209 lines
6.0 KiB
Java
209 lines
6.0 KiB
Java
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package eu.dnetlib.dhp.collection.plugin.oai;
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import java.io.IOException;
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import java.io.StringWriter;
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import java.io.UnsupportedEncodingException;
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import java.net.URLEncoder;
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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 org.apache.commons.lang.StringUtils;
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import org.dom4j.Document;
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import org.dom4j.DocumentException;
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import org.dom4j.DocumentHelper;
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import org.dom4j.Node;
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import org.dom4j.io.OutputFormat;
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import org.dom4j.io.XMLWriter;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import eu.dnetlib.dhp.collection.XmlCleaner;
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import eu.dnetlib.dhp.common.aggregation.AggregatorReport;
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import eu.dnetlib.dhp.common.collection.CollectorException;
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import eu.dnetlib.dhp.common.collection.HttpConnector2;
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public class OaiIterator implements Iterator<String> {
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private static final Logger log = LoggerFactory.getLogger(OaiIterator.class);
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private static final String REPORT_PREFIX = "oai:";
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public static final String UTF_8 = "UTF-8";
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private final Queue<String> queue = new PriorityBlockingQueue<>();
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private final String baseUrl;
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private final String set;
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private final String mdFormat;
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private final String fromDate;
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private final String untilDate;
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private String token;
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private boolean started;
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private final HttpConnector2 httpConnector;
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private final AggregatorReport report;
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public OaiIterator(
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final String baseUrl,
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final String mdFormat,
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final String set,
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final String fromDate,
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final String untilDate,
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final HttpConnector2 httpConnector,
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final AggregatorReport report) {
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this.baseUrl = baseUrl;
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this.mdFormat = mdFormat;
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this.set = set;
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this.fromDate = fromDate;
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this.untilDate = untilDate;
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this.started = false;
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this.httpConnector = httpConnector;
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this.report = report;
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}
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private void verifyStarted() {
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if (!this.started) {
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this.started = true;
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try {
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this.token = firstPage();
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} catch (final CollectorException e) {
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throw new IllegalStateException(e);
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}
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}
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}
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@Override
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public boolean hasNext() {
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synchronized (queue) {
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verifyStarted();
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return !queue.isEmpty();
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}
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}
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@Override
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public String next() {
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synchronized (queue) {
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verifyStarted();
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final String res = queue.poll();
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while (queue.isEmpty() && token != null && !token.isEmpty()) {
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try {
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token = otherPages(token);
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} catch (final CollectorException e) {
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throw new IllegalStateException(e);
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}
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}
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return res;
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}
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}
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@Override
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public void remove() {
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throw new UnsupportedOperationException();
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}
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private String firstPage() throws CollectorException {
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try {
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String url = baseUrl + "?verb=ListRecords&metadataPrefix=" + URLEncoder.encode(mdFormat, UTF_8);
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if (set != null && !set.isEmpty()) {
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url += "&set=" + URLEncoder.encode(set, UTF_8);
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}
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if (fromDate != null && (fromDate.matches(OaiCollectorPlugin.DATE_REGEX)
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|| fromDate.matches(OaiCollectorPlugin.UTC_DATETIME_REGEX))) {
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url += "&from=" + URLEncoder.encode(fromDate, UTF_8);
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}
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if (untilDate != null && (untilDate.matches(OaiCollectorPlugin.DATE_REGEX)
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|| untilDate.matches(OaiCollectorPlugin.UTC_DATETIME_REGEX))) {
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url += "&until=" + URLEncoder.encode(untilDate, UTF_8);
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}
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log.info("Start harvesting using url: {}", url);
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return downloadPage(url);
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} catch (final UnsupportedEncodingException e) {
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report.put(e.getClass().getName(), e.getMessage());
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throw new CollectorException(e);
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}
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}
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private String extractResumptionToken(final String xml) {
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final String s = StringUtils.substringAfter(xml, "<resumptionToken");
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if (s == null) {
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return null;
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}
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final String result = StringUtils.substringBetween(s, ">", "</");
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if (result == null) {
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return null;
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}
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return result.trim();
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}
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private String otherPages(final String resumptionToken) throws CollectorException {
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try {
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return downloadPage(
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baseUrl
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+ "?verb=ListRecords&resumptionToken="
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+ URLEncoder.encode(resumptionToken, UTF_8));
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} catch (final UnsupportedEncodingException e) {
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report.put(e.getClass().getName(), e.getMessage());
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throw new CollectorException(e);
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}
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}
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private String downloadPage(final String url) throws CollectorException {
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final String xml = httpConnector.getInputSource(url, report);
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Document doc;
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try {
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doc = DocumentHelper.parseText(xml);
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} catch (final DocumentException e) {
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log.warn("Error parsing xml, I try to clean it. {}", e.getMessage());
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report.put(e.getClass().getName(), e.getMessage());
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final String cleaned = XmlCleaner.cleanAllEntities(xml);
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try {
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doc = DocumentHelper.parseText(xml);
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} catch (final DocumentException e1) {
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final String resumptionToken = extractResumptionToken(xml);
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if (resumptionToken == null) {
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report.put(e1.getClass().getName(), e1.getMessage());
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throw new CollectorException("Error parsing cleaned document:\n" + cleaned, e1);
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}
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return resumptionToken;
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}
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}
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final Node errorNode = doc.selectSingleNode("/*[local-name()='OAI-PMH']/*[local-name()='error']");
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if (errorNode != null) {
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final String code = errorNode.valueOf("@code").trim();
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if ("noRecordsMatch".equalsIgnoreCase(code)) {
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final String msg = "noRecordsMatch for oai call : " + url;
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log.warn(msg);
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report.put(REPORT_PREFIX + code, msg);
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return null;
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} else {
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final String msg = code + " - " + errorNode.getText();
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report.put(REPORT_PREFIX + "error", msg);
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throw new CollectorException(msg);
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}
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}
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for (final Object o : doc.selectNodes("//*[local-name()='ListRecords']/*[local-name()='record']")) {
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final StringWriter sw = new StringWriter();
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final XMLWriter writer = new XMLWriter(sw, OutputFormat.createPrettyPrint());
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try {
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writer.write((Node) o);
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queue.add(sw.toString());
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} catch (IOException e) {
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report.put(e.getClass().getName(), e.getMessage());
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throw new CollectorException("Error parsing XML record:\n" + ((Node) o).asXML(), e);
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}
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}
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return doc.valueOf("//*[local-name()='resumptionToken']");
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}
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public AggregatorReport getReport() {
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return report;
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}
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}
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