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