Added longpoll listener

sdk/src/main/java/com/vk/api/sdk/longpolling/LongPollingListener.java

@@ -0,0 +1,106 @@
+package com.vk.api.sdk.longpolling;
+
+import com.google.gson.JsonObject;
+import com.vk.api.sdk.client.VkApiClient;
+import com.vk.api.sdk.client.actors.Actor;
+import com.vk.api.sdk.client.actors.GroupActor;
+import com.vk.api.sdk.client.actors.UserActor;
+import com.vk.api.sdk.exceptions.ApiException;
+import com.vk.api.sdk.exceptions.ClientException;
+import com.vk.api.sdk.exceptions.LongPollServerKeyExpiredException;
+import com.vk.api.sdk.objects.callback.longpoll.responses.GetLongPollEventsResponse;
+import com.vk.api.sdk.objects.groups.LongPollServer;
+import com.vk.api.sdk.objects.messages.LongpollParams;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+
+public class LongPollingListener {
+    private final VkApiClient vk;
+    private final Actor actor;
+    private final int groupId;
+
+    private String server;
+    private String key;
+    private int ts;
+
+    private final Map<String, Consumer<JsonObject>> handlers;
+
+    private static Logger logger = LoggerFactory.getLogger(LongPollingListener.class);
+
+    public LongPollingListener(final VkApiClient vk, final GroupActor actor, int groupId) {
+        this.vk = vk;
+        this.actor = actor;
+        this.groupId = groupId;
+        this.handlers = new HashMap<>();
+    }
+
+    public LongPollingListener(final VkApiClient vk, final UserActor actor) {
+        this.vk = vk;
+        this.actor = actor;
+        this.groupId = -1;
+        this.handlers = new HashMap<>();
+    }
+
+    protected void connect() throws ClientException, ApiException {
+        if (actor instanceof GroupActor) {
+            final LongPollServer longPollServer = vk.groups()
+                    .getLongPollServer((GroupActor) actor, groupId)
+                    .execute();
+
+            this.server = longPollServer.getServer();
+            this.key = longPollServer.getKey();
+            this.ts = Integer.parseInt(longPollServer.getTs());
+        } else {
+            final LongpollParams longPollServer = vk.messages()
+                    .getLongPollServer((UserActor) actor)
+                    .execute();
+
+            this.server = longPollServer.getServer();
+            this.key = longPollServer.getKey();
+            this.ts = longPollServer.getTs();
+        }
+
+    }
+
+    public void startListening() throws ClientException, ApiException {
+        while (true) {
+            try {
+                GetLongPollEventsResponse response = vk.longPoll()
+                        .getEvents(server, key, ts)
+                        .waitTime(30)
+                        .execute();
+
+                ts = response.getTs();
+                List<JsonObject> updates = response.getUpdates();
+
+
+                updates.forEach(jsonObject -> {
+                    final String type = jsonObject.get("type").getAsString();
+                    Consumer<JsonObject> handler = handlers.get(type);
+                    if(handler != null) {
+                        handler.accept(jsonObject);
+                    }
+                });
+
+            } catch (LongPollServerKeyExpiredException e) {
+                logger.info("Key expired. Regeneration...");
+                connect();
+            } catch (ClientException e) {
+                logger.error("Long poll error", e);
+                connect();
+            }
+
+        }
+    }
+
+
+    public LongPollingListener addHandler(String event, Consumer<JsonObject> handler) {
+        handlers.put(event, handler);
+        return this;
+    }
+}