com.google.api.ads.common.lib.utils.NodeExtractor Maven / Gradle / Ivy

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Client library for Java for accessing ads APIs including DFP. If you want to use this library, you must also include another Maven artifact to specify which framework you would like to use it with. For example, to use DFP with Axis, you should include the "dfp-axis" artifact.

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// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed 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 com.google.api.ads.common.lib.utils;

import com.google.common.base.Preconditions;
import java.util.Iterator;
import javax.annotation.Nullable;
import javax.xml.xpath.XPathExpression;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Utility that extracts a {@link Node} from a parent node given a list of xpaths using DOM methods,
 * not {@link XPathExpression} objects.
 *
 * 
 * This utility exists because the {@code Node} objects produced by Axis and JAX-WS do not seem to
 * be compatible with {@link XPathExpression}.
 */
public class NodeExtractor {

  /**
   * Convenience method for getting the value of a node, handling the case where the node does not
   * exist.
   *
   * @return the value of the node at {@code xPath} if it exists, else {@code null}.
   */
  public String extractNodeValue(@Nullable Node parentNode, Iterable xPath) {
    Node node = extractNode(parentNode, xPath);
    if (node == null || node.getFirstChild() == null) {
      return null;
    }
    return node.getFirstChild().getNodeValue();
  }
  
  /**
   * Extracts the node specified by the xpath list.
   *
   * @param parentNode the node to extract the child node from.
   * @param xPath xpath elements for local names that make up the child node's xpath.
   * @return the matching {@link Node}, or {@code null} if no such child node exists.
   */
  public Node extractNode(@Nullable Node parentNode, Iterable xPath) {
    Preconditions.checkNotNull(xPath, "Null xpath list");
    Node node = parentNode;
    boolean wasMatch = false;
    Iterator xPathElementsIter = xPath.iterator();
    while (xPathElementsIter.hasNext() && node != null) {
      wasMatch = false;
      String localName = xPathElementsIter.next();
      NodeList childNodes = node.getChildNodes();
      for (int i = 0; i < childNodes.getLength(); i++) {
        Node childNode = childNodes.item(i);
        String childName = childNode.getLocalName();
        if (childName == null || childName.contains(":")) {
          childName = childNode.getNodeName();
        }
        if (localName.equals(childName)) {
          node = childNode;
          wasMatch = true;
          break;
        }
      }
    }
    return wasMatch ? node : null;
  }
}