById", query="select * from employee_details where id=?", resultClass=Employee.class),
 @NamedNativeQuery(name="Employee.getByFirstName", query="select * from employee_details where firstName=?", resultClass=Employee.class),
 @NamedNativeQuery(name="Employee.getByLastName", query="select * from employee_details where lastName=?", resultClass=Employee.class)
})
public class Employee {
 @Id @GeneratedValue
 private int id;
 private String firstName;
 private String lastName;
 
 public int getId() {
  return id;
 }
 
 public void setId(int id) {
  this.id = id;
 }
 
 public String getFirstName() {
  return firstName;
 }
 
 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }
 
 public String getLastName() {
  return lastName;
 }
 
 public void setLastName(String lastName) {
  this.lastName = lastName;
 }
 
}

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>

  <session-factory>
  
   <!--  Database Connection settings -->
    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="connection.url">jdbc:mysql://localhost/sample</property>
    <property name="connection.username">root</property>
    <property name="connection.password">tiger</property>
    
    <!-- Enable the logging of all the generated SQL statements to the console -->
    <property name="show_sql">true</property>
    
    <!-- Format the generated SQL statement to make it more readable, -->
    <property name="format_sql">false</property>
    
    <!-- Hibernate will put comments inside all generated SQL statements to hint what’s the generated SQL trying to do -->
    <property name="use_sql_comments">false</property>
    
    <!-- This property makes Hibernate generate the appropriate SQL for the chosen database. -->
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    
    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">create</property>
    
    <!-- mappings for annotated classes -->
    <mapping class="myFirstHibernate.Employee" />
    
  </session-factory>
  
</hibernate-configuration>

package myFirstHibernate;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;

public class TestEmployee {
 
 /* Step 1: Create session factory */
 private static SessionFactory getSessionFactory() {
  Configuration configuration = new Configuration().configure();
  StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().
  applySettings(configuration.getProperties());
  SessionFactory factory = configuration.buildSessionFactory(builder.build());
        return factory;
    }
 
 public static void main(String args[])throws Exception{
  
  Employee emp1 = new Employee();
  Employee emp2 = new Employee();
  Employee emp3 = new Employee();
  Employee emp4 = new Employee();
  Employee emp5 = new Employee();
  Employee emp6 = new Employee();
  Employee emp7 = new Employee();
  Employee emp8 = new Employee();
  
  emp1.setFirstName("Hari Krishna");
  emp1.setLastName("Gurram");
  
  emp2.setFirstName("Shreyas");
  emp2.setLastName("Desai");
  
  emp3.setFirstName("Piyush");
  emp3.setLastName("Rai");
  
  emp4.setFirstName("Rama Krishna");
  emp4.setLastName("Gurram");
  
  emp5.setFirstName("Sailaja");
  emp5.setLastName("Navakotla");
  
  emp6.setFirstName("Keerthi");
  emp6.setLastName("Parush");
  
  emp7.setFirstName("Gopi");
  emp7.setLastName("Battu");
  
  emp8.setFirstName("Jaideep");
  emp8.setLastName("Gera");
  
  SessionFactory sessionFactory = getSessionFactory();
  Session session = sessionFactory.openSession();
  session.beginTransaction();
  
  /* Saving objects to database */
  session.save(emp1);
  session.save(emp2);
  session.save(emp3);
  session.save(emp4);
  session.save(emp5);
  session.save(emp6);
  session.save(emp7);
  session.save(emp8);

  
  Criteria crit = session.createCriteria(Employee.class);
  crit.add(Restrictions.eq("id", 6));
  

  List<Employee> empList = (List<Employee>)crit.list();
  for(Employee emp : empList)
   System.out.println(emp.getId() + " " + emp.getFirstName() +" " + emp.getLastName());
  session.getTransaction().commit();
  session.close();
  
 }
}

Run TestEmployee class, you will get output like below.

Hibernate: drop table if exists employee_details
Hibernate: create table employee_details (id integer not null auto_increment, firstName varchar(255), lastName varchar(255), primary key (id))
Dec 23, 2014 4:36:04 PM org.hibernate.tool.hbm2ddl.SchemaExport execute
INFO: HHH000230: Schema export complete
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: insert into employee_details (firstName, lastName) values (?, ?)
Hibernate: select this_.id as id1_0_0_, this_.firstName as firstNam2_0_0_, this_.lastName as lastName3_0_0_ from employee_details this_ where this_.id=?
6 Keerthi Parush

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