134 lines
3.9 KiB
Java
134 lines
3.9 KiB
Java
package eu.dnetlib.data.collector.plugins.oaisets;
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import java.io.StringReader;
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import java.util.Iterator;
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import java.util.Queue;
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import java.util.Set;
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import java.util.concurrent.PriorityBlockingQueue;
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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.dom4j.Document;
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import org.dom4j.DocumentException;
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import org.dom4j.Element;
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import org.dom4j.Node;
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import org.dom4j.io.SAXReader;
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import com.google.common.collect.Sets;
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import eu.dnetlib.data.collector.plugins.HttpConnector;
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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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public class OaiSetsIterator implements Iterator<String> {
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private static final Log log = LogFactory.getLog(OaiSetsIterator.class);
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private Queue<String> queue = new PriorityBlockingQueue<String>();
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private SAXReader reader = new SAXReader();
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private String baseUrl;
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private String token;
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private boolean started;
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private HttpConnector httpConnector;
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private Set<String> setsAlreadySeen = Sets.newHashSet();
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public OaiSetsIterator(final String baseUrl, final HttpConnector httpConnector) {
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this.baseUrl = baseUrl;
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this.started = false;
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this.httpConnector = httpConnector;
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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 (CollectorServiceException e) {
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throw new RuntimeException(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 (CollectorServiceException e) {
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throw new RuntimeException(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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private String firstPage() throws CollectorServiceException {
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final String url = baseUrl + "?verb=ListSets";
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log.info("Start harvesting using url: " + url);
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return downloadPage(url);
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}
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private String otherPages(final String resumptionToken) throws CollectorServiceException {
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return downloadPage(baseUrl + "?verb=ListSets&resumptionToken=" + resumptionToken);
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}
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private String downloadPage(final String url) throws CollectorServiceException {
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final String xml = httpConnector.getInputSource(url);
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Document doc;
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try {
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doc = reader.read(new StringReader(xml));
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} catch (DocumentException e) {
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log.warn("Error parsing xml, I try to clean it: " + xml, e);
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final String cleaned = XmlCleaner.cleanAllEntities(xml);
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try {
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doc = reader.read(new StringReader(cleaned));
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} catch (DocumentException e1) {
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throw new CollectorServiceException("Error parsing cleaned document:" + cleaned, e1);
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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");
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if ("noRecordsMatch".equalsIgnoreCase(code.trim())) {
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log.warn("noRecordsMatch for oai call: " + url);
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return null;
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} else throw new CollectorServiceException(code + " - " + errorNode.getText());
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}
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boolean sawAllSets = true;
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for (Object o : doc.selectNodes("//*[local-name()='ListSets']/*[local-name()='set']")) {
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String set = ((Element) o).valueOf("./*[local-name()='setSpec']");
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if (!setsAlreadySeen.contains(set)) {
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sawAllSets = false;
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setsAlreadySeen.add(set);
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queue.add(((Node) o).asXML());
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}
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}
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if (sawAllSets) {
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log.warn("URL " + baseUrl + " keeps returning the same OAI sets. Please contact the repo admin.");
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System.out.println("URL " + baseUrl + " keeps returning the same OAI sets. Please contact the repo admin.");
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return null;
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} else return doc.valueOf("//*[local-name()='resumptionToken']");
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}
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}
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