childrencollector.java

jsr170接口的java实现。是个apache的开源项目。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jackrabbit.util;

import javax.jcr.Node;
import javax.jcr.Property;
import javax.jcr.RepositoryException;
import javax.jcr.util.TraversingItemVisitor;
import java.util.Collection;

/**
 * <code>ChildrenCollector</code> is a utility class
 * which can be used to 'collect' child elements of a
 * node. It implements the <code>ItemVisitor</code>
 * interface.
 */
public class ChildrenCollector extends TraversingItemVisitor.Default {

    private final Collection children;
    private final boolean collectNodes;
    private final boolean collectProperties;

    /**
     * Constructs a <code>ChildrenCollector</code>
     *
     * @param children          where the matching children should be added
     * @param collectNodes      true, if child nodes should be collected; otherwise false
     * @param collectProperties true, if child properties should be collected; otherwise false
     * @param maxLevel          number of hierarchy levels to traverse
     *                          (e.g. 1 for direct children only, 2 for children and their children, and so on)
     */
    public ChildrenCollector(Collection children, boolean collectNodes, boolean collectProperties, int maxLevel) {
        super(false, maxLevel);
        this.children = children;
        this.collectNodes = collectNodes;
        this.collectProperties = collectProperties;
    }

    /**
     * {@inheritDoc}
     */
    protected void entering(Node node, int level)
            throws RepositoryException {
        if (level > 0 && collectNodes) {
            children.add(node);
        }
    }

    /**
     * {@inheritDoc}
     */
    protected void entering(Property property, int level)
            throws RepositoryException {
        if (level > 0 && collectProperties) {
            children.add(property);
        }
    }
}