eionet.webq.converter.XmlSchemaExtractor.java Source code

Introduction

Here is the source code for eionet.webq.converter.XmlSchemaExtractor.java

Source

/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Web Questionnaires 2
 *
 * The Initial Owner of the Original Code is European Environment
 * Agency. Portions created by TripleDev are Copyright
 * (C) European Environment Agency.  All Rights Reserved.
 *
 * Contributor(s):
 *        Anton Dmitrijev
 */
package eionet.webq.converter;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Component;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.ByteArrayInputStream;

import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

/**
 * Extracts xml schema from provided source.
 */
@Component
public class XmlSchemaExtractor {
    /**
     * Xsi namespace URI.
     */
    private static final String XSI_NAMESPACE_URI = "http://www.w3.org/2001/XMLSchema-instance";
    /**
     * Logger for this class.
     */
    private static final Logger LOGGER = Logger.getLogger(XmlSchemaExtractor.class);

    /**
     *
     *
     * @param bytes uploaded file bytes
     * @return
     */
    /**
     * Extracts {@code @xsi:noNamespaceSchemaLocation} or {@code @xsi:schemaLocation} attribute value from xml root element.
     *
     * @param source source to be searched.
     * @return {@code @xsi:noNamespaceSchemaLocation} or {@code @xsi:schemaLocation} attribute value, default {@code null}
     */
    public String extractXmlSchema(byte[] source) {
        XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
        ByteArrayInputStream bais = new ByteArrayInputStream(source);
        XMLStreamReader xmlStreamReader = null;
        try {
            xmlStreamReader = xmlInputFactory.createXMLStreamReader(bais);
            while (xmlStreamReader.hasNext()) {
                if (xmlStreamReader.next() == START_ELEMENT) {
                    return StringUtils.defaultString(
                            parseNoNamespaceSchemaLocation(xmlStreamReader.getAttributeValue(XSI_NAMESPACE_URI,
                                    "noNamespaceSchemaLocation")),
                            parseSchemaLocation(
                                    xmlStreamReader.getAttributeValue(XSI_NAMESPACE_URI, "schemaLocation")));
                }
            }
        } catch (Exception e) {
            LOGGER.warn("exception thrown during extracting xml schema", e);
        } finally {
            IOUtils.closeQuietly(bais);
            if (xmlStreamReader != null) {
                try {
                    xmlStreamReader.close();
                } catch (XMLStreamException e) {
                    LOGGER.warn("unable to close xml stream", e);
                }
            }
        }
        return null;
    }

    /**
     * Parse noNamespaceSchemaLocation attribute and extract space delimited schema URLs.
     *
     * @param noNamespaceSchemaLocation Schema location string
     * @return Space delimited schema URLs
     */
    private String parseNoNamespaceSchemaLocation(String noNamespaceSchemaLocation) {

        if (StringUtils.isBlank(noNamespaceSchemaLocation)) {
            return noNamespaceSchemaLocation;
        }

        String[] split = StringUtils.split(noNamespaceSchemaLocation);
        return StringUtils.join(split, ' ');
    }

    /**
     * Parse schemaLocation attribute and extract schema URLs without namespace references.
     *
     * @param schemaLocation Schema location string containing space delimited namespace + schema URL pairs.
     * @return Space delimited schema URLs without namespace references.
     */
    private String parseSchemaLocation(String schemaLocation) {

        if (StringUtils.isBlank(schemaLocation)) {
            return schemaLocation;
        }

        StringBuilder sb = new StringBuilder();
        String[] split = StringUtils.split(schemaLocation);
        for (int i = 0; i < split.length; i++) {
            if (i % 2 != 0) {
                sb.append(" ").append(split[i]);
            }
        }
        return sb.toString().trim();
    }
}