Ant example source code file (DOMElementWriter.java)

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

Java - Ant tags/keywords

arraylist, arraylist, dom, domelementwriter, hashmap, io, ioexception, ioexception, iterator, ns, string, string, stringbuffer, util, writer, xmlnamespacepolicy, xmlnamespacepolicy

The DOMElementWriter.java source code

/*
 *  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 {

    /** prefix for genefrated 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 <?xml version='1.0' encoding='UTF-8'?> 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);
        }

        // Write element
        out.write("<");
        if (namespacePolicy.qualifyElements) {
            String uri = getNamespaceURI(element);
            String prefix = (String) nsPrefixMap.get(uri);
            if (prefix == null) {
                if (nsPrefixMap.isEmpty()) {
                    // steal default namespace
                    prefix = "";
                } else {
                    prefix = NS + (nextPrefix++);
                }
                nsPrefixMap.put(uri, prefix);
                addNSDefinition(element, uri);
            }
            if (!"".equals(prefix)) {
                out.write(prefix);
                out.write(":");
            }
        }
        out.write(element.getTagName());

        // Write attributes
        NamedNodeMap attrs = element.getAttributes();
        for (int i = 0; i < attrs.getLength(); i++) {
            Attr attr = (Attr) attrs.item(i);
            out.write(" ");
            if (namespacePolicy.qualifyAttributes) {
                String uri = getNamespaceURI(attr);
                String prefix = (String) nsPrefixMap.get(uri);
                if (prefix == null) {
                    prefix = NS + (nextPrefix++);
                    nsPrefixMap.put(uri, prefix);
                    addNSDefinition(element, uri);
                }
                out.write(prefix);
                out.write(":");
            }
            out.write(attr.getName());
            out.write("=\"");
            out.write(encode(attr.getValue()));
            out.write("\"");
        }

        // write namespace declarations
        ArrayList al = (ArrayList) nsURIByElement.get(element);
        if (al != null) {
            Iterator iter = al.iterator();
            while (iter.hasNext()) {
                String uri = (String) iter.next();
                String prefix = (String) nsPrefixMap.get(uri);
                out.write(" xmlns");
                if (!"".equals(prefix)) {
                    out.write(":");
                    out.write(prefix);
                }
                out.write("=\"");
                out.write(uri);
                out.write("\"");
            }
        }

        if (hasChildren) {
            out.write(">");
        } else {
            removeNSDefinitions(element);
            out.write(" />");
            out.write(lSep);
            out.flush();
        }
    }

    /**
     * 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.
     * @param hasChildren if true indent.
     * @throws IOException if an error happens while writing to the stream.
     */
    public void closeElement(Element element, Writer out, int indent,
                             String indentWith, boolean hasChildren)
        throws IOException {
        // If we had child elements, we need to indent before we close
        // the element, otherwise we're on the same line and don't need
        // to indent
        if (hasChildren) {
            for (int i = 0; i < indent; i++) {
                out.write(indentWith);
            }
        }

        // Write element close
        out.write("</");
        if (namespacePolicy.qualifyElements) {
            String uri = getNamespaceURI(element);
            String prefix = (String) nsPrefixMap.get(uri);
            if (prefix != null && !"".equals(prefix)) {
                out.write(prefix);
                out.write(":");
            }
            removeNSDefinitions(element);
        }
        out.write(element.getTagName());
        out.write(">");
        out.write(lSep);
        out.flush();
    }

    /**
     * Escape <, > & ', " as their entities and
     * drop characters that are illegal in XML documents.
     * @param value the string to encode.
     * @return the encoded string.
     */
    public String encode(String value) {
        StringBuffer sb = new StringBuffer();
        int len = value.length();
        for (int i = 0; i < len; i++) {
            char c = value.charAt(i);
            switch (c) {
            case '<':
                sb.append("<");
                break;
            case '>':
                sb.append(">");
                break;
            case '\'':
                sb.append("'");
                break;
            case '\"':
                sb.append(""");
                break;
            case '&':
                int nextSemi = value.indexOf(";", i);
                if (nextSemi < 0
                    || !isReference(value.substring(i, nextSemi + 1))) {
                    sb.append("&");
                } else {
                    sb.append('&');
                }
                break;
            default:
                if (isLegalCharacter(c)) {
                    sb.append(c);
                }
                break;
            }
        }
        return sb.substring(0);
    }

    /**
     * Drop characters that are illegal in XML documents.
     *
     * <p>Also ensure that we are not including an ]]>
     * marker by replacing that sequence with
     * <code>&#x5d;&#x5d;&gt;.

     *
     * <p>See XML 1.0 2.2 .

     * @param value the value to be encoded.
     * @return the encoded value.

     */
    public String encodedata(final String value) {
        StringBuffer sb = new StringBuffer();
        int len = value.length();
        for (int i = 0; i < len; ++i) {
            char c = value.charAt(i);
            if (isLegalCharacter(c)) {
                sb.append(c);
            }
        }

        String result = sb.substring(0);
        int cdEnd = result.indexOf("]]>");
        while (cdEnd != -1) {
            sb.setLength(cdEnd);
            sb.append("]]>")
                .append(result.substring(cdEnd + 3));
            result = sb.substring(0);
            cdEnd = result.indexOf("]]>");
        }

        return result;
    }

    /**
     * Is the given argument a character or entity reference?
     * @param ent the value to be checked.
     * @return true if it is an entity.
     */
    public boolean isReference(String ent) {
        if (!(ent.charAt(0) == '&') || !ent.endsWith(";")) {
            return false;
        }

        if (ent.charAt(1) == '#') {
            if (ent.charAt(2) == 'x') {
                try {
                    Integer.parseInt(ent.substring(3, ent.length() - 1), 16);
                    return true;
                } catch (NumberFormatException nfe) {
                    return false;
                }
            } else {
                try {
                    Integer.parseInt(ent.substring(2, ent.length() - 1));
                    return true;
                } catch (NumberFormatException nfe) {
                    return false;
                }
            }
        }

        String name = ent.substring(1, ent.length() - 1);
        for (int i = 0; i < knownEntities.length; i++) {
            if (name.equals(knownEntities[i])) {
                return true;
            }
        }
        return false;
    }

    /**
     * Is the given character allowed inside an XML document?
     *
     * <p>See XML 1.0 2.2 
     * @param c the character to test.
     * @return true if the character is allowed.
     * @since 1.10, Ant 1.5
     */
    public boolean isLegalCharacter(char c) {
        if (c == 0x9 || c == 0xA || c == 0xD) {
            return true;
        } else if (c < 0x20) {
            return false;
        } else if (c <= 0xD7FF) {
            return true;
        } else if (c < 0xE000) {
            return false;
        } else if (c <= 0xFFFD) {
            return true;
        }
        return false;
    }

    private void removeNSDefinitions(Element element) {
        ArrayList al = (ArrayList) nsURIByElement.get(element);
        if (al != null) {
            Iterator iter = al.iterator();
            while (iter.hasNext()) {
                nsPrefixMap.remove(iter.next());
            }
            nsURIByElement.remove(element);
        }
    }

    private void addNSDefinition(Element element, String uri) {
        ArrayList al = (ArrayList) nsURIByElement.get(element);
        if (al == null) {
            al = new ArrayList();
            nsURIByElement.put(element, al);
        }
        al.add(uri);
    }

    private static String getNamespaceURI(Node n) {
        String uri = n.getNamespaceURI();
        if (uri == null) {
            // FIXME: Is "No Namespace is Empty Namespace" really OK?
            uri = "";
        }
        return uri;
    }
}