javabeanxpath.java

XML的解析、编译、查询等技术的JAVA源代码。

/*
 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/javabean/JavaBeanXPath.java,v 1.6 2006/06/03 20:36:00 elharo Exp $
 * $Revision: 1.6 $
 * $Date: 2006/06/03 20:36:00 $
 *
 * ====================================================================
 *
 * Copyright 2000-2002 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 *   * Neither the name of the Jaxen Project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ====================================================================
 * This software consists of voluntary contributions made by many 
 * individuals on behalf of the Jaxen Project and was originally 
 * created by bob mcwhirter <[e-mail]> and 
 * James Strachan <[e-mail]>.  For more information on the 
 * Jaxen Project, please see <http://www.jaxen.org/>.
 * 
 * $Id: JavaBeanXPath.java,v 1.6 2006/06/03 20:36:00 elharo Exp $
 */

package org.jaxen.javabean;

import org.jaxen.Context;
import org.jaxen.BaseXPath;
import org.jaxen.JaxenException;

import java.util.List;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

/** An XPath implementation for JavaBeans.
 *
 * <p>This is the main entry point for matching an XPath against a JavaBean
 * tree.  You create a compiled XPath object, then match it against
 * one or more context nodes using the {@link #selectNodes(Object)}
 * method, as in the following example:</p>
 *
 * <pre>
 * Node node = ...;
 * XPath path = new JavaBeanXPath("a/b/c");
 * List results = path.selectNodes(node);
 * </pre>
 *
 * @see BaseXPath
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter</a>
 *
 * @version $Revision: 1.6 $
 */
public class JavaBeanXPath extends BaseXPath
{
    /**
     * 
     */
    private static final long serialVersionUID = -1567521943360266313L;

    /** Construct given an XPath expression string.
     *
     *  @param xpathExpr The XPath expression.
     *
     *  @throws JaxenException if there is a syntax error while
     *          parsing the expression
     */
    public JavaBeanXPath(String xpathExpr) throws JaxenException
    {
        super( xpathExpr, DocumentNavigator.getInstance() );
    }

    protected Context getContext(Object node)
    {
        if ( node instanceof Context )
        {
            return (Context) node;
        }

        if ( node instanceof Element )
        {
            return super.getContext( node );
        }

        if ( node instanceof List )
        {
            List newList = new ArrayList();

            for ( Iterator listIter = ((List)node).iterator();
                  listIter.hasNext(); )
            {
                newList.add( new Element( null, "root", listIter.next() ) );
            }

            return super.getContext( newList );
        }

        return super.getContext( new Element( null, "root", node ) );
    }

    public Object evaluate(Object node)
        throws JaxenException
    {
        Object result = super.evaluate( node );

        if ( result instanceof Element )
        {
            return ((Element)result).getObject();
        }
        else if ( result instanceof Collection )
        {
            List newList = new ArrayList();

            for ( Iterator listIter = ((Collection)result).iterator();
                  listIter.hasNext(); )
            {
                Object member = listIter.next();

                if ( member instanceof Element )
                {
                    newList.add( ((Element)member).getObject() );
                }
                else
                {
                    newList.add( member );
                }
            }

            return newList;
        }

        return result;
    }
}