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Relational Persistence for Java
There is a newer version: 3.6.0.Beta2
//$Id: Example.java 10061 2006-06-28 05:20:51Z [email protected] $
package org.hibernate.criterion;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.hibernate.Criteria;
import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.engine.TypedValue;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.type.AbstractComponentType;
import org.hibernate.type.Type;
import org.hibernate.util.StringHelper;

/**
 * Support for query by example.
 *  * List results = session.createCriteria(Parent.class)
 *     .add( Example.create(parent).ignoreCase() )
 *     .createCriteria("child")
 *         .add( Example.create( parent.getChild() ) )
 *     .list();
 * 
 * "Examples" may be mixed and matched with "Expressions" in the same Criteria.
 * @see org.hibernate.Criteria
 * @author Gavin King
 */

public class Example implements Criterion {

	private final Object entity;
	private final Set excludedProperties = new HashSet();
	private PropertySelector selector;
	private boolean isLikeEnabled;
	private Character escapeCharacter;
	private boolean isIgnoreCaseEnabled;
	private MatchMode matchMode;

	/**
	 * A strategy for choosing property values for inclusion in the query
	 * criteria
	 */

	public static interface PropertySelector extends Serializable {
		public boolean include(Object propertyValue, String propertyName, Type type);
	}

	private static final PropertySelector NOT_NULL = new NotNullPropertySelector();
	private static final PropertySelector ALL = new AllPropertySelector();
	private static final PropertySelector NOT_NULL_OR_ZERO = new NotNullOrZeroPropertySelector();

	static final class AllPropertySelector implements PropertySelector {
		public boolean include(Object object, String propertyName, Type type) {
			return true;
		}
		
		private Object readResolve() {
			return ALL;
		}
	}

	static final class NotNullPropertySelector implements PropertySelector {
		public boolean include(Object object, String propertyName, Type type) {
			return object!=null;
		}
		
		private Object readResolve() {
			return NOT_NULL;
		}
	}

	static final class NotNullOrZeroPropertySelector implements PropertySelector {
		public boolean include(Object object, String propertyName, Type type) {
			return object!=null && (
				!(object instanceof Number) || ( (Number) object ).longValue()!=0
			);
		}
		
		private Object readResolve() {
			return NOT_NULL_OR_ZERO;
		}
	}

	/**
	 * Set escape character for "like" clause
	 */
	public Example setEscapeCharacter(Character escapeCharacter) {
		this.escapeCharacter = escapeCharacter;
		return this;
	}

	/**
	 * Set the property selector
	 */
	public Example setPropertySelector(PropertySelector selector) {
		this.selector = selector;
		return this;
	}

	/**
	 * Exclude zero-valued properties
	 */
	public Example excludeZeroes() {
		setPropertySelector(NOT_NULL_OR_ZERO);
		return this;
	}

	/**
	 * Don't exclude null or zero-valued properties
	 */
	public Example excludeNone() {
		setPropertySelector(ALL);
		return this;
	}

	/**
	 * Use the "like" operator for all string-valued properties
	 */
	public Example enableLike(MatchMode matchMode) {
		isLikeEnabled = true;
		this.matchMode = matchMode;
		return this;
	}

	/**
	 * Use the "like" operator for all string-valued properties
	 */
	public Example enableLike() {
		return enableLike(MatchMode.EXACT);
	}

	/**
	 * Ignore case for all string-valued properties
	 */
	public Example ignoreCase() {
		isIgnoreCaseEnabled = true;
		return this;
	}

	/**
	 * Exclude a particular named property
	 */
	public Example excludeProperty(String name) {
		excludedProperties.add(name);
		return this;
	}

	/**
	 * Create a new instance, which includes all non-null properties
	 * by default
	 * @param entity
	 * @return a new instance of Example
	 */
	public static Example create(Object entity) {
		if (entity==null) throw new NullPointerException("null example");
		return new Example(entity, NOT_NULL);
	}

	protected Example(Object entity, PropertySelector selector) {
		this.entity = entity;
		this.selector = selector;
	}

	public String toString() {
		return "example (" + entity + ')';
	}

	private boolean isPropertyIncluded(Object value, String name, Type type) {
		return !excludedProperties.contains(name) &&
			!type.isAssociationType() &&
			selector.include(value, name, type);
	}

	public String toSqlString(Criteria criteria, CriteriaQuery criteriaQuery)
		throws HibernateException {

		StringBuffer buf = new StringBuffer().append('(');
		EntityPersister meta = criteriaQuery.getFactory().getEntityPersister( criteriaQuery.getEntityName(criteria) );
		String[] propertyNames = meta.getPropertyNames();
		Type[] propertyTypes = meta.getPropertyTypes();
		//TODO: get all properties, not just the fetched ones!
		Object[] propertyValues = meta.getPropertyValues( entity, getEntityMode(criteria, criteriaQuery) );
		for (int i=0; i