org.dswarm.xmlenhancer.XMLEnhancer.java Source code

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Here is the source code for org.dswarm.xmlenhancer.XMLEnhancer.java

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/**
 * Copyright (C) 2013  2016 SLUB Dresden & Avantgarde Labs GmbH (<code@dswarm.org>)
 *
 * 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 org.dswarm.xmlenhancer;

import java.io.IOException;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

import org.apache.commons.lang3.StringEscapeUtils;
import org.jsoup.nodes.Attributes;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.nodes.Entities;
import org.jsoup.nodes.Node;
import org.jsoup.nodes.TextNode;
import org.jsoup.parser.Parser;

/**
 * Tries to enhance (maybe) invalid XML as much as possible.<br/>
 * Currently, it tries to the following:<br/>
 * - add CDATA to all texts of XML Elements<br/>
 *
 * @author tgaengler
 */
public class XMLEnhancer {

    private static final String DUMMY_BASE_URI = "http://example.com";
    private static final String UTF_8 = "UTF-8";
    private static final String START_CDATA = "<![CDATA[";
    private static final String END_CDATA = "]]>";

    public static void enhanceXML(final String inputFileName, final String outputFileName) throws IOException {

        final Path inputFilePath = Paths.get(inputFileName);
        final byte[] inputBytes = Files.readAllBytes(inputFilePath);
        final String inputString = new String(inputBytes, StandardCharsets.UTF_8);

        final List<Node> nodes = Parser.parseXmlFragment(inputString, DUMMY_BASE_URI);

        enhanceNodes(nodes);

        final Path outputFilePath = Paths.get(outputFileName);
        final String outResource = outputFilePath.toString();

        final PrintWriter out = new PrintWriter(outResource, UTF_8);

        nodes.forEach(node -> unescapeEntity(out, node));

        out.flush();
        out.close();
    }

    private static void unescapeEntity(final PrintWriter out, final Node node) {

        node.ownerDocument().outputSettings().escapeMode(Entities.EscapeMode.xhtml)
                .syntax(Document.OutputSettings.Syntax.xml).prettyPrint(false);

        if (node instanceof TextNode) {

            final TextNode textNode = (TextNode) node;

            final String wholeText = textNode.getWholeText();

            out.print(wholeText);

            return;
        }

        final String nodeString = node.toString();
        final String unescapedNodeString = Parser.unescapeEntities(nodeString, true);

        out.print(unescapedNodeString);
    }

    private static void enhanceNodes(final List<Node> nodes) {

        nodes.forEach(node -> {

            if (node instanceof Element) {

                Element element = (Element) node;

                final Attributes attributes = element.attributes();

                enhanceAttributes(attributes);

                final List<Node> childNodes = element.childNodes();

                enhanceNodes(childNodes);

                return;
            }

            if (node instanceof TextNode) {

                enhanceTextNode(node);
            }
        });
    }

    private static void enhanceAttributes(final Attributes attributes) {

        attributes.forEach(attribute -> {

            final String value = attribute.getValue();

            String escapedValue = StringEscapeUtils.escapeXml11(value);

            attribute.setValue(escapedValue);
        });
    }

    private static void enhanceTextNode(final Node node) {

        final TextNode textNode = (TextNode) node;
        final String wholeText = textNode.getWholeText();
        final String text = node.toString();

        if (text.trim().isEmpty()) {

            return;
        }

        if (wholeText.startsWith(START_CDATA)) {

            // do not add CDATA multiple times

            return;
        }

        final String alignedText = alignTextWithWholeText(wholeText, text);

        final String unescapeEntities = String.format("%s%s%s", START_CDATA, alignedText, END_CDATA);

        textNode.text(unescapeEntities);
    }

    private static String alignTextWithWholeText(final String wholeText, final String text) {

        // align start and ending between whole text and text
        String cuttedStartText = text;

        int j = 0;

        for (int i = 0; i < text.length(); i++) {

            final char currentTextCharacter = text.charAt(i);
            final char currentWholeTextCharacter = wholeText.charAt(j);

            if (currentTextCharacter == currentWholeTextCharacter) {

                if (currentTextCharacter != '\n' && currentTextCharacter != '\r' && currentTextCharacter != '\t') {

                    // hit first real character, now move back to the point where both matched first

                    cuttedStartText = text.substring(i - j, text.length());

                    break;
                }

                j++;
            }
        }

        return cuttedStartText;
    }
}