Java tutorial
/* Copyright 2014 Fabian Steeg, hbz. Licensed under the Eclipse Public License 1.0 */ package controllers.oer; import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.io.InputStream; import java.io.StringWriter; import java.net.MalformedURLException; import java.net.URL; import java.nio.file.FileVisitResult; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.SimpleFileVisitor; import java.nio.file.attribute.BasicFileAttributes; import java.util.Arrays; import java.util.HashMap; import java.util.Map; import java.util.Map.Entry; import java.util.Scanner; import org.apache.jena.riot.Lang; import org.apache.jena.riot.RDFDataMgr; import org.elasticsearch.ElasticsearchException; import org.elasticsearch.action.index.IndexRequestBuilder; import org.elasticsearch.action.index.IndexResponse; import org.elasticsearch.client.IndicesAdminClient; import play.Play; import play.libs.Json; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.node.ArrayNode; import com.github.jsonldjava.core.JsonLdError; import com.github.jsonldjava.core.JsonLdOptions; import com.github.jsonldjava.core.JsonLdProcessor; import com.github.jsonldjava.utils.JSONUtils; import com.google.common.base.Charsets; import com.google.common.io.CharStreams; import com.hp.hpl.jena.rdf.model.Model; import com.hp.hpl.jena.rdf.model.ModelFactory; /** * Convert N-Triples to JSON-LD and index it in Elasticsearch. * * @author Fabian Steeg (fsteeg) */ public class NtToEs { static final String CONFIG = "public/data/index-config.json"; static final String CONTEXT = "public/data/context.json"; static final String TYPE = Application.DATA_TYPE; static final String INDEX = Application.DATA_INDEX; static final Map<String, String> idMap = new HashMap<String, String>(); public static void main(String... args) throws ElasticsearchException, FileNotFoundException, IOException { if (args.length != 1 && args.length != 2) { System.out.println("Pass the root directory to crawl. " + "Will recursively gather all content from *.nt " + "files with identical names, convert these to " + "compact JSON-LD and index it in ES. " + "If a second argument is passed it is processed " + "as a TSV file that maps file names (w/o " + "extensions) to IDs to be used for ES. Else the " + "file names (w/o extensions) are used."); args = new String[] { "../oer-data/tmp", "../oer-data/src/main/resources/internalId2uuid.tsv" }; System.out.println("Using defaults: " + Arrays.asList(args)); } if (args.length == 2) initMap(args[1]); TripleCrawler crawler = new TripleCrawler(); Files.walkFileTree(Paths.get(args[0]), crawler); createIndex(config(), INDEX); process(crawler.data); } static String config() throws IOException, FileNotFoundException { return CharStreams.toString(new FileReader(CONFIG)); } private static final class TripleCrawler extends SimpleFileVisitor<Path> { Map<String, StringBuilder> data = new HashMap<String, StringBuilder>(); @Override public FileVisitResult visitFile(Path path, BasicFileAttributes attr) throws IOException { if (path.toString().endsWith(".nt")) { String content = com.google.common.io.Files.toString(path.toFile(), Charsets.UTF_8); String key = path.getFileName().toString(); collectContent(uuidForFileName(key), content); } return FileVisitResult.CONTINUE; } private void collectContent(String name, String content) { if (!data.containsKey(name)) data.put(name, new StringBuilder()); data.get(name).append("\n").append(content); } } static void createIndex(String config, String index) { IndicesAdminClient admin = Application.client.admin().indices(); if (!admin.prepareExists(index).execute().actionGet().isExists()) { System.err.println("Creating index with config:\n" + config); admin.prepareCreate(index).setSource(config).execute().actionGet(); } } private static void process(Map<String, StringBuilder> map) { for (Entry<String, StringBuilder> e : map.entrySet()) { String mapKey = e.getKey(); try { String jsonLd = rdfToJsonLd(e.getValue().toString(), Lang.NTRIPLES); String parent = findParent(jsonLd); String key = uuidForFileName(mapKey); indexData(key, jsonLd, INDEX, TYPE, parent); } catch (Exception x) { System.err.printf("Could not process file %s due to %s\n", mapKey, x.getMessage()); x.printStackTrace(); } } } private static String uuidForFileName(String fileName) { String id = fileName.split("\\.")[0]; return idMap.isEmpty() || idMap.get(id) == null ? id : idMap.get(id); } static String findParent(String jsonLd) { JsonNode value = Json.parse(jsonLd).findValue("addressCountry"); return value != null && value.isArray() /* else in context */ ? value.get(0).asText().trim() : "http://sws.geonames.org/"; } private static void initMap(String mapFile) { try (Scanner s = new Scanner(new File(mapFile))) { while (s.hasNextLine()) { String[] keyVal = s.nextLine().split("\\s"); idMap.put(keyVal[0].trim(), keyVal[1].trim()); } } catch (FileNotFoundException e) { e.printStackTrace(); } } static void indexData(String id, String data, String index, String type, String parent) { IndexRequestBuilder builder = Application.client.prepareIndex(index, type, id).setSource(data); if (parent != null) builder = builder.setParent(parent); IndexResponse r = builder.execute().actionGet(); System.out.printf("Indexed into index %s, type %s, id %s, version %s: %s\n", r.getIndex(), r.getType(), r.getId(), r.getVersion(), data); } static String rdfToJsonLd(String data, Lang lang) { StringWriter stringWriter = new StringWriter(); InputStream in = new ByteArrayInputStream(data.getBytes(Charsets.UTF_8)); Model model = ModelFactory.createDefaultModel(); RDFDataMgr.read(model, in, lang); RDFDataMgr.write(stringWriter, model, Lang.JSONLD); return compact(stringWriter.toString()); } static String jsonLdToRdf(JsonNode data, Lang lang) { StringWriter stringWriter = new StringWriter(); Model model = ModelFactory.createDefaultModel(); for (JsonNode jsonNode : data) { InputStream in = new ByteArrayInputStream(jsonNode.toString().getBytes(Charsets.UTF_8)); RDFDataMgr.read(model, in, Lang.JSONLD); } RDFDataMgr.write(stringWriter, model, lang); return stringWriter.toString(); } static String compact(String json) { try { Object contextJson = JSONUtils.fromURL(context()); JsonLdOptions options = new JsonLdOptions(); options.setCompactArrays(false); // ES needs consistent data Map<String, Object> compact = JsonLdProcessor.compact(JSONUtils.fromString(json), contextJson, options); return withGeo(compact); } catch (IOException | JsonLdError e) { throw new IllegalStateException("Could not compact JSON-LD: \n" + json, e); } } private static String withGeo(Map<String, Object> compact) { JsonNode json = Json.parse(JSONUtils.toString(compact)); JsonNode lat = json.findValue("latitude"); JsonNode lon = json.findValue("longitude"); if (lat != null && lon != null && lat instanceof ArrayNode && lon instanceof ArrayNode) compact.put("location", ((ArrayNode) lat).get(0).textValue() + ", " + ((ArrayNode) lon).get(0).textValue()); System.out.println(JSONUtils.toPrettyString(compact)); return JSONUtils.toString(compact); } public static URL context() throws MalformedURLException { final String path = "public/data"; final String file = "context.json"; if (new File(path, file).exists()) return new File(path, file).toURI().toURL(); return Play.application().resource("/" + path + "/" + file); } }