Java tutorial
/** * Copyright 2015 Google Inc. All Rights Reserved. * * 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.gcm.samples.friendlyping; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.annotations.SerializedName; import com.google.gson.reflect.TypeToken; import org.jivesoftware.smack.util.StringUtils; import java.util.ArrayList; import java.util.Collection; import java.util.Map; import java.util.Map.Entry; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.CountDownLatch; import java.util.logging.Level; import java.util.logging.Logger; /** * FriendlyPingServer provides the logic to allow clients to register and be notified of other * clients registering. It also responds to pings from clients. */ public class FriendlyPingServer { // FriendlyPing Client. private class Client { String name; @SerializedName("registration_token") String registrationToken; @SerializedName("profile_picture_url") String profilePictureUrl; public boolean isValid() { return StringUtils.isNotEmpty(name) && StringUtils.isNotEmpty(registrationToken) && StringUtils.isNotEmpty(profilePictureUrl); } } // FriendlyGcmServer defines onMessage to handle incoming friendly ping messages. private class FriendlyGcmServer extends GcmServer { public FriendlyGcmServer(String apiKey, String senderId, String serviceName) { super(apiKey, senderId, serviceName); } @Override public void onMessage(String from, JsonObject jData) { if (jData.has("action")) { String action = jData.get("action").getAsString(); if (action.equals(REGISTER_NEW_CLIENT)) { registerNewClient(jData); } else if (action.equals("ping_client")) { String toToken = jData.get("to").getAsString(); String senderToken = jData.get("sender").getAsString(); if (StringUtils.isNotEmpty(toToken) && StringUtils.isNotEmpty(senderToken)) { pingClient(toToken, senderToken); } else { logger.info("Unable to ping unless to and sender tokens are available."); } } } else { logger.info("No action found. Message received missing action."); } } } private static final Logger logger = Logger.getLogger("FriendlyPingServer"); private static final String SENDER_ID = "<SENDER_ID>"; private static final String SERVER_API_KEY = "<SERVER_API_KEY>"; // Actions private static final String REGISTER_NEW_CLIENT = "register_new_client"; private static final String BROADCAST_NEW_CLIENT = "broadcast_new_client"; private static final String SEND_CLIENT_LIST = "send_client_list"; private static final String PING_CLIENT = "ping_client"; // Keys private static final String ACTION_KEY = "action"; private static final String CLIENT_KEY = "client"; private static final String CLIENTS_KEY = "clients"; private static final String DATA_KEY = "data"; private static final String SENDER_KEY = "sender"; private static final String NEW_CLIENT_TOPIC = "/topics/newclient"; private static final String PING_TITLE = "Friendly Ping!"; private static final String PING_ICON = "mipmap/ic_launcher"; private static final String CLICK_ACTION = "ping_received"; public static final String SERVICE_NAME = "Friendly Ping Server"; // Store of clients registered with FriendlyPingServer. private Map<String, Client> clientMap; // Listener responsible for handling incoming registrations and pings. private FriendlyGcmServer friendlyGcmServer; // Gson helper to assist with going to and from JSON and Client. private Gson gson; public FriendlyPingServer(String apiKey, String senderId) { clientMap = new ConcurrentHashMap<String, Client>(); Client serverClient = createServerClient(); clientMap.put(serverClient.registrationToken, serverClient); gson = new GsonBuilder().create(); friendlyGcmServer = new FriendlyGcmServer(apiKey, senderId, SERVICE_NAME); } /** * Create a Client object to be used in responses to pings to the server. * * @return Server Client. */ private Client createServerClient() { Client client = new Client(); client.name = "Larry"; client.registrationToken = SENDER_ID + "@gcm.googleapis.com"; client.profilePictureUrl = "https://lh3.googleusercontent.com/-Y86IN-vEObo/AAAAAAAAAAI/AAAAAAADO1I/QzjOGHq5kNQ/photo.jpg?sz=50"; return client; } /** * Create Client from given JSON data, add client to client list, broadcast newly registered * client to all previously registered clients and send client list to new client. * * @param jData JSON data containing properties of new Client. */ private void registerNewClient(JsonObject jData) { Client newClient = gson.fromJson(jData, Client.class); if (newClient.isValid()) { addClient(newClient); broadcastNewClient(newClient); sendClientList(newClient); } else { logger.log(Level.WARNING, "Could not unpack received data into a Client."); } } /** * Add given client to Map of Clients. * * @param client Client to be added. */ private void addClient(Client client) { clientMap.put(client.registrationToken, client); } /** * Broadcast the newly registered client to clients that have already been registered. The * broadcast is sent via the PubSub topic "/topics/newuser" all registered clients should be * subscribed to this topic. * * @param client Newly registered client. */ private void broadcastNewClient(Client client) { JsonObject jBroadcast = new JsonObject(); JsonObject jData = new JsonObject(); jData.addProperty(ACTION_KEY, BROADCAST_NEW_CLIENT); JsonObject jClient = gson.toJsonTree(client).getAsJsonObject(); jData.add(CLIENT_KEY, jClient); jBroadcast.add(DATA_KEY, jData); friendlyGcmServer.send(NEW_CLIENT_TOPIC, jBroadcast); } /** * Send client list to newly registered client. When a new client is registered, that client must * be informed about the other registered clients. * * @param client Newly registered client. */ private void sendClientList(Client client) { ArrayList<Client> clientList = new ArrayList(); for (Entry<String, Client> clientEntry : clientMap.entrySet()) { Client currentClient = clientEntry.getValue(); if (currentClient.registrationToken != client.registrationToken) { clientList.add(currentClient); } } JsonElement clientElements = gson.toJsonTree(clientList, new TypeToken<Collection<Client>>() { }.getType()); if (clientElements.isJsonArray()) { JsonObject jSendClientList = new JsonObject(); JsonObject jData = new JsonObject(); jData.addProperty(ACTION_KEY, SEND_CLIENT_LIST); jData.add(CLIENTS_KEY, clientElements); jSendClientList.add(DATA_KEY, jData); friendlyGcmServer.send(client.registrationToken, jSendClientList); } } /** * Send message to Client with matching toToken. The validity of to and sender tokens * should be check before this method is called. * * @param toToken Token of recipient of ping. * @param senderToken Token of sender of ping. */ private void pingClient(String toToken, String senderToken) { Client senderClient; // If the server is the recipient of the ping, send ping to sender, otherwise send ping to // toToken. if (toToken.equals(SENDER_ID + "@" + GcmServer.GCM_HOST)) { senderClient = clientMap.get(toToken); toToken = senderToken; } else { senderClient = clientMap.get(senderToken); } JsonObject jPing = new JsonObject(); JsonObject jData = new JsonObject(); jData.addProperty(ACTION_KEY, PING_CLIENT); jData.addProperty(SENDER_KEY, senderClient.registrationToken); // Create notification that is handled appropriately on the receiving platform. JsonObject jNotification = new JsonObject(); jNotification.addProperty("body", senderClient.name + " is pinging you."); jNotification.addProperty("title", PING_TITLE); jNotification.addProperty("icon", PING_ICON); jNotification.addProperty("sound", "default"); jNotification.addProperty("click_action", CLICK_ACTION); jPing.add(DATA_KEY, jData); jPing.add("notification", jNotification); friendlyGcmServer.send(toToken, jPing); } public static void main(String[] args) { // Initialize FriendlyPingServer with appropriate API Key and SenderID. new FriendlyPingServer(SERVER_API_KEY, SENDER_ID); // Keep main thread alive. try { CountDownLatch latch = new CountDownLatch(1); latch.await(); } catch (InterruptedException e) { logger.log(Level.SEVERE, "An error occurred while latch was waiting.", e); } } }