Java tutorial
/* * Copyright 2013 Hannes Janetzek * * This file is part of the OpenScienceMap project (http://www.opensciencemap.org). * * This program 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, either version 3 of the License, or (at your option) any later version. * * This program 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. * * You should have received a copy of the GNU Lesser General Public License along with * this program. If not, see <http://www.gnu.org/licenses/>. */ package org.oscim.utils.overpass; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLEncoder; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.zip.GZIPInputStream; import java.util.zip.Inflater; import java.util.zip.InflaterInputStream; import org.oscim.core.Tag; import org.oscim.core.TagSet; import org.oscim.core.osm.Bound; import org.oscim.core.osm.OsmData; import org.oscim.core.osm.OsmElement; import org.oscim.core.osm.OsmMember; import org.oscim.core.osm.OsmNode; import org.oscim.core.osm.OsmRelation; import org.oscim.core.osm.OsmWay; import com.fasterxml.jackson.core.JsonFactory; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonToken; public class OverpassAPIReader { private static final String OVERPASS_API = "http://city.informatik.uni-bremen.de/oapi/interpreter"; private static final int RESPONSECODE_OK = 200; /** * The timeout we use for the HttpURLConnection. */ private static final int TIMEOUT = 15000; /** * The base url of the server. Defaults to. * "http://www.openstreetmap.org/api/0.5". */ private final String myBaseUrl = OVERPASS_API; /** * The http connection used to retrieve data. */ private HttpURLConnection myActiveConnection; /** * The stream providing response data. */ private InputStream responseStream; private final String query; /** * Creates a new instance with the specified geographical coordinates. * * @param left * The longitude marking the left edge of the bounding box. * @param right * The longitude marking the right edge of the bounding box. * @param top * The latitude marking the top edge of the bounding box. * @param bottom * The latitude marking the bottom edge of the bounding box. * @param baseUrl * (optional) The base url of the server (eg. * http://www.openstreetmap.org/api/0.5). */ public OverpassAPIReader(final double left, final double right, final double top, final double bottom, final String baseUrl, final String query) { String bbox = "(" + Math.min(top, bottom) + "," + Math.min(left, right) + "," + Math.max(top, bottom) + "," + Math.max(left, right) + ")"; this.query = query.replaceAll("\\{\\{bbox\\}\\}", bbox); } /** * Open a connection to the given url and return a reader on the input * stream from that connection. * * @param pUrlStr * The exact url to connect to. * @return An reader reading the input stream (servers answer) or * <code>null</code>. * @throws IOException * on io-errors */ private InputStream getInputStream(final String pUrlStr) throws IOException { URL url; int responseCode; String encoding; url = new URL(pUrlStr); myActiveConnection = (HttpURLConnection) url.openConnection(); myActiveConnection.setRequestProperty("Accept-Encoding", "gzip, deflate"); responseCode = myActiveConnection.getResponseCode(); if (responseCode != RESPONSECODE_OK) { String message; String apiErrorMessage; apiErrorMessage = myActiveConnection.getHeaderField("Error"); if (apiErrorMessage != null) { message = "Received API HTTP response code " + responseCode + " with message \"" + apiErrorMessage + "\" for URL \"" + pUrlStr + "\"."; } else { message = "Received API HTTP response code " + responseCode + " for URL \"" + pUrlStr + "\"."; } throw new IOException(message); } myActiveConnection.setConnectTimeout(TIMEOUT); encoding = myActiveConnection.getContentEncoding(); responseStream = myActiveConnection.getInputStream(); if (encoding != null && encoding.equalsIgnoreCase("gzip")) { responseStream = new GZIPInputStream(responseStream); } else if (encoding != null && encoding.equalsIgnoreCase("deflate")) { responseStream = new InflaterInputStream(responseStream, new Inflater(true)); } return responseStream; } class TmpRelation { Long id; String type; String role; } private final List<Bound> bounds = new ArrayList<Bound>(); private Map<Long, OsmNode> nodesById = new HashMap<Long, OsmNode>(); private Map<Long, OsmWay> waysById = new HashMap<Long, OsmWay>(); private Map<Long, OsmRelation> relationsById = new HashMap<Long, OsmRelation>(); private Map<OsmRelation, List<TmpRelation>> relationMembersForRelation = new HashMap<OsmRelation, List<TmpRelation>>(); private final Collection<OsmNode> ownNodes = new ArrayList<OsmNode>(10000); private final Collection<OsmWay> ownWays = new ArrayList<OsmWay>(1000); private final Collection<OsmRelation> ownRelations = new ArrayList<OsmRelation>(100); public void parse(InputStream in) throws IOException { JsonFactory jsonFactory = new JsonFactory(); try { JsonParser jp = jsonFactory.createJsonParser(in); JsonToken t; while ((t = jp.nextToken()) != null) { if (t == JsonToken.START_OBJECT) { jp.nextToken(); String name = jp.getCurrentName(); jp.nextToken(); if ("type".equals(name)) { String type = jp.getText(); if ("node".equals(type)) parseNode(jp); else if ("way".equals(type)) parseWay(jp); else if ("relation".equals(type)) parseRelation(jp); } } } } catch (JsonParseException e) { e.printStackTrace(); } } private void parseNode(JsonParser jp) throws JsonParseException, IOException { long id = 0; double lat = 0, lon = 0; TagSet tags = null; while (jp.nextToken() != JsonToken.END_OBJECT) { String name = jp.getCurrentName(); jp.nextToken(); if ("id".equals(name)) id = jp.getLongValue(); else if ("lat".equals(name)) lat = jp.getDoubleValue(); else if ("lon".equals(name)) lon = jp.getDoubleValue(); else if ("tags".equals(name)) tags = parseTags(jp); } // log("node: "+id + " "+ lat + " " + lon); OsmNode node = new OsmNode(lat, lon, tags, id); ownNodes.add(node); nodesById.put(Long.valueOf(id), node); } private void parseWay(JsonParser jp) throws JsonParseException, IOException { long id = 0; TagSet tags = null; ArrayList<OsmNode> wayNodes = new ArrayList<OsmNode>(); while (jp.nextToken() != JsonToken.END_OBJECT) { String name = jp.getCurrentName(); jp.nextToken(); if ("id".equals(name)) id = jp.getLongValue(); else if ("nodes".equals(name)) { while (jp.nextToken() != JsonToken.END_ARRAY) { Long nodeId = Long.valueOf(jp.getLongValue()); OsmNode node = nodesById.get(nodeId); if (node != null) // log("missing node " + nodeId); // else wayNodes.add(node); } } else if ("tags".equals(name)) tags = parseTags(jp); } // log("way: "+ id + " " + wayNodes.size()); OsmWay way = new OsmWay(tags, id, wayNodes); ownWays.add(way); waysById.put(Long.valueOf(id), way); } private void parseRelation(JsonParser jp) throws JsonParseException, IOException { long id = 0; TagSet tags = null; ArrayList<TmpRelation> members = new ArrayList<TmpRelation>(); while (jp.nextToken() != JsonToken.END_OBJECT) { String name = jp.getCurrentName(); jp.nextToken(); if ("id".equals(name)) id = jp.getLongValue(); else if ("members".equals(name)) { while (jp.nextToken() != JsonToken.END_ARRAY) { TmpRelation member = new TmpRelation(); while (jp.nextToken() != JsonToken.END_OBJECT) { name = jp.getCurrentName(); jp.nextToken(); if ("type".equals(name)) member.type = jp.getText(); else if ("ref".equals(name)) member.id = Long.valueOf(jp.getLongValue()); else if ("role".equals(name)) member.role = jp.getText(); } members.add(member); } } else if ("tags".equals(name)) tags = parseTags(jp); } OsmRelation relation = new OsmRelation(tags, id, members.size()); ownRelations.add(relation); relationsById.put(Long.valueOf(id), relation); relationMembersForRelation.put(relation, members); } private static TagSet parseTags(JsonParser jp) throws JsonParseException, IOException { TagSet tags = null; while (jp.nextToken() != JsonToken.END_OBJECT) { String key = jp.getCurrentName(); jp.nextToken(); String val = jp.getText(); if (tags == null) tags = new TagSet(4); tags.add(new Tag(key, val, false)); } return tags; } private static void log(String msg) { System.out.println(msg); } public OsmData getData() { String encoded; try { encoded = URLEncoder.encode(this.query, "utf-8"); } catch (UnsupportedEncodingException e1) { e1.printStackTrace(); return null; } System.out.println(myBaseUrl + "?data=" + encoded); InputStream inputStream = null; try { inputStream = getInputStream(myBaseUrl + "?data=[out:json];" + encoded); parse(inputStream); } catch (IOException e) { e.printStackTrace(); } finally { if (inputStream != null) try { inputStream.close(); } catch (IOException e) { //... } inputStream = null; } for (Entry<OsmRelation, List<TmpRelation>> entry : relationMembersForRelation.entrySet()) { OsmRelation relation = entry.getKey(); for (TmpRelation member : entry.getValue()) { OsmElement memberObject = null; if ("node".equals(member)) { memberObject = nodesById.get(member.id); } else if ("way".equals(member)) { memberObject = waysById.get(member.id); } else if ("relation".equals(member)) { memberObject = relationsById.get(member.id); } else { // log("missing relation " + member.id); continue; } if (memberObject != null) { OsmMember ownMember = new OsmMember(member.role, memberObject); relation.relationMembers.add(ownMember); } } } log("nodes: " + ownNodes.size() + " ways: " + ownWays.size() + " relations: " + ownRelations.size()); // give up references to original collections nodesById = null; waysById = null; relationsById = null; relationMembersForRelation = null; return new OsmData(bounds, ownNodes, ownWays, ownRelations); } }