Java example source code file (DOMUtils.java)

This example Java source code file (DOMUtils.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

document, dom, element, excc14nparameterspec, iterator, marshalexception, node, nodelist, nodeset, string, suppresswarnings, util, xmlstructure, xpathfilter2parameterspec, xpathfilterparameterspec, xslttransformparameterspec

The DOMUtils.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/**
 * 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.
 */
/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * $Id: DOMUtils.java 1333415 2012-05-03 12:03:51Z coheigea $
 */
package org.jcp.xml.dsig.internal.dom;

import java.util.*;
import java.security.spec.AlgorithmParameterSpec;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.crypto.*;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dsig.spec.*;

/**
 * Useful static DOM utility methods.
 *
 * @author Sean Mullan
 */
public class DOMUtils {

    // class cannot be instantiated
    private DOMUtils() {}

    /**
     * Returns the owner document of the specified node.
     *
     * @param node the node
     * @return the owner document
     */
    public static Document getOwnerDocument(Node node) {
        if (node.getNodeType() == Node.DOCUMENT_NODE) {
            return (Document)node;
        } else {
            return node.getOwnerDocument();
        }
    }

    /**
     * Creates an element in the specified namespace, with the specified tag
     * and namespace prefix.
     *
     * @param doc the owner document
     * @param tag the tag
     * @param nsURI the namespace URI
     * @param prefix the namespace prefix
     * @return the newly created element
     */
    public static Element createElement(Document doc, String tag,
                                        String nsURI, String prefix)
    {
        String qName = (prefix == null || prefix.length() == 0)
                       ? tag : prefix + ":" + tag;
        return doc.createElementNS(nsURI, qName);
    }

    /**
     * Sets an element's attribute (using DOM level 2) with the
     * specified value and namespace prefix.
     *
     * @param elem the element to set the attribute on
     * @param name the name of the attribute
     * @param value the attribute value. If null, no attribute is set.
     */
    public static void setAttribute(Element elem, String name, String value) {
        if (value == null) {
            return;
        }
        elem.setAttributeNS(null, name, value);
    }

    /**
     * Sets an element's attribute (using DOM level 2) with the
     * specified value and namespace prefix AND registers the ID value with
     * the specified element. This is for resolving same-document
     * ID references.
     *
     * @param elem the element to set the attribute on
     * @param name the name of the attribute
     * @param value the attribute value. If null, no attribute is set.
     */
    public static void setAttributeID(Element elem, String name, String value) {
        if (value == null) {
            return;
        }
        elem.setAttributeNS(null, name, value);
        elem.setIdAttributeNS(null, name, true);
    }

    /**
     * Returns the first child element of the specified node, or null if there
     * is no such element.
     *
     * @param node the node
     * @return the first child element of the specified node, or null if there
     *    is no such element
     * @throws NullPointerException if <code>node == null
     */
    public static Element getFirstChildElement(Node node) {
        Node child = node.getFirstChild();
        while (child != null && child.getNodeType() != Node.ELEMENT_NODE) {
            child = child.getNextSibling();
        }
        return (Element)child;
    }

    /**
     * Returns the first child element of the specified node and checks that
     * the local name is equal to {@code localName}.
     *
     * @param node the node
     * @return the first child element of the specified node
     * @throws NullPointerException if {@code node == null}
     * @throws MarshalException if no such element or the local name is not
     *    equal to {@code localName}
     */
    public static Element getFirstChildElement(Node node, String localName)
        throws MarshalException
    {
        return verifyElement(getFirstChildElement(node), localName);
    }

    private static Element verifyElement(Element elem, String localName)
        throws MarshalException
    {
        if (elem == null) {
            throw new MarshalException("Missing " + localName + " element");
        }
        String name = elem.getLocalName();
        if (!name.equals(localName)) {
            throw new MarshalException("Invalid element name: " +
                                       name + ", expected " + localName);
        }
        return elem;
    }

    /**
     * Returns the last child element of the specified node, or null if there
     * is no such element.
     *
     * @param node the node
     * @return the last child element of the specified node, or null if there
     *    is no such element
     * @throws NullPointerException if <code>node == null
     */
    public static Element getLastChildElement(Node node) {
        Node child = node.getLastChild();
        while (child != null && child.getNodeType() != Node.ELEMENT_NODE) {
            child = child.getPreviousSibling();
        }
        return (Element)child;
    }

    /**
     * Returns the next sibling element of the specified node, or null if there
     * is no such element.
     *
     * @param node the node
     * @return the next sibling element of the specified node, or null if there
     *    is no such element
     * @throws NullPointerException if <code>node == null
     */
    public static Element getNextSiblingElement(Node node) {
        Node sibling = node.getNextSibling();
        while (sibling != null && sibling.getNodeType() != Node.ELEMENT_NODE) {
            sibling = sibling.getNextSibling();
        }
        return (Element)sibling;
    }

    /**
     * Returns the next sibling element of the specified node and checks that
     * the local name is equal to {@code localName}.
     *
     * @param node the node
     * @return the next sibling element of the specified node
     * @throws NullPointerException if {@code node == null}
     * @throws MarshalException if no such element or the local name is not
     *    equal to {@code localName}
     */
    public static Element getNextSiblingElement(Node node, String localName)
        throws MarshalException
    {
        return verifyElement(getNextSiblingElement(node), localName);
    }

    /**
     * Returns the attribute value for the attribute with the specified name.
     * Returns null if there is no such attribute, or
     * the empty string if the attribute value is empty.
     *
     * <p>This works around a limitation of the DOM
     * <code>Element.getAttributeNode method, which does not distinguish
     * between an unspecified attribute and an attribute with a value of
     * "" (it returns "" for both cases).
     *
     * @param elem the element containing the attribute
     * @param name the name of the attribute
     * @return the attribute value (may be null if unspecified)
     */
    public static String getAttributeValue(Element elem, String name) {
        Attr attr = elem.getAttributeNodeNS(null, name);
        return (attr == null) ? null : attr.getValue();
    }

    /**
     * Returns a Set of <code>Nodes, backed by the specified
     * <code>NodeList.
     *
     * @param nl the NodeList
     * @return a Set of Nodes
     */
    public static Set<Node> nodeSet(NodeList nl) {
        return new NodeSet(nl);
    }

    static class NodeSet extends AbstractSet<Node> {
        private NodeList nl;
        public NodeSet(NodeList nl) {
            this.nl = nl;
        }

        public int size() { return nl.getLength(); }
        public Iterator<Node> iterator() {
            return new Iterator<Node>() {
                int index = 0;

                public void remove() {
                    throw new UnsupportedOperationException();
                }
                public Node next() {
                    if (!hasNext()) {
                        throw new NoSuchElementException();
                    }
                    return nl.item(index++);
                }
                public boolean hasNext() {
                    return index < nl.getLength() ? true : false;
                }
            };
        }
    }

    /**
     * Returns the prefix associated with the specified namespace URI
     *
     * @param context contains the namespace map
     * @param nsURI the namespace URI
     * @return the prefix associated with the specified namespace URI, or
     *    null if not set
     */
    public static String getNSPrefix(XMLCryptoContext context, String nsURI) {
        if (context != null) {
            return context.getNamespacePrefix
                (nsURI, context.getDefaultNamespacePrefix());
        } else {
            return null;
        }
    }

    /**
     * Returns the prefix associated with the XML Signature namespace URI
     *
     * @param context contains the namespace map
     * @return the prefix associated with the specified namespace URI, or
     *    null if not set
     */
    public static String getSignaturePrefix(XMLCryptoContext context) {
        return getNSPrefix(context, XMLSignature.XMLNS);
    }

    /**
     * Removes all children nodes from the specified node.
     *
     * @param node the parent node whose children are to be removed
     */
    public static void removeAllChildren(Node node) {
        NodeList children = node.getChildNodes();
        for (int i = 0, length = children.getLength(); i < length; i++) {
            node.removeChild(children.item(i));
        }
    }

    /**
     * Compares 2 nodes for equality. Implementation is not complete.
     */
    public static boolean nodesEqual(Node thisNode, Node otherNode) {
        if (thisNode == otherNode) {
            return true;
        }
        if (thisNode.getNodeType() != otherNode.getNodeType()) {
            return false;
        }
        // FIXME - test content, etc
        return true;
    }

    /**
     * Checks if child element has same owner document before
     * appending to the parent, and imports it to the parent's document
     * if necessary.
     */
    public static void appendChild(Node parent, Node child) {
        Document ownerDoc = getOwnerDocument(parent);
        if (child.getOwnerDocument() != ownerDoc) {
            parent.appendChild(ownerDoc.importNode(child, true));
        } else {
            parent.appendChild(child);
        }
    }

    public static boolean paramsEqual(AlgorithmParameterSpec spec1,
        AlgorithmParameterSpec spec2) {
        if (spec1 == spec2) {
            return true;
        }
        if (spec1 instanceof XPathFilter2ParameterSpec &&
            spec2 instanceof XPathFilter2ParameterSpec) {
            return paramsEqual((XPathFilter2ParameterSpec)spec1,
                               (XPathFilter2ParameterSpec)spec2);
        }
        if (spec1 instanceof ExcC14NParameterSpec &&
            spec2 instanceof ExcC14NParameterSpec) {
            return paramsEqual((ExcC14NParameterSpec) spec1,
                               (ExcC14NParameterSpec)spec2);
        }
        if (spec1 instanceof XPathFilterParameterSpec &&
            spec2 instanceof XPathFilterParameterSpec) {
            return paramsEqual((XPathFilterParameterSpec)spec1,
                               (XPathFilterParameterSpec)spec2);
        }
        if (spec1 instanceof XSLTTransformParameterSpec &&
            spec2 instanceof XSLTTransformParameterSpec) {
            return paramsEqual((XSLTTransformParameterSpec)spec1,
                               (XSLTTransformParameterSpec)spec2);
        }
        return false;
    }

    private static boolean paramsEqual(XPathFilter2ParameterSpec spec1,
                                       XPathFilter2ParameterSpec spec2)
    {
        @SuppressWarnings("unchecked")
        List<XPathType> types = spec1.getXPathList();
        @SuppressWarnings("unchecked")
        List<XPathType> otypes = spec2.getXPathList();
        int size = types.size();
        if (size != otypes.size()) {
            return false;
        }
        for (int i = 0; i < size; i++) {
            XPathType type = types.get(i);
            XPathType otype = otypes.get(i);
            if (!type.getExpression().equals(otype.getExpression()) ||
                !type.getNamespaceMap().equals(otype.getNamespaceMap()) ||
                type.getFilter() != otype.getFilter()) {
                return false;
            }
        }
        return true;
    }

    private static boolean paramsEqual(ExcC14NParameterSpec spec1,
                                       ExcC14NParameterSpec spec2)
    {
        return spec1.getPrefixList().equals(spec2.getPrefixList());
    }

    private static boolean paramsEqual(XPathFilterParameterSpec spec1,
                                       XPathFilterParameterSpec spec2)
    {
        return (spec1.getXPath().equals(spec2.getXPath()) &&
                spec1.getNamespaceMap().equals(spec2.getNamespaceMap()));
    }

    private static boolean paramsEqual(XSLTTransformParameterSpec spec1,
                                       XSLTTransformParameterSpec spec2)
    {

        XMLStructure ostylesheet = spec2.getStylesheet();
        if (!(ostylesheet instanceof javax.xml.crypto.dom.DOMStructure)) {
            return false;
        }
        Node ostylesheetElem =
            ((javax.xml.crypto.dom.DOMStructure) ostylesheet).getNode();
        XMLStructure stylesheet = spec1.getStylesheet();
        Node stylesheetElem =
            ((javax.xml.crypto.dom.DOMStructure) stylesheet).getNode();
        return nodesEqual(stylesheetElem, ostylesheetElem);
    }
}