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Merge pull request #225 from GoogleCloudPlatform/ds-geo
Add AE Datastore geo query sample.
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‎appengine/datastore/geo/pom.xml

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<!--
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Copyright 2016 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<project>
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<modelVersion>4.0.0</modelVersion>
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<packaging>war</packaging>
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<version>1.0-SNAPSHOT</version>
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<groupId>com.example.appengine</groupId>
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<artifactId>appengine-datastore-geo</artifactId>
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<parent>
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<groupId>com.google.cloud</groupId>
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<artifactId>doc-samples</artifactId>
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<version>1.0.0</version>
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<relativePath>../../..</relativePath>
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</parent>
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<dependencies>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-api-1.0-sdk</artifactId>
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<version>${appengine.sdk.version}</version>
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</dependency>
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<dependency>
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<groupId>javax.servlet</groupId>
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<artifactId>servlet-api</artifactId>
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<type>jar</type>
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<scope>provided</scope>
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</dependency>
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<!-- Test Dependencies -->
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.10</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>org.mockito</groupId>
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<artifactId>mockito-all</artifactId>
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<version>1.10.19</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-testing</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-api-stubs</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-tools-sdk</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.truth</groupId>
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<artifactId>truth</artifactId>
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<version>0.28</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<!-- for hot reload of the web application -->
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<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
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<plugins>
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<!-- Parent POM defines ${appengine.sdk.version} (updates frequently). -->
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<plugin>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-maven-plugin</artifactId>
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<version>${appengine.sdk.version}</version>
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</plugin>
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</plugins>
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</build>
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</project>

‎appengine/datastore/geo/src/main/java/com/example/appengine/GeoServlet.java

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/*
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.appengine;
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import com.google.appengine.api.datastore.DatastoreService;
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import com.google.appengine.api.datastore.DatastoreServiceFactory;
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import com.google.appengine.api.datastore.Entity;
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import com.google.appengine.api.datastore.FetchOptions;
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import com.google.appengine.api.datastore.GeoPt;
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import com.google.appengine.api.datastore.Query;
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import com.google.appengine.api.datastore.Query.CompositeFilterOperator;
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import com.google.appengine.api.datastore.Query.Filter;
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import com.google.appengine.api.datastore.Query.FilterOperator;
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import com.google.appengine.api.datastore.Query.FilterPredicate;
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import com.google.appengine.api.datastore.Query.GeoRegion.Circle;
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import com.google.appengine.api.datastore.Query.GeoRegion.Rectangle;
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import com.google.appengine.api.datastore.Query.StContainsFilter;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.List;
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import javax.servlet.ServletException;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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/**
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* A servlet to demonstrate the use of Cloud Datastore geospatial queries.
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*/
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public class GeoServlet extends HttpServlet {
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static final String BRAND_PROPERTY = "brand";
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static final String LOCATION_PROPERTY = "location";
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static final String BRAND_PARAMETER = "brand";
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static final String LATITUDE_PARAMETER = "lat";
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static final String LONGITUDE_PARAMETER = "lon";
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static final String RADIUS_PARAMETER = "r";
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static final String BRAND_DEFAULT = "Ocean Ave Shell";
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static final String LATITUDE_DEFAULT = "37.7895873";
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static final String LONGITUDE_DEFAULT = "-122.3917317";
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static final String RADIUS_DEFAULT = "1000.0";
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// Number of meters (approximately) in 1 degree of latitude.
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// http://gis.stackexchange.com/a/2964
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private static final double DEGREE_METERS = 111111.0;
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private final DatastoreService datastore;
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public GeoServlet() {
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datastore = DatastoreServiceFactory.getDatastoreService();
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}
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private static String getParameterOrDefault(
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HttpServletRequest req, String parameter, String defaultValue) {
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String value = req.getParameter(parameter);
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if (value == null || value.isEmpty()) {
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value = defaultValue;
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}
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return value;
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}
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private static GeoPt getOffsetPoint(
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GeoPt original, double latOffsetMeters, double lonOffsetMeters) {
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// Approximate the number of degrees to offset by meters.
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// http://gis.stackexchange.com/a/2964
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// How long (approximately) is one degree of longitude?
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double lonDegreeMeters = DEGREE_METERS * Math.cos(original.getLatitude());
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return new GeoPt(
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(float) (original.getLatitude() + latOffsetMeters / DEGREE_METERS),
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// This may cause errors if given points near the north or south pole.
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(float) (original.getLongitude() + lonOffsetMeters / lonDegreeMeters));
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}
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@Override
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public void doGet(HttpServletRequest req, HttpServletResponse resp)
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throws IOException, ServletException {
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resp.setContentType("text/plain");
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resp.setCharacterEncoding("UTF-8");
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PrintWriter out = resp.getWriter();
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String brand = getParameterOrDefault(req, BRAND_PARAMETER, BRAND_DEFAULT);
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String latStr = getParameterOrDefault(req, LATITUDE_PARAMETER, LATITUDE_DEFAULT);
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String lonStr = getParameterOrDefault(req, LONGITUDE_PARAMETER, LONGITUDE_DEFAULT);
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String radiusStr = getParameterOrDefault(req, RADIUS_PARAMETER, RADIUS_DEFAULT);
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float latitude;
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float longitude;
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double r;
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try {
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latitude = Float.parseFloat(latStr);
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longitude = Float.parseFloat(lonStr);
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r = Double.parseDouble(radiusStr);
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} catch (IllegalArgumentException e) {
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resp.sendError(
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HttpServletResponse.SC_BAD_REQUEST, String.format("Got bad value: %s", e.getMessage()));
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return;
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}
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// Get lat/lon for rectangle.
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GeoPt c = new GeoPt(latitude, longitude);
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GeoPt ne = getOffsetPoint(c, r, r);
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float neLat = ne.getLatitude();
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float neLon = ne.getLongitude();
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GeoPt sw = getOffsetPoint(c, -1 * r, -1 * r);
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float swLat = sw.getLatitude();
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float swLon = sw.getLongitude();
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// [START geospatial_stcontainsfilter_examples]
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// Testing for containment within a circle
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GeoPt center = new GeoPt(latitude, longitude);
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double radius = r; // Value is in meters.
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Filter f1 = new StContainsFilter("location", new Circle(center, radius));
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Query q1 = new Query("GasStation").setFilter(f1);
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// Testing for containment within a rectangle
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GeoPt southwest = new GeoPt(swLat, swLon);
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GeoPt northeast = new GeoPt(neLat, neLon);
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Filter f2 = new StContainsFilter("location", new Rectangle(southwest, northeast));
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Query q2 = new Query("GasStation").setFilter(f2);
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// [END geospatial_stcontainsfilter_examples]
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List<Entity> circleResults = datastore.prepare(q1).asList(FetchOptions.Builder.withDefaults());
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out.printf("Got %d stations in %f meter radius circle.\n", circleResults.size(), radius);
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printStations(out, circleResults);
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out.println();
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List<Entity> rectResults = datastore.prepare(q2).asList(FetchOptions.Builder.withDefaults());
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out.printf("Got %d stations in rectangle.\n", rectResults.size());
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printStations(out, rectResults);
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out.println();
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List<Entity> brandResults = getStationsWithBrand(center, radius, brand);
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out.printf("Got %d stations in circle with brand %s.\n", brandResults.size(), brand);
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printStations(out, brandResults);
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out.println();
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}
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private void printStations(PrintWriter out, List<Entity> stations) {
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for (Entity station : stations) {
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GeoPt location = (GeoPt) station.getProperty(LOCATION_PROPERTY);
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out.printf(
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"%s: @%f, %f\n",
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(String) station.getProperty(BRAND_PROPERTY),
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location.getLatitude(),
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location.getLongitude());
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}
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}
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private List<Entity> getStationsWithBrand(GeoPt center, double radius, String value) {
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// [START geospatial_containment_and_equality_combination]
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Filter f =
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CompositeFilterOperator.and(
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new StContainsFilter("location", new Circle(center, radius)),
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new FilterPredicate("brand", FilterOperator.EQUAL, value));
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// [END geospatial_containment_and_equality_combination]
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Query q = new Query("GasStation").setFilter(f);
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return datastore.prepare(q).asList(FetchOptions.Builder.withDefaults());
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}
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}

‎appengine/datastore/geo/src/main/java/com/example/appengine/StartupServlet.java

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/*
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.appengine;
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import com.google.appengine.api.datastore.DatastoreService;
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import com.google.appengine.api.datastore.DatastoreServiceFactory;
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import com.google.appengine.api.datastore.Entity;
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import com.google.appengine.api.datastore.EntityNotFoundException;
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import com.google.appengine.api.datastore.GeoPt;
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import com.google.appengine.api.datastore.Key;
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import com.google.appengine.api.datastore.KeyFactory;
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import java.io.IOException;
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import javax.servlet.ServletException;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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/**
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* A startup handler to populate the datastore with example entities.
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*/
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public class StartupServlet extends HttpServlet {
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static final String IS_POPULATED_ENTITY = "IsPopulated";
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static final String IS_POPULATED_KEY_NAME = "is-populated";
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@Override
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protected void doGet(HttpServletRequest req, HttpServletResponse resp)
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throws ServletException, IOException {
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resp.setContentType("text/plain");
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DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
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Key isPopulatedKey = KeyFactory.createKey(IS_POPULATED_ENTITY, IS_POPULATED_KEY_NAME);
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boolean isAlreadyPopulated;
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try {
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datastore.get(isPopulatedKey);
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isAlreadyPopulated = true;
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} catch (EntityNotFoundException expected) {
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isAlreadyPopulated = false;
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}
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if (isAlreadyPopulated) {
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resp.getWriter().println("ok");
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return;
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}
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// [START create_entity_with_geopt_property]
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Entity station = new Entity("GasStation");
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station.setProperty("brand", "Ocean Ave Shell");
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station.setProperty("location", new GeoPt(37.7913156f, -122.3926051f));
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datastore.put(station);
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// [END create_entity_with_geopt_property]
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station = new Entity("GasStation");
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station.setProperty("brand", "Charge Point Charging Station");
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station.setProperty("location", new GeoPt(37.7909778f, -122.3929963f));
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datastore.put(station);
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station = new Entity("GasStation");
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station.setProperty("brand", "76");
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station.setProperty("location", new GeoPt(37.7860533f, -122.3940325f));
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datastore.put(station);
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datastore.put(new Entity(isPopulatedKey));
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resp.getWriter().println("ok");
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}
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}

‎appengine/datastore/geo/src/main/webapp/WEB-INF/appengine-web.xml

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<?xml version="1.0" encoding="utf-8"?>
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<!--
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Copyright 2016 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
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<application>YOUR-PROJECT-ID</application>
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<version>YOUR-VERSION-ID</version>
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<threadsafe>true</threadsafe>
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</appengine-web-app>

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