Java tutorial
/* * Copyright 2014 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.tiling.source.geojson; import static com.fasterxml.jackson.core.JsonToken.END_ARRAY; import static com.fasterxml.jackson.core.JsonToken.END_OBJECT; import static com.fasterxml.jackson.core.JsonToken.FIELD_NAME; import static com.fasterxml.jackson.core.JsonToken.START_ARRAY; import static com.fasterxml.jackson.core.JsonToken.START_OBJECT; import static com.fasterxml.jackson.core.JsonToken.VALUE_NUMBER_FLOAT; import static com.fasterxml.jackson.core.JsonToken.VALUE_NUMBER_INT; import static com.fasterxml.jackson.core.JsonToken.VALUE_STRING; import static org.oscim.core.MercatorProjection.latitudeToY; import static org.oscim.core.MercatorProjection.longitudeToX; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.LinkedHashMap; import org.oscim.core.GeometryBuffer.GeometryType; import org.oscim.core.MapElement; import org.oscim.core.Tile; import org.oscim.tiling.ITileDataSink; import org.oscim.tiling.source.ITileDecoder; import org.oscim.utils.ArrayUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; 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 GeoJsonTileDecoder implements ITileDecoder { static final Logger log = LoggerFactory.getLogger(GeoJsonTileDecoder.class); private final MapElement mMapElement; private final GeoJsonTileSource mTileSource; private final LinkedHashMap<String, Object> mTagMap; private final JsonFactory mJsonFactory; private final static char[] FIELD_FEATURES = "features".toCharArray(); private final static char[] FIELD_GEOMETRY = "geometry".toCharArray(); private final static char[] FIELD_PROPERTIES = "properties".toCharArray(); private final static char[] FIELD_COORDINATES = "coordinates".toCharArray(); private final static char[] FIELD_TYPE = "type".toCharArray(); private final static char[] LINETRING = "LineString".toCharArray(); private final static char[] POLYGON = "Polygon".toCharArray(); private final static char[] POINT = "Point".toCharArray(); private final static char[] MULTI_LINESTRING = "MultiLineString".toCharArray(); private final static char[] MULTI_POLYGON = "MultiPolygon".toCharArray(); private final static char[] MULTI_POINT = "MultiPoint".toCharArray(); private ITileDataSink mTileDataSink; private double mTileY, mTileX, mTileScale; public GeoJsonTileDecoder(GeoJsonTileSource tileSource) { mTileSource = tileSource; mTagMap = new LinkedHashMap<String, Object>(); mJsonFactory = new JsonFactory(); mMapElement = new MapElement(); mMapElement.layer = 5; } @Override public boolean decode(Tile tile, ITileDataSink sink, InputStream is) throws IOException { mTileDataSink = sink; mTileScale = 1 << tile.zoomLevel; mTileX = tile.tileX / mTileScale; mTileY = tile.tileY / mTileScale; mTileScale *= Tile.SIZE; JsonParser jp = mJsonFactory.createParser(new InputStreamReader(is)); for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == FIELD_NAME) { if (match(jp, FIELD_FEATURES)) { if (jp.nextToken() != START_ARRAY) continue; while ((t = jp.nextToken()) != null) { if (t == START_OBJECT) parseFeature(jp); if (t == END_ARRAY) break; } } } } return true; } private void parseFeature(JsonParser jp) throws JsonParseException, IOException { mMapElement.clear(); mMapElement.tags.clear(); mTagMap.clear(); for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == FIELD_NAME) { if (match(jp, FIELD_GEOMETRY)) { if (jp.nextToken() == START_OBJECT) parseGeometry(jp); } if (match(jp, FIELD_PROPERTIES)) { if (jp.nextToken() == START_OBJECT) parseProperties(jp); } continue; } if (t == END_OBJECT) break; } //add tag information mTileSource.decodeTags(mMapElement, mTagMap); if (mMapElement.tags.numTags == 0) return; mTileSource.postGeomHook(mMapElement); if (mMapElement.type == GeometryType.NONE) return; //process this element mTileDataSink.process(mMapElement); } private void parseProperties(JsonParser jp) throws JsonParseException, IOException { for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == FIELD_NAME) { String text = jp.getCurrentName(); t = jp.nextToken(); if (t == VALUE_STRING) { mTagMap.put(text, jp.getText()); } else if (t == VALUE_NUMBER_INT) { mTagMap.put(text, jp.getNumberValue()); } continue; } if (t == END_OBJECT) break; } } private void parseGeometry(JsonParser jp) throws JsonParseException, IOException { boolean multi = false; GeometryType type = GeometryType.NONE; for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == FIELD_NAME) { if (match(jp, FIELD_COORDINATES)) { if (jp.nextToken() != START_ARRAY) continue; if (multi) { parseMulti(jp, type); } else { if (type == GeometryType.POLY) parsePolygon(jp); if (type == GeometryType.LINE) parseLineString(jp); if (type == GeometryType.POINT) parseCoordinate(jp); } } else if (match(jp, FIELD_TYPE)) { multi = false; jp.nextToken(); if (match(jp, LINETRING)) type = GeometryType.LINE; else if (match(jp, POLYGON)) type = GeometryType.POLY; else if (match(jp, POINT)) type = GeometryType.POINT; else if (match(jp, MULTI_LINESTRING)) { type = GeometryType.LINE; multi = true; } else if (match(jp, MULTI_POLYGON)) { type = GeometryType.POLY; multi = true; } else if (match(jp, MULTI_POINT)) { type = GeometryType.POINT; multi = true; } if (type == GeometryType.POINT) mMapElement.startPoints(); } continue; } if (t == END_OBJECT) break; } } private void parseMulti(JsonParser jp, GeometryType type) throws JsonParseException, IOException { for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == END_ARRAY) break; if (t == START_ARRAY) { if (type == GeometryType.POLY) parsePolygon(jp); else if (type == GeometryType.LINE) parseLineString(jp); else if (type == GeometryType.POINT) parseCoordinate(jp); ; } else { //.... } } } private void parsePolygon(JsonParser jp) throws JsonParseException, IOException { int ring = 0; for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == START_ARRAY) { if (ring == 0) mMapElement.startPolygon(); else mMapElement.startHole(); ring++; parseCoordSequence(jp); removeLastPoint(); continue; } if (t == END_ARRAY) break; } } private void removeLastPoint() { mMapElement.pointPos -= 2; mMapElement.index[mMapElement.indexPos] -= 2; } private void parseLineString(JsonParser jp) throws JsonParseException, IOException { mMapElement.startLine(); parseCoordSequence(jp); } private void parseCoordSequence(JsonParser jp) throws JsonParseException, IOException { for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == START_ARRAY) { parseCoordinate(jp); continue; } if (t == END_ARRAY) break; } } private void parseCoordinate(JsonParser jp) throws JsonParseException, IOException { int pos = 0; double x = 0, y = 0; //, z = 0; for (JsonToken t; (t = jp.nextToken()) != null;) { if (t == VALUE_NUMBER_FLOAT || t == VALUE_NUMBER_INT) { // avoid String allocation (by getDouble...) char[] val = jp.getTextCharacters(); int offset = jp.getTextOffset(); int length = jp.getTextLength(); double c = ArrayUtils.parseNumber(val, offset, offset + length); if (pos == 0) x = c; if (pos == 1) y = c; //if (pos == 2) //z = c; pos++; continue; } if (t == END_ARRAY) break; } mMapElement.addPoint((float) ((longitudeToX(x) - mTileX) * mTileScale), (float) ((latitudeToY(y) - mTileY) * mTileScale)); } private final static boolean match(JsonParser jp, char[] fieldName) throws JsonParseException, IOException { int length = jp.getTextLength(); if (length != fieldName.length) return false; char[] val = jp.getTextCharacters(); int offset = jp.getTextOffset(); for (int i = 0; i < length; i++) { if (fieldName[i] != val[i + offset]) return false; } return true; } }