Hibernate Criteria API: Multi-Criteria Search Made Easy : Page 2

Introducing the Hibernate Query API

...
Criteria criteria 
            = session.createCriteria(Accommodation.class);
if (startDate != null) {
    criteria.add(Expression.ge("availabilityDate",
                               startDate);
}                
if (endDate != null) {
    criteria.add(Expression.le("availabilityDate",
                               endDate);
}                
// and so on

Listing 2. Using the Hibernate Criteria API for Multi-Criteria Queries

public List searchAccommodation(Date startDate,
                               Date endDate,
                               Country country,
                               AccommodationType type,
                               Integer capacity)
    Criteria criteria 
            = session.createCriteria(Accommodation.class);
    if (startDate != null) {
        criteria.add(Expression.ge("availabilityDate",
                                   startDate);
    }                
    if (endDate != null) {
        criteria.add(Expression.le("availabilityDate",
                               endDate);
    }                
    if (country != null) {
          criteria.add(Expression.eq("country",country);
    }                
    if (capacity != null) {
          criteria.add(Expression.ge("capacity",capacity);
    }                
    if (type != null) {
          criteria.add(Expression.eq("type",type);
    }                
    List results = criteria.list();
    //
    // Execute the query
    //
    return query.list();
}

Let's take a closer look at how you create and use the Criteria object. The principal class in the API is the Criteria class. You create a Criteria object using the createCriteria() method in the Hibernate session object:

Criteria criteria 
            = session.createCriteria(Accommodation.class);

Once created, you build the query by adding Criterion objects, obtained from the Expression class:

criteria.add(Expression.ge("availabilityDate",
                           startDate));
criteria.add(Expression.le("availabilityDate",
                           endDate));

You can also add 'order by' clauses:

criteria.addOrder( Order.asc("availabilityDate") )

You may use methods such as setFirstResult(), setMaxResults(), and setCacheable() to customize the query behavior in the same way as in the Query interface. So, to get the first 10 results, use the following commands:

criteria.setFirstResult(0)
criteria.setMaxResults(10)

Finally, to execute the query, invoke the list() method (or, if appropriate, the uniqueResult() method). Here is the full example:

List rooms = session.createCriteria(Accommodation.class)
              .add(Expression.ge("availabilityDate",
                                 startDate);
              .add(Expression.le("availabilityDate",
                                 endDate);
              .addOrder( Order.asc("availabilityDate") )
              .setFirstResult(0)
              .setMaxResults(10)
              .list();