feat: implement view-based Java RoutesActivity and RouteRepository

Author: dkhawk

Maps3DSamples/ApiDemos/java-app/src/main/java/com/example/maps3djava/routes/RouteRepository.java

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.maps3djava.routes;
+
+import com.google.android.gms.maps.model.LatLng;
+import org.json.JSONArray;
+import org.json.JSONObject;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+
+/**
+ * Represents the decoded route and step waypoints payload for the Java Routes API sample.
+ */
+class RouteData {
+    private final String encodedPolyline;
+    private final List<LatLng> navPoints;
+
+    public RouteData(String encodedPolyline, List<LatLng> navPoints) {
+        this.encodedPolyline = encodedPolyline;
+        this.navPoints = navPoints;
+    }
+
+    public String getEncodedPolyline() {
+        return encodedPolyline;
+    }
+
+    public List<LatLng> getNavPoints() {
+        return navPoints;
+    }
+}
+
+/**
+ * A data repository responsible for executing background network tasks to compute driving
+ * directions using the Google Maps Routes API (v2) in Java.
+ */
+public class RouteRepository {
+
+    /**
+     * Returns a Callable to fetch the route in a background thread pool.
+     *
+     * @param apiKey The API key to authenticate client requests.
+     * @param origin Starting coordinate.
+     * @param destination Destination coordinate.
+     * @return A Callable producing [RouteData].
+     */
+    public Callable<RouteData> fetchRouteCallable(String apiKey, LatLng origin, LatLng destination) {
+        return () -> {
+            URL url = new URL("https://routes.googleapis.com/directions/v2:computeRoutes");
+            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+            connection.setRequestMethod("POST");
+            connection.setRequestProperty("Content-Type", "application/json");
+            connection.setRequestProperty("X-Goog-Api-Key", apiKey);
+            connection.setRequestProperty("X-Goog-FieldMask", "routes.polyline.encodedPolyline,routes.legs.steps.startLocation");
+            connection.setDoOutput(true);
+
+            // Structure the JSON request body manually using standard JSONObjects
+            JSONObject requestBody = new JSONObject();
+            
+            JSONObject originLatLng = new JSONObject()
+                    .put("latitude", origin.latitude)
+                    .put("longitude", origin.longitude);
+            requestBody.put("origin", new JSONObject()
+                    .put("location", new JSONObject().put("latLng", originLatLng)));
+
+            JSONObject destLatLng = new JSONObject()
+                    .put("latitude", destination.latitude)
+                    .put("longitude", destination.longitude);
+            requestBody.put("destination", new JSONObject()
+                    .put("location", new JSONObject().put("latLng", destLatLng)));
+
+            requestBody.put("travelMode", "DRIVE");
+
+            // Stream payload to connection output
+            try (OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream())) {
+                writer.write(requestBody.toString());
+                writer.flush();
+            }
+
+            int responseCode = connection.getResponseCode();
+            if (responseCode == HttpURLConnection.HTTP_OK) {
+                StringBuilder response = new StringBuilder();
+                try (BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
+                    String line;
+                    while ((line = reader.readLine()) != null) {
+                        response.append(line);
+                    }
+                }
+
+                JSONObject jsonResponse = new JSONObject(response.toString());
+                JSONArray routes = jsonResponse.getJSONArray("routes");
+                if (routes.length() > 0) {
+                    JSONObject route = routes.getJSONObject(0);
+                    JSONObject polyline = route.getJSONObject("polyline");
+                    String encodedPolyline = polyline.getString("encodedPolyline");
+
+                    List<LatLng> navPoints = new ArrayList<>();
+                    JSONArray legs = route.optJSONArray("legs");
+                    if (legs != null && legs.length() > 0) {
+                        JSONObject leg = legs.getJSONObject(0);
+                        JSONArray steps = leg.optJSONArray("steps");
+                        if (steps != null) {
+                            for (int i = 0; i < steps.length(); i++) {
+                                JSONObject step = steps.getJSONObject(i);
+                                JSONObject startLocation = step.optJSONObject("startLocation");
+                                if (startLocation != null) {
+                                    JSONObject latLngObj = startLocation.getJSONObject("latLng");
+                                    navPoints.add(new LatLng(
+                                            latLngObj.getDouble("latitude"),
+                                            latLngObj.getDouble("longitude")
+                                    ));
+                                }
+                            }
+                        }
+                    }
+                    navPoints.add(destination); // Cap route off with final destination
+                    return new RouteData(encodedPolyline, navPoints);
+                } else {
+                    throw new Exception("No route details returned from the server.");
+                }
+            } else {
+                StringBuilder errorResponse = new StringBuilder();
+                try (BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getErrorStream()))) {
+                    String line;
+                    while ((line = reader.readLine()) != null) {
+                        errorResponse.append(line);
+                    }
+                }
+                throw new Exception("HTTP error " + responseCode + ": " + errorResponse);
+            }
+        };
+    }
+}