344 lines
12 KiB
Java
344 lines
12 KiB
Java
/**
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* log.debug(...) equal to log.trace(...) in the application-logs
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* <p>
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* known bug: at resumptionType 'discover' if the (resultTotal % resultSizeValue) == 0 the collecting fails -> change the resultSizeValue
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*/
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package eu.dnetlib.data.collector.plugins.rest;
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import java.io.InputStream;
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import java.io.StringWriter;
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import java.net.URL;
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import java.util.Iterator;
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import java.util.Queue;
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import java.util.concurrent.PriorityBlockingQueue;
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import javax.xml.transform.OutputKeys;
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import javax.xml.transform.Transformer;
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import javax.xml.transform.TransformerConfigurationException;
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import javax.xml.transform.TransformerFactory;
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import javax.xml.transform.dom.DOMSource;
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import javax.xml.transform.stream.StreamResult;
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import javax.xml.xpath.*;
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import eu.dnetlib.data.collector.plugins.oai.engine.XmlCleaner;
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import eu.dnetlib.data.collector.rmi.CollectorServiceException;
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import org.apache.commons.io.IOUtils;
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import org.apache.commons.lang3.StringUtils;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.w3c.dom.Node;
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import org.w3c.dom.NodeList;
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import org.xml.sax.InputSource;
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/**
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* @author Jochen Schirrwagen, Aenne Loehden, Andreas Czerniak
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* @date 2018-09-03
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*
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*/
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public class RestIterator implements Iterator<String> {
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// TODO: clean up the comments of replaced source code
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private static final Log log = LogFactory.getLog(RestIterator.class); // NOPMD by marko on 11/24/08 5:02 PM
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private static final String wrapName = "recordWrap";
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private String baseUrl;
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private String resumptionType;
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private String resumptionParam;
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private String resultFormatValue;
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private String queryParams;
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private int resultSizeValue;
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private int resumptionInt = 0; // integer resumption token (first record to harvest)
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private int resultTotal = -1;
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private String resumptionStr = Integer.toString(resumptionInt); // string resumption token (first record to harvest or token scanned from results)
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private InputStream resultStream;
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private Transformer transformer;
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private XPath xpath;
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private String query;
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private XPathExpression xprResultTotalPath;
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private XPathExpression xprResumptionPath;
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private XPathExpression xprEntity;
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private String queryFormat;
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private String querySize;
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private Queue<String> recordQueue = new PriorityBlockingQueue<String>();
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private int discoverResultSize = 0;
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private int pagination = 1;
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public RestIterator(
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final String baseUrl,
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final String resumptionType,
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final String resumptionParam,
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final String resumptionXpath,
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final String resultTotalXpath,
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final String resultFormatParam,
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final String resultFormatValue,
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final String resultSizeParam,
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final String resultSizeValueStr,
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final String queryParams,
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final String entityXpath
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) {
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this.baseUrl = baseUrl;
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this.resumptionType = resumptionType;
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this.resumptionParam = resumptionParam;
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this.resultFormatValue = resultFormatValue;
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this.queryParams = queryParams;
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this.resultSizeValue = Integer.valueOf(resultSizeValueStr);
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queryFormat = StringUtils.isNotBlank(resultFormatParam) ? "&" + resultFormatParam + "=" + resultFormatValue : "";
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querySize = StringUtils.isNotBlank(resultSizeParam) ? "&" + resultSizeParam + "=" + resultSizeValueStr : "";
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try {
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initXmlTransformation(resultTotalXpath, resumptionXpath, entityXpath);
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} catch (Exception e) {
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throw new IllegalStateException("xml transformation init failed: " + e.getMessage());
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}
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initQueue();
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}
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private void initXmlTransformation(String resultTotalXpath, String resumptionXpath, String entityXpath)
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throws TransformerConfigurationException, XPathExpressionException {
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transformer = TransformerFactory.newInstance().newTransformer();
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transformer.setOutputProperty(OutputKeys.INDENT, "yes");
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transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "3");
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xpath = XPathFactory.newInstance().newXPath();
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xprResultTotalPath = xpath.compile(resultTotalXpath);
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xprResumptionPath = xpath.compile(StringUtils.isBlank(resumptionXpath) ? "/" : resumptionXpath);
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xprEntity = xpath.compile(entityXpath);
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}
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private void initQueue() {
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query = baseUrl + "?" + queryParams + querySize + queryFormat;
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}
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private void disconnect() {
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// TODO close inputstream
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}
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/* (non-Javadoc)
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* @see java.util.Iterator#hasNext()
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*/
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@Override
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public boolean hasNext() {
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if (recordQueue.isEmpty() && query.isEmpty()) {
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disconnect();
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return false;
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} else {
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return true;
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}
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}
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/* (non-Javadoc)
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* @see java.util.Iterator#next()
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*/
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@Override
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public String next() {
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synchronized (recordQueue) {
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while (recordQueue.isEmpty() && !query.isEmpty()) {
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try {
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log.info("get Query: " + query);
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query = downloadPage(query);
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log.debug("next queryURL from downloadPage(): " + query);
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} catch (CollectorServiceException e) {
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log.debug("CollectorPlugin.next()-Exception: " + e);
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throw new RuntimeException(e);
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}
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}
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return recordQueue.poll();
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}
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}
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/*
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* download page and return nextQuery
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*/
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private String downloadPage(String query) throws CollectorServiceException {
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String resultJson;
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String resultXml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
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String nextQuery = "";
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String emptyXml = resultXml + "<" + wrapName + "></" + wrapName + ">";
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Node resultNode = null;
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NodeList nodeList = null;
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String qUrlArgument = "";
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int urlOldResumptionSize = 0;
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try {
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URL qUrl = new URL(query);
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resultStream = qUrl.openStream();
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if ("json".equals(resultFormatValue.toLowerCase())) {
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resultJson = IOUtils.toString(resultStream, "UTF-8");
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resultJson = syntaxConvertJsonKeyNamens(resultJson);
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org.json.JSONObject jsonObject = new org.json.JSONObject(resultJson);
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resultXml += org.json.XML.toString(jsonObject, wrapName); // wrap xml in single root element
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log.trace("before inputStream: " + resultXml);
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resultXml = XmlCleaner.cleanAllEntities(resultXml);
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log.trace("after cleaning: " + resultXml);
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resultStream = IOUtils.toInputStream(resultXml, "UTF-8");
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}
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if (!(emptyXml.toLowerCase()).equals(resultXml.toLowerCase())) {
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resultNode = (Node) xpath.evaluate("/", new InputSource(resultStream), XPathConstants.NODE);
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nodeList = (NodeList) xprEntity.evaluate(resultNode, XPathConstants.NODESET);
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log.debug("nodeList.length: " + nodeList.getLength());
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for (int i = 0; i < nodeList.getLength(); i++) {
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StringWriter sw = new StringWriter();
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transformer.transform(new DOMSource(nodeList.item(i)), new StreamResult(sw));
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recordQueue.add(sw.toString());
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}
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} else { log.info("resultXml is equal with emptyXml"); }
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resumptionInt += resultSizeValue;
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switch (resumptionType.toLowerCase()) {
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case "scan": // read of resumptionToken , evaluate next results, e.g. OAI, iterate over items
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resumptionStr = xprResumptionPath.evaluate(resultNode);
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break;
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case "count": // begin at one step for all records, iterate over items
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resumptionStr = Integer.toString(resumptionInt);
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break;
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case "discover": // size of result items unknown, iterate over items (for openDOAR - 201808)
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if (resultSizeValue < 2) {throw new CollectorServiceException("Mode: discover, Param 'resultSizeValue' is less than 2");}
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qUrlArgument = qUrl.getQuery();
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String[] arrayQUrlArgument = qUrlArgument.split("&");
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for (String arrayUrlArgStr : arrayQUrlArgument) {
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if (arrayUrlArgStr.startsWith(resumptionParam)) {
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String[] resumptionKeyValue = arrayUrlArgStr.split("=");
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urlOldResumptionSize = Integer.parseInt(resumptionKeyValue[1]);
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log.debug("discover OldResumptionSize from Url: " + urlOldResumptionSize);
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}
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}
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if (((emptyXml.toLowerCase()).equals(resultXml.toLowerCase()))
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|| ((nodeList != null) && (nodeList.getLength() < resultSizeValue))
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) {
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// resumptionStr = "";
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if (nodeList != null) { discoverResultSize += nodeList.getLength(); }
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resultTotal = discoverResultSize;
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} else {
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resumptionStr = Integer.toString(resumptionInt);
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resultTotal = resumptionInt + 1;
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if (nodeList != null) { discoverResultSize += nodeList.getLength(); }
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}
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log.info("discoverResultSize: " + discoverResultSize);
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break;
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case "pagination":
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case "page": // pagination, iterate over pages
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pagination += 1;
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if (nodeList != null) {
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discoverResultSize += nodeList.getLength();
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} else {
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resultTotal = discoverResultSize;
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pagination = discoverResultSize;
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}
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resumptionInt = pagination;
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resumptionStr = Integer.toString(resumptionInt);
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break;
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default: // otherwise: abort
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// resultTotal = resumptionInt;
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break;
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}
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if (resultTotal == -1) {
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resultTotal = Integer.parseInt(xprResultTotalPath.evaluate(resultNode));
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if (resumptionType.toLowerCase().equals("page")) { resultTotal += 1; } // to correct the upper bound
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log.info("resultTotal was -1 is now: " + resultTotal);
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}
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log.info("resultTotal: " + resultTotal);
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log.info("resInt: " + resumptionInt);
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if (resumptionInt < resultTotal) {
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nextQuery = baseUrl + "?" + queryParams + querySize + "&" + resumptionParam + "=" + resumptionStr + queryFormat;
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} else
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nextQuery = "";
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log.debug("nextQueryUrl: " + nextQuery);
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return nextQuery;
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} catch (Exception e) {
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log.error(e);
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throw new IllegalStateException("collection failed: " + e.getMessage());
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}
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}
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/**
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* convert in JSON-KeyName 'whitespace(s)' to '_' and '/' to '_', '(' and ')' to ''
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* check W3C XML syntax: https://www.w3.org/TR/2006/REC-xml11-20060816/#sec-starttags for valid tag names
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* and work-around for the JSON to XML converting of org.json.XML-package.
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*
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* known bugs: doesn't prevent "key name":" ["sexy name",": penari","erotic dance"],
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*
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* @param jsonInput
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* @return convertedJsonKeynameOutput
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*/
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private String syntaxConvertJsonKeyNamens(String jsonInput) {
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log.trace("before convertJsonKeyNames: " + jsonInput);
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// pre-clean json - rid spaces of element names (misinterpreted as elements with attributes in xml)
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// replace ' 's in JSON Namens with '_'
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while (jsonInput.matches(".*\"([^\"]*)\\s+([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*)\\s+([^\"]*)\":", "\"$1_$2\":");
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}
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// replace forward-slash (sign '/' ) in JSON Names with '_'
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while (jsonInput.matches(".*\"([^\"]*)/([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*)/([^\"]*)\":", "\"$1_$2\":");
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}
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// replace '(' in JSON Names with ''
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while (jsonInput.matches(".*\"([^\"]*)[(]([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*)[(]([^\"]*)\":", "\"$1$2\":");
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}
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// replace ')' in JSON Names with ''
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while (jsonInput.matches(".*\"([^\"]*)[)]([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*)[)]([^\"]*)\":", "\"$1$2\":");
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}
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// replace startNumbers in JSON Keynames with 'n_'
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while (jsonInput.matches(".*\"([^\"][0-9])([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"][0-9])([^\"]*)\":", "\"n_$1$2\":");
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}
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// replace ':' between number like '2018-08-28T11:05:00Z' in JSON keynames with ''
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while (jsonInput.matches(".*\"([^\"]*[0-9]):([0-9][^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*[0-9]):([0-9][^\"]*)\":", "\"$1$2\":");
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}
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// replace ',' in JSON Keynames with '.' to prevent , in xml tagnames.
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// while (jsonInput.matches(".*\"([^\"]*),([^\"]*)\":.*")) {
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// jsonInput = jsonInput.replaceAll("\"([^\"]*),([^\"]*)\":", "\"$1.$2\":");
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// }
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// replace '=' in JSON Keynames with '-'
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while (jsonInput.matches(".*\"([^\"]*)=([^\"]*)\":.*")) {
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jsonInput = jsonInput.replaceAll("\"([^\"]*)=([^\"]*)\":", "\"$1-$2\":");
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}
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log.trace("after syntaxConvertJsonKeyNames: " + jsonInput);
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return jsonInput;
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}
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/**
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*
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* https://www.w3.org/TR/REC-xml/#charencoding shows character enoding in entities
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* *
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* @param bufferStr - XML string
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* @return
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*/
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private static String cleanUnwantedJsonCharsInXmlTagnames(String bufferStr) {
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while (bufferStr.matches(".*<([^<>].*),(.)>.*")) {
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bufferStr = bufferStr.replaceAll("<([^<>.*),(.*)>", "<$1$2>");
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}
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// replace [#x10-#x1f] with ''
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// while (bufferStr.matches(".*[0-9a-f].*")) {
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// bufferStr = bufferStr.replaceAll("([0-9a-fA-F])", "");
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// }
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return bufferStr;
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}
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}
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