domelementwriter.java

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/*
 *  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.tools.ant.util;

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

/**
 * Writes a DOM tree to a given Writer.
 * warning: this utility currently does not declare XML Namespaces.
 * <p>Utility class used by {@link org.apache.tools.ant.XmlLogger
 * XmlLogger} and
 * org.apache.tools.ant.taskdefs.optional.junit.XMLJUnitResultFormatter
 * XMLJUnitResultFormatter}.</p>
 *
 */
public class DOMElementWriter {

    private static final int HEX = 16;

    /** prefix for generated prefixes */
    private static final String NS = "ns";

    /** xml declaration is on by default */
    private boolean xmlDeclaration = true;

    /**
     * XML Namespaces are ignored by default.
     */
    private XmlNamespacePolicy namespacePolicy = XmlNamespacePolicy.IGNORE;

    /**
     * Map (URI to prefix) of known namespaces.
     */
    private HashMap nsPrefixMap = new HashMap();

    /**
     * Number of generated prefix to use next.
     */
    private int nextPrefix = 0;

    /**
     * Map (Element to URI) of namespaces defined on a given element.
     */
    private HashMap nsURIByElement = new HashMap();

    /**
     * Whether namespaces should be ignored for elements and attributes.
     *
     * @since Ant 1.7
     */
    public static class XmlNamespacePolicy {
        private boolean qualifyElements;
        private boolean qualifyAttributes;

        /**
         * Ignores namespaces for elements and attributes, the default.
         */
        public static final XmlNamespacePolicy IGNORE =
            new XmlNamespacePolicy(false, false);

        /**
         * Ignores namespaces for attributes.
         */
        public static final XmlNamespacePolicy ONLY_QUALIFY_ELEMENTS =
            new XmlNamespacePolicy(true, false);

        /**
         * Qualifies namespaces for elements and attributes.
         */
        public static final XmlNamespacePolicy QUALIFY_ALL =
            new XmlNamespacePolicy(true, true);

        /**
         * @param qualifyElements whether to qualify elements
         * @param qualifyAttributes whether to qualify elements
         */
        public XmlNamespacePolicy(boolean qualifyElements,
                                  boolean qualifyAttributes) {
            this.qualifyElements = qualifyElements;
            this.qualifyAttributes = qualifyAttributes;
        }
    }

    /**
     * Create an element writer.
     * The ?xml? declaration will be included, namespaces ignored.
     */
    public DOMElementWriter() {
    }

    /**
     * Create an element writer
     * XML namespaces will be ignored.
     * @param xmlDeclaration flag to indicate whether the ?xml? declaration
     * should be included.
     * @since Ant1.7
     */
    public DOMElementWriter(boolean xmlDeclaration) {
        this(xmlDeclaration, XmlNamespacePolicy.IGNORE);
    }

    /**
     * Create an element writer
     * XML namespaces will be ignored.
     * @param xmlDeclaration flag to indicate whether the ?xml? declaration
     * should be included.
     * @param namespacePolicy the policy to use.
     * @since Ant1.7
     */
    public DOMElementWriter(boolean xmlDeclaration,
                            XmlNamespacePolicy namespacePolicy) {
        this.xmlDeclaration = xmlDeclaration;
        this.namespacePolicy = namespacePolicy;
    }

    private static String lSep = System.getProperty("line.separator");

    // CheckStyle:VisibilityModifier OFF - bc
    /**
     * Don't try to be too smart but at least recognize the predefined
     * entities.
     */
    protected String[] knownEntities = {"gt", "amp", "lt", "apos", "quot"};
    // CheckStyle:VisibilityModifier ON


    /**
     * Writes a DOM tree to a stream in UTF8 encoding. Note that
     * it prepends the &lt;?xml version='1.0' encoding='UTF-8'?&gt; if
     * the xmlDeclaration field is true.
     * The indent number is set to 0 and a 2-space indent.
     * @param root the root element of the DOM tree.
     * @param out the outputstream to write to.
     * @throws IOException if an error happens while writing to the stream.
     */
    public void write(Element root, OutputStream out) throws IOException {
        Writer wri = new OutputStreamWriter(out, "UTF8");
        writeXMLDeclaration(wri);
        write(root, wri, 0, "  ");
        wri.flush();
    }

    /**
     * Writes the XML declaration if xmlDeclaration is true.
     * @param wri the writer to write to.
     * @throws IOException if there is an error.
     * @since Ant 1.7.0
     */
    public void writeXMLDeclaration(Writer wri) throws IOException {
        if (xmlDeclaration) {
            wri.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
        }
    }

    /**
     * Writes a DOM tree to a stream.
     *
     * @param element the Root DOM element of the tree
     * @param out where to send the output
     * @param indent number of
     * @param indentWith string that should be used to indent the
     * corresponding tag.
     * @throws IOException if an error happens while writing to the stream.
     */
    public void write(Element element, Writer out, int indent,
                      String indentWith)
        throws IOException {

        // Write child elements and text
        NodeList children = element.getChildNodes();
        boolean hasChildren = (children.getLength() > 0);
        boolean hasChildElements = false;
        openElement(element, out, indent, indentWith, hasChildren);

        if (hasChildren) {
            for (int i = 0; i < children.getLength(); i++) {
                Node child = children.item(i);

                switch (child.getNodeType()) {

                case Node.ELEMENT_NODE:
                    hasChildElements = true;
                    if (i == 0) {
                        out.write(lSep);
                    }
                    write((Element) child, out, indent + 1, indentWith);
                    break;

                case Node.TEXT_NODE:
                    out.write(encode(child.getNodeValue()));
                    break;

                case Node.COMMENT_NODE:
                    out.write("<!--");
                    out.write(encode(child.getNodeValue()));
                    out.write("-->");
                    break;

                case Node.CDATA_SECTION_NODE:
                    out.write("<![CDATA[");
                    out.write(encodedata(((Text) child).getData()));
                    out.write("]]>");
                    break;

                case Node.ENTITY_REFERENCE_NODE:
                    out.write('&');
                    out.write(child.getNodeName());
                    out.write(';');
                    break;

                case Node.PROCESSING_INSTRUCTION_NODE:
                    out.write("<?");
                    out.write(child.getNodeName());
                    String data = child.getNodeValue();
                    if (data != null && data.length() > 0) {
                        out.write(' ');
                        out.write(data);
                    }
                    out.write("?>");
                    break;
                default:
                    // Do nothing
                }
            }
            closeElement(element, out, indent, indentWith, hasChildElements);
        }
    }

    /**
     * Writes the opening tag - including all attributes -
     * corresponding to a DOM element.
     *
     * @param element the DOM element to write
     * @param out where to send the output
     * @param indent number of
     * @param indentWith string that should be used to indent the
     * corresponding tag.
     * @throws IOException if an error happens while writing to the stream.
     */
    public void openElement(Element element, Writer out, int indent,
                            String indentWith)
        throws IOException {
        openElement(element, out, indent, indentWith, true);
    }

    /**
     * Writes the opening tag - including all attributes -
     * corresponding to a DOM element.
     *
     * @param element the DOM element to write
     * @param out where to send the output
     * @param indent number of
     * @param indentWith string that should be used to indent the
     * corresponding tag.
     * @param hasChildren whether this element has children.
     * @throws IOException if an error happens while writing to the stream.
     * @since Ant 1.7
     */
    public void openElement(Element element, Writer out, int indent,
                            String indentWith, boolean hasChildren)
        throws IOException {
        // Write indent characters
        for (int i = 0; i < indent; i++) {
            out.write(indentWith);
        }