Java tutorial
/* * GeoTools - The Open Source Java GIS Toolkit * http://geotools.org * * (C) 2002-2011, 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.sfs; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.ProtocolException; import java.net.URL; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import java.util.logging.Level; import java.util.logging.Logger; import java.util.zip.GZIPInputStream; import org.apache.commons.codec.binary.Base64; import org.geotools.data.store.ContentDataStore; import org.geotools.data.store.ContentEntry; import org.geotools.data.store.ContentFeatureSource; import org.geotools.feature.NameImpl; import org.geotools.filter.FilterCapabilities; import org.json.simple.JSONArray; import org.json.simple.parser.JSONParser; import org.opengis.feature.type.Name; import org.opengis.filter.And; import org.opengis.filter.ExcludeFilter; import org.opengis.filter.IncludeFilter; import org.opengis.filter.PropertyIsLike; import org.opengis.filter.spatial.BBOX; import org.opengis.filter.spatial.Intersects; import org.opengis.referencing.crs.CoordinateReferenceSystem; import com.vividsolutions.jts.geom.Envelope; /** * This DataStore is based on OpenDataStore protocol using GeoJSON as the * encoding format loosely based on RESTFUL principles. This code expanded on * from GeoREST in Unsupported Modules. * @author * * * * @source $URL$ */ public class SFSDataStore extends ContentDataStore { /** * The store filter capabilities * @return The filter capabilities, never <code>null</code>. */ static FilterCapabilities ODS_FILTER_CAPABILITIES = new FilterCapabilities() { { addAll(FilterCapabilities.SIMPLE_COMPARISONS_OPENGIS); addType(And.class); // TODO: check these two filters are actually supported in the encoder addType(BBOX.class); addType(Intersects.class); addType(IncludeFilter.class); addType(ExcludeFilter.class); addType(PropertyIsLike.class); } }; protected static final Logger LOGGER = org.geotools.util.logging.Logging .getLogger("org.geotools.data.simplefeatureservice"); String baseURL; Map<Name, SFSLayer> layers = new LinkedHashMap<Name, SFSLayer>(); String user; String password; int timeout; /** * Constructor -- it takes in the base URl and then appends "/capabilities" * to pull the list of available layers * @param URL * */ public SFSDataStore(URL fnURL, String namespaceURI) throws IOException { String strURL = fnURL.toString(); this.baseURL = strURL + (strURL.endsWith("/") ? "" : "/"); if (baseURL.endsWith("capabilities/")) { baseURL = baseURL.substring(0, baseURL.length() - "capabilities/".length()); } this.namespaceURI = namespaceURI; processCapabilities(); } /** * Constructor -- it takes in the base URl and then appends "/capabilities" * to pull the list of available layers * @param URL * */ public SFSDataStore(URL fnURL, String namespaceURI, String user, String password, int timeout) throws IOException { String strURL = fnURL.toString(); this.baseURL = strURL + (strURL.endsWith("/") ? "" : "/"); if (baseURL.endsWith("capabilities/")) { baseURL = baseURL.substring(0, baseURL.length() - "capabilities/".length()); } this.namespaceURI = namespaceURI; this.user = user; this.password = password; this.timeout = timeout; processCapabilities(); } /** * Constructor -- it simply uses the json response from the server to extract * the layer information. Only used for testing, not exposing it to the whole world * @param String * */ SFSDataStore(String json, String namespaceURI) throws IOException { this.namespaceURI = namespaceURI; processCapabilities(json); } /** * It processes the incoming URL and gets the response in the form of stream. * It then converts the stream into a string(it should be in json format) * @param * */ public final void processCapabilities() throws IOException { processCapabilities(resourceToString("capabilities", null)); } /** * This method processes the JSON from the server and extracts layer names * and populates typeNames * @param capabilitiesJSON * */ final void processCapabilities(String capabilitiesJSON) throws IOException { JSONParser parser = new JSONParser(); try { Object obj = parser.parse(capabilitiesJSON); JSONArray array = (JSONArray) obj; Iterator itr = array.iterator(); while (itr.hasNext()) { Map tmpMap = (HashMap) itr.next(); String strName = ((String) tmpMap.get("name")).trim(); Name name = new NameImpl(namespaceURI, strName); boolean xyOrder = (!tmpMap.containsKey("axisorder")) ? true : (tmpMap.get("axisorder").equals("xy")); String strCRS = null; CoordinateReferenceSystem crs = null; if (tmpMap.containsKey("crs")) { strCRS = ((String) tmpMap.get("crs")).trim(); crs = SFSDataStoreUtil.decodeXY(strCRS); } Envelope envelope = null; if (tmpMap.containsKey("bbox")) { JSONArray boundingArray = (JSONArray) tmpMap.get("bbox"); if (!xyOrder) { SFSDataStoreUtil.flipYXInsideTheBoundingBox(boundingArray); } envelope = new Envelope(((Number) boundingArray.get(0)).doubleValue(), ((Number) boundingArray.get(2)).doubleValue(), ((Number) boundingArray.get(1)).doubleValue(), ((Number) boundingArray.get(3)).doubleValue()); } SFSLayer layer = new SFSLayer(name, xyOrder, strCRS, crs, envelope); layers.put(name, layer); } } catch (Exception e) { LOGGER.log(Level.SEVERE, "Exception occurred while parsing the capabilities", e); throw (IOException) new IOException().initCause(e); } } /** * Return the Layer Names * @param * @return typeNames * @throws IOException * */ public List<Name> createTypeNames() throws IOException { return new ArrayList<Name>(layers.keySet()); } /** * Call FeatureSource * @param ContentEntry * @return ContentFeatureSource * @throws IOException * */ protected ContentFeatureSource createFeatureSource(ContentEntry entry) throws IOException { return new SFSFeatureSource(entry); } /** * Returns the layer definition for the given name * @param name * @return */ SFSLayer getLayer(Name name) { return layers.get(name); } /** * This method requests the response from the URL either through GET/POST * and then converts the response to string and returns the string * fnData is URL encoded string * The request is going to be a POST one if postData is not null, a GET otherwise * @param is * @return String * @throws IOException */ String resourceToString(String resource, String postData) throws IOException { InputStream is = resourceToStream(resource, postData); if (is != null) { StringBuilder sb = new StringBuilder(); String line; try { BufferedReader reader = new BufferedReader( new InputStreamReader(is, SFSDataStoreUtil.DEFAULT_ENCODING)); while ((line = reader.readLine()) != null) { sb.append(line); } } finally { is.close(); } return sb.toString(); } return ""; } /** * This method requests the response from the URL either through GET/POST * and returns the response as a stream * The request is going to be a POST one if postData is not null, a GET otherwise * @param is * @return String * @throws IOException */ InputStream resourceToStream(String resource, String postData) throws MalformedURLException, IOException, ProtocolException { boolean doPost = false; URL url; if (postData != null && (baseURL.length() + resource.length() + postData.length() < 2048)) { url = new URL(baseURL + resource + "?" + postData); } else { url = new URL(baseURL + resource); } // TODO: use commons http client + persistent connections instead HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setRequestProperty("Accept-Encoding", "gzip"); // if we have username/password use them to setup basic auth if (user != null && password != null) { String combined = nullToEmpty(user) + ":" + nullToEmpty(password); byte[] authBytes = combined.getBytes("US-ASCII"); String encoded = new String(Base64.encodeBase64(authBytes)); urlConnection.setRequestProperty("Authorization", "Basic " + encoded); } // enforce the timeout if we have one if (timeout > 0) { urlConnection.setConnectTimeout(timeout); urlConnection.setReadTimeout(timeout); } urlConnection.setDoInput(true); if (doPost && postData != null && !"".equals(postData.trim())) { urlConnection.setRequestMethod("POST"); urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); urlConnection.setDoOutput(true); /*write the data to server*/ OutputStreamWriter wr = null; try { wr = new OutputStreamWriter(urlConnection.getOutputStream()); wr.write(postData); wr.flush(); } finally { if (wr != null) { wr.close(); } } } else { urlConnection.setRequestMethod("GET"); } /* Get the response from the server*/ if (urlConnection.getResponseCode() != 200) { throw new IOException("Server reported and error with code " + urlConnection.getResponseCode() + ": " + urlConnection.getResponseMessage() + " accessing resource " + url.toExternalForm()); } else { InputStream is = urlConnection.getInputStream(); String encoding = urlConnection.getContentEncoding(); if ("gzip".equalsIgnoreCase(encoding)) { is = new GZIPInputStream(is); } return is; } } private String nullToEmpty(String string) { return string != null ? string : ""; } }