Hibernate example source code file (QuerySplitter.java)

This example Hibernate source code file (QuerySplitter.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, arraylist, coremessagelogger, hashset, mappingexception, note, querysplitter, querysplitter, sessionfactoryimplementor, sessionfactoryimplementor, set, string, string, stringbuffer, util

The Hibernate QuerySplitter.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * 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.hql.internal;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;

import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.MappingException;
import org.hibernate.hql.internal.classic.ParserHelper;
import org.hibernate.internal.util.StringHelper;
import org.jboss.logging.Logger;

/**
 * Provides query splitting methods, which were originally in QueryTranslator.
 * <br>
 * TODO: This will need to be refactored at some point.
 *
 * @author josh
 */
public final class QuerySplitter {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, QuerySplitter.class.getName());

	private static final Set BEFORE_CLASS_TOKENS = new HashSet();
	private static final Set NOT_AFTER_CLASS_TOKENS = new HashSet();

	static {
		BEFORE_CLASS_TOKENS.add( "from" );
		BEFORE_CLASS_TOKENS.add( "delete" );
		BEFORE_CLASS_TOKENS.add( "update" );
		//beforeClassTokens.add("new"); DEFINITELY DON'T HAVE THIS!!
		BEFORE_CLASS_TOKENS.add( "," );
		NOT_AFTER_CLASS_TOKENS.add( "in" );
		//notAfterClassTokens.add(",");
		NOT_AFTER_CLASS_TOKENS.add( "from" );
		NOT_AFTER_CLASS_TOKENS.add( ")" );
	}

	/**
	 * Private empty constructor.
	 * (or else checkstyle says: 'warning: Utility classes should not have a public or default constructor.')
	 */
	private QuerySplitter() {
	}

	/**
	 * Handle Hibernate "implicit" polymorphism, by translating the query string into
	 * several "concrete" queries against mapped classes.
	 */
	public static String[] concreteQueries(String query, SessionFactoryImplementor factory) throws MappingException {

		//scan the query string for class names appearing in the from clause and replace
		//with all persistent implementors of the class/interface, returning multiple
		//query strings (make sure we don't pick up a class in the select clause!)

		//TODO: this is one of the ugliest and most fragile pieces of code in Hibernate....

		String[] tokens = StringHelper.split( StringHelper.WHITESPACE + "(),", query, true );
		if ( tokens.length == 0 ) return new String[]{query}; // just especially for the trivial collection filter
		ArrayList placeholders = new ArrayList();
		ArrayList replacements = new ArrayList();
		StringBuffer templateQuery = new StringBuffer( 40 );
		int count = 0;
		String last = null;
		int nextIndex = 0;
		String next = null;
		boolean isSelectClause = false;

		templateQuery.append( tokens[0] );
		if ( "select".equals( tokens[0].toLowerCase() ) ) isSelectClause = true;

		for ( int i = 1; i < tokens.length; i++ ) {

			//update last non-whitespace token, if necessary
			if ( !ParserHelper.isWhitespace( tokens[i - 1] ) ) last = tokens[i - 1].toLowerCase();

			// select-range is terminated by declaration of "from"
			if ( "from".equals( tokens[i].toLowerCase() ) ) isSelectClause = false;

			String token = tokens[i];
			if ( !ParserHelper.isWhitespace( token ) || last == null ) {

				//scan for next non-whitespace token
				if ( nextIndex <= i ) {
					for ( nextIndex = i + 1; nextIndex < tokens.length; nextIndex++ ) {
						next = tokens[nextIndex].toLowerCase();
						if ( !ParserHelper.isWhitespace( next ) ) break;
					}
				}

				boolean process = !isSelectClause &&
						isJavaIdentifier( token ) &&
						isPossiblyClassName( last, next );

				if (process) {
					String importedClassName = getImportedClass( token, factory );
					if ( importedClassName != null ) {
						String[] implementors = factory.getImplementors( importedClassName );
						String placeholder = "$clazz" + count++ + "$";
						if ( implementors != null ) {
							placeholders.add( placeholder );
							replacements.add( implementors );
						}
						token = placeholder; // Note this!!
					}
				}

			}

			templateQuery.append( token );

		}
		String[] results = StringHelper.multiply( templateQuery.toString(), placeholders.iterator(), replacements.iterator() );
        if (results.length == 0) LOG.noPersistentClassesFound(query);
		return results;
	}

	private static boolean isPossiblyClassName(String last, String next) {
		return "class".equals( last ) || (
				BEFORE_CLASS_TOKENS.contains( last ) &&
				!NOT_AFTER_CLASS_TOKENS.contains( next )
			);
	}

	private static boolean isJavaIdentifier(String token) {
		return Character.isJavaIdentifierStart( token.charAt( 0 ) );
	}

	public static String getImportedClass(String name, SessionFactoryImplementor factory) {
		return factory.getImportedClassName( name );
	}
}