Hibernate Criteria Query Example

The Criteria interface allows to create and execute object-oriented queries. It is powerful alternative to the HQL but has own limitations. Criteria Query is used mostly in case of multi criteria search screens, where HQL is not very effective. 

The interface org.hibernate.Criteria is used to create the criterion for the search. The org.hibernate.Criteria interface represents a query against a persistent class. The Session is a factory for Criteria instances. Here is a simple example of Hibernate Criterial Query:

 

package roseindia.tutorial.hibernate; import org.hibernate.Session; import org.hibernate.*; import org.hibernate.cfg.*; import java.util.*; /**  * @author Deepak Kumar  *   * http://www.roseindia.net  Hibernate Criteria Query Example  *    */public class HibernateCriteriaQueryExample {   public static void main(String[] args) {   Session session = null;   try {   // This step will read  hibernate.cfg.xml and prepare hibernate for   // use   SessionFactory  sessionFactory = new Configuration().configure()   .buildSessionFactory();   session =  sessionFactory.openSession();   //Criteria Query Example   Criteria crit =  session.createCriteria(Insurance.class);   List insurances =  crit.list();   for(Iterator it =  insurances.iterator();it.hasNext();){   Insurance insurance =  (Insurance) it.next();   System.out.println(" ID: " + insurance.getLngInsuranceId());   System.out.println(" Name: " + insurance.getInsuranceName());      }   session.close();   } catch (Exception e) {   System.out.println(e.getMessage());   } finally {   }     } }

The above Criteria Query example selects all the records from the table and displays on the console. In the above code the following code creates a new Criteria instance, for the class Insurance:

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

The code:

List insurances = crit.list();

creates the sql query and execute against database to retrieve the data.

Criteria Query Examples

In the last lesson we learnt how to use Criteria Query to select all the records from Insurance table. In this lesson we will learn how to restrict the results returned from the database. Different method provided by Criteria interface can be used with the help of Restrictions to restrict the records fetched from database.

Criteria Interface provides the following methods:

Method	Description
add	The Add method adds a Criterion to constrain the results to be retrieved.
addOrder	Add an Order to the result set.
createAlias	Join an association, assigning an alias to the joined entity
createCriteria	This method is used to create a new Criteria, "rooted" at the associated entity.
setFetchSize	This method is used to set a fetch size for the underlying JDBC query.
setFirstResult	This method is used to set the first result to be retrieved.
setMaxResults	This method is used to set a limit upon the number of objects to be retrieved.
uniqueResult	This method is used to instruct the Hibernate to fetch and return the unique records from database.

Class Restriction provides built-in criterion via static factory methods. Important methods of the Restriction class are:

Method	Description
Restriction.allEq	This is used to apply an "equals" constraint to each property in the key set of a Map
Restriction.between	This is used to apply a "between" constraint to the named property
Restriction.eq	This is used to apply an "equal" constraint to the named property
Restriction.ge	This is used to apply a "greater than or equal" constraint to the named property
Restriction.gt	This is used to apply a "greater than" constraint to the named property
Restriction.idEq	This is used to apply an "equal" constraint to the identifier property
Restriction.ilike	This is case-insensitive "like", similar to Postgres ilike operator
Restriction.in	This is used to apply an "in" constraint to the named property
Restriction.isNotNull	This is used to apply an "is not null" constraint to the named property
Restriction.isNull	This is used to apply an "is null" constraint to the named property
Restriction.le	This is used to apply a "less than or equal" constraint to the named property
Restriction.like	This is used to apply a "like" constraint to the named property
Restriction.lt	This is used to apply a "less than" constraint to the named property
Restriction.ltProperty	This is used to apply a "less than" constraint to two properties
Restriction.ne	This is used to apply a "not equal" constraint to the named property
Restriction.neProperty	This is used to apply a "not equal" constraint to two properties
Restriction.not	This returns the negation of an expression
Restriction.or	This returns the disjuction of two expressions

Here is an example code that shows how to use Restrictions.like method and restrict the maximum rows returned by query by setting the Criteria.setMaxResults() value to 5.

package roseindia.tutorial.hibernate; import org.hibernate.Session; import org.hibernate.*; import org.hibernate.criterion.*; import org.hibernate.cfg.*; import java.util.*; /**  * @author Deepak Kumar  *   * http://www.roseindia.net  Hibernate Criteria Query Example  *    */public class HibernateCriteriaQueryExample2 {   public static void main(String[] args) {   Session session = null;   try {   // This step will read  hibernate.cfg.xml and prepare hibernate for   // use   SessionFactory sessionFactory  = new Configuration().configure()   .buildSessionFactory();   session =  sessionFactory.openSession();   //Criteria Query Example   Criteria crit =  session.createCriteria(Insurance.class);   crit.add(Restrictions.like(" insuranceName", "%a%")); //Like condition   crit.setMaxResults(5); // Restricts the max rows to 5   List insurances = crit.list();   for(Iterator it =  insurances.iterator();it.hasNext();){   Insurance insurance =  (Insurance) it.next();   System.out.println(" ID: " + insurance.getLngInsuranceId());   System.out.println(" Name: " + insurance.getInsuranceName());      }   session.close();   } catch (Exception e) {   System.out.println(e.getMessage());   } finally {   }     } }