Hibernate example source code file (CompoundPredicate.java)

This example Hibernate source code file (CompoundPredicate.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

arraylist, booleanoperator, booleanoperator, compoundpredicate, compoundpredicate, criteriabuilderimpl, expression, expression, io, list, predicate, renderable, string, string, stringbuilder, util

The Hibernate CompoundPredicate.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
 * third-party contributors as indicated by either @author tags or express
 * copyright attribution statements applied by the authors.  All
 * third-party contributions are distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.ejb.criteria.predicate;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.persistence.criteria.Expression;
import javax.persistence.criteria.Predicate;
import org.hibernate.ejb.criteria.CriteriaBuilderImpl;
import org.hibernate.ejb.criteria.CriteriaQueryCompiler;
import org.hibernate.ejb.criteria.ParameterRegistry;
import org.hibernate.ejb.criteria.Renderable;

/**
 * A compound {@link Predicate predicate} is a grouping of other {@link Predicate predicates} in order to convert
 * either a conjunction (logical AND) or a disjunction (logical OR).
 *
 * @author Steve Ebersole
 */
public class CompoundPredicate
		extends AbstractPredicateImpl
		implements Serializable {
	private BooleanOperator operator;
	private final List<Expression expressions = new ArrayList>();

	/**
	 * Constructs an empty conjunction or disjunction.
	 *
	 * @param criteriaBuilder The query builder from which this originates.
	 * @param operator Indicates whether this predicate will function
	 * as a conjunction or disjunction.
	 */
	public CompoundPredicate(CriteriaBuilderImpl criteriaBuilder, BooleanOperator operator) {
		super( criteriaBuilder );
		this.operator = operator;
	}

	/**
	 * Constructs a conjunction or disjunction over the given expressions.
	 *
	 * @param criteriaBuilder The query builder from which this originates.
	 * @param operator Indicates whether this predicate will function
	 * as a conjunction or disjunction.
	 * @param expressions The expressions to be grouped.
	 */
	public CompoundPredicate(
			CriteriaBuilderImpl criteriaBuilder,
			BooleanOperator operator,
			Expression<Boolean>... expressions) {
		this( criteriaBuilder, operator );
		applyExpressions( expressions );
	}

	/**
	 * Constructs a conjunction or disjunction over the given expressions.
	 *
	 * @param criteriaBuilder The query builder from which this originates.
	 * @param operator Indicates whether this predicate will function
	 * as a conjunction or disjunction.
	 * @param expressions The expressions to be grouped.
	 */
	public CompoundPredicate(
			CriteriaBuilderImpl criteriaBuilder,
			BooleanOperator operator,
			List<Expression expressions) {
		this( criteriaBuilder, operator );
		applyExpressions( expressions );
	}

	private void applyExpressions(Expression<Boolean>... expressions) {
		applyExpressions( Arrays.asList( expressions ) );
	}

	private void applyExpressions(List<Expression expressions) {
		this.expressions.clear();
		this.expressions.addAll( expressions );
	}

	public BooleanOperator getOperator() {
		return operator;
	}

	public List<Expression getExpressions() {
		return expressions;
	}

	public void registerParameters(ParameterRegistry registry) {
		for ( Expression expression : getExpressions() ) {
			Helper.possibleParameter( expression, registry );
		}
	}

	public String render(CriteriaQueryCompiler.RenderingContext renderingContext) {
		if ( getExpressions().size() == 0 ) {
			boolean implicitTrue = getOperator() == BooleanOperator.AND;
			if ( isNegated() ) {
				implicitTrue = !implicitTrue;
			}
			return implicitTrue
					? "1=1" // true
					: "0=1"; // false
		}
		if ( getExpressions().size() == 1 ) {
			return ( (Renderable) getExpressions().get( 0 ) ).render( renderingContext );
		}
		final StringBuilder buffer = new StringBuilder();
		String sep = "";
		for ( Expression expression : getExpressions() ) {
			buffer.append( sep )
					.append( "( " )
					.append( ( (Renderable) expression ).render( renderingContext ) )
					.append( " )" );
			sep = operatorTextWithSeparator();
		}
		return buffer.toString();
	}

	private String operatorTextWithSeparator() {
		return getOperator() == BooleanOperator.AND
				? " and "
				: " or ";
	}

	public String renderProjection(CriteriaQueryCompiler.RenderingContext renderingContext) {
		return render( renderingContext );
	}

	/**
	 * Create negation of compound predicate by using logic rules:
	 * 1. not (x || y) is (not x && not y)
	 * 2. not (x && y) is (not x || not y)
	 */
	@Override
	public Predicate not() {
		toggleOperator();
		for ( Expression expr : this.getExpressions() ) {
			if ( Predicate.class.isInstance( expr ) ) {
				( (Predicate) expr ).not();
			}
		}
		return this;
	}

	private void toggleOperator() {
		if ( this.operator == BooleanOperator.AND ) {
			this.operator = BooleanOperator.OR;
		}
		else {
			this.operator = BooleanOperator.AND;
		}
	}
}