Java tutorial
/* * GeoTools - The Open Source Java GIS Toolkit * http://geotools.org * * (C) 2014, Open Source Geospatial Foundation (OSGeo) * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; * version 2.1 of the License. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. */ package org.geotools.data.solr; import java.io.IOException; import java.util.Iterator; import java.util.List; import java.util.NoSuchElementException; import java.util.logging.Level; import org.apache.commons.lang.StringUtils; import org.apache.solr.client.solrj.SolrQuery; import org.apache.solr.client.solrj.SolrServerException; import org.apache.solr.client.solrj.impl.HttpSolrServer; import org.apache.solr.client.solrj.response.QueryResponse; import org.apache.solr.common.SolrDocument; import org.apache.solr.common.params.CursorMarkParams; import org.geotools.data.FeatureReader; import org.geotools.feature.simple.SimpleFeatureBuilder; import org.opengis.feature.simple.SimpleFeature; import org.opengis.feature.simple.SimpleFeatureType; import org.opengis.feature.type.AttributeDescriptor; import org.opengis.feature.type.GeometryDescriptor; import com.vividsolutions.jts.geom.Geometry; import com.vividsolutions.jts.io.ParseException; import com.vividsolutions.jts.io.WKTReader; /** * Reader for SOLR datastore */ public class SolrFeatureReader implements FeatureReader<SimpleFeatureType, SimpleFeature> { private Iterator<SolrDocument> solrDocIterator; private SimpleFeatureType featureType; private Boolean next; private SimpleFeatureBuilder builder; private SolrAttribute pkey; private HttpSolrServer server; private WKTReader wktReader; private SolrDataStore solrDataStore; private String cursorMark; private String nextCursorMark; private SolrQuery solrQuery; private long counter; /** * Creates the feature reader for SOLR store <br> * The feature reader use SOLR CURSOR to paginate request, so multiple SOLR query will be * executed * * @param featureType the feature type to query * @param solrUrl the URL of SOLR server * @param solrQuery the SOLR query to execute * @param solrDataStore the SOLR store * @throws SolrServerException */ public SolrFeatureReader(SimpleFeatureType featureType, HttpSolrServer server, SolrQuery solrQuery, SolrDataStore solrDataStore) throws SolrServerException { this.featureType = featureType; this.solrQuery = solrQuery; this.wktReader = new WKTReader(); this.solrDataStore = solrDataStore; this.pkey = solrDataStore.getPrimaryKey(featureType.getTypeName()); this.builder = new SimpleFeatureBuilder(featureType); this.server = server; // Add always pk as field if not already present if (solrQuery.getFields() != null && !solrQuery.getFields().contains(pkey.getName())) { solrQuery.addField(pkey.getName()); } // Can't use pagination with start, then first query for cursor mark of start if (solrQuery.getStart() != null && solrQuery.getStart() > 0) { cursorMark = getCursorMarkForStart(server, solrQuery); } else { cursorMark = CursorMarkParams.CURSOR_MARK_START; } solrQuery.set(CursorMarkParams.CURSOR_MARK_PARAM, cursorMark); QueryResponse rsp = server.query(solrQuery); if (this.solrDataStore.getLogger().isLoggable(Level.FINE)) { this.solrDataStore.getLogger().log(Level.FINE, "SOLR query done: " + solrQuery.toString()); } this.solrDocIterator = rsp.getResults().iterator(); nextCursorMark = rsp.getNextCursorMark(); counter = 0; } /* * Can't use CURSOR MARK with "start" parameter, so get initial SOLR CURSOR MARK to positioning * CURSOR at the row specified by start query parameter */ private String getCursorMarkForStart(HttpSolrServer server, SolrQuery solrQuery) throws SolrServerException { Integer prevRows = solrQuery.getRows(); solrQuery.setRows(solrQuery.getStart()); solrQuery.setStart(0); solrQuery.set(CursorMarkParams.CURSOR_MARK_PARAM, CursorMarkParams.CURSOR_MARK_START); QueryResponse rsp = server.query(solrQuery); if (this.solrDataStore.getLogger().isLoggable(Level.FINE)) { this.solrDataStore.getLogger().log(Level.FINE, "SOLR query done: " + solrQuery.toString()); } String nextC = rsp.getNextCursorMark(); solrQuery.setRows(prevRows); return nextC; } @Override public SimpleFeatureType getFeatureType() { return this.featureType; } /** * SOLR multiValues fields are returned as single String field, with values concatenated and * separated by ";" */ @Override public SimpleFeature next() throws IOException, IllegalArgumentException, NoSuchElementException { String fid = ""; try { if (!hasNext()) { throw new NoSuchElementException("No more features in this reader, you should call " + "hasNext() to check for feature availability"); } SolrDocument doc = this.solrDocIterator.next(); fid = featureType.getTypeName() + "." + doc.getFieldValue(pkey.getName()); final int attributeCount = featureType.getAttributeCount(); for (int i = 0; i < attributeCount; i++) { AttributeDescriptor type = featureType.getDescriptor(i); Object value = doc.getFieldValue(type.getLocalName()); if (value instanceof List<?>) { value = StringUtils.join(((List) value).toArray(), ";"); } if (type instanceof GeometryDescriptor) { GeometryDescriptor gatt = (GeometryDescriptor) type; if (value != null) { Geometry geometry = wktReader.read(value.toString()); if (geometry != null && geometry.getUserData() == null) { geometry.setUserData(gatt.getCoordinateReferenceSystem()); } builder.add(geometry); } } else { builder.add(value); } } return builder.buildFeature(fid); } catch (ParseException e) { throw new RuntimeException(e); } finally { if (this.solrDataStore.getLogger().isLoggable(Level.FINE)) { this.solrDataStore.getLogger().log(Level.FINE, "Created " + fid); } next = null; counter++; } } /** * SOLR CURSOR MARK is used to retrieve data until no more cursor and no more data is available */ @Override public boolean hasNext() { if (next == null) { if (this.solrDocIterator.hasNext()) { next = true; } else { if (counter < solrQuery.getRows() && !cursorMark.equals(nextCursorMark)) { cursorMark = nextCursorMark; solrQuery.set(CursorMarkParams.CURSOR_MARK_PARAM, cursorMark); try { QueryResponse rsp = server.query(solrQuery); if (this.solrDataStore.getLogger().isLoggable(Level.FINE)) { this.solrDataStore.getLogger().log(Level.FINE, solrQuery.toString()); } this.solrDocIterator = rsp.getResults().iterator(); nextCursorMark = rsp.getNextCursorMark(); next = this.solrDocIterator.hasNext(); } catch (SolrServerException e) { this.solrDataStore.getLogger().log(Level.SEVERE, e.getMessage(), e); next = false; } } else { next = false; } } } return next.booleanValue(); } @Override public void close() throws IOException { // nothing to do } }