Accept existing websocket client as parameter

The main motivation is to make possible to the user of the library to pass
its own websocket client: this way, the developer can configure and/or
enable/disable additionnal features of the client (ping to keep the connection alive
with OkHttp, or configure timeouts for example)

Author: flolom

lib/src/main/java/ua/naiksoftware/stomp/OkHttpConnectionProvider.java

@@ -25,18 +25,20 @@
 
     private final String mUri;
     private final Map<String, String> mConnectHttpHeaders;
+    private final OkHttpClient mOkHttpClient;
 
     private final List<Subscriber<? super LifecycleEvent>> mLifecycleSubscribers;
     private final List<Subscriber<? super String>> mMessagesSubscribers;
 
     private WebSocket openedSocked;
 
 
-    /* package */ OkHttpConnectionProvider(String uri, Map<String, String> connectHttpHeaders) {
+    /* package */ OkHttpConnectionProvider(String uri, Map<String, String> connectHttpHeaders, OkHttpClient okHttpClient) {
         mUri = uri;
         mConnectHttpHeaders = connectHttpHeaders != null ? connectHttpHeaders : new HashMap<>();
         mLifecycleSubscribers = new ArrayList<>();
         mMessagesSubscribers = new ArrayList<>();
+        mOkHttpClient = okHttpClient;
     }
 
     @Override
@@ -67,15 +69,12 @@ private void createWebSocketConnection() {
             throw new IllegalStateException("Already have connection to web socket");
         }
 
-        OkHttpClient okHttpClient = new OkHttpClient.Builder()
-                .build();
-
         Request.Builder requestBuilder = new Request.Builder()
                 .url(mUri);
 
         addConnectionHeadersToBuilder(requestBuilder, mConnectHttpHeaders);
 
-        openedSocked = okHttpClient.newWebSocket(requestBuilder.build(),
+        openedSocked = mOkHttpClient.newWebSocket(requestBuilder.build(),
                 new WebSocketListener() {
                     @Override
                     public void onOpen(WebSocket webSocket, Response response) {

lib/src/main/java/ua/naiksoftware/stomp/Stomp.java

@@ -4,6 +4,7 @@
 
 import java.util.Map;
 
+import okhttp3.OkHttpClient;
 import ua.naiksoftware.stomp.client.StompClient;
 
 /**
@@ -19,7 +20,7 @@
 public class Stomp {
 
     public static StompClient over(Class clazz, String uri) {
-        return over(clazz, uri, null);
+        return over(clazz, uri, null, null);
     }
 
     /**
@@ -30,10 +31,34 @@ public static StompClient over(Class clazz, String uri) {
      * @return StompClient for receiving and sending messages. Call #StompClient.connect
      */
     public static StompClient over(Class clazz, String uri, Map<String, String> connectHttpHeaders) {
+        return over(clazz, uri, connectHttpHeaders, null);
+    }
+
+    /**
+     * {@code webSocketClient} can accept the following type of clients:
+     * <ul>
+     *     <li>{@code org.java_websocket.WebSocket}: cannot accept an existing client</li>
+     *     <li>{@code okhttp3.WebSocket}: can accept a non-null instance of {@code okhttp3.OkHttpClient}</li>
+     * </ul>
+     * @param clazz class for using as transport
+     * @param uri URI to connect
+     * @param connectHttpHeaders HTTP headers, will be passed with handshake query, may be null
+     * @param webSocketClient Existing client that will be used to open the WebSocket connection, may be null to use default client
+     * @return StompClient for receiving and sending messages. Call #StompClient.connect
+     */
+    public static StompClient over(Class clazz, String uri, Map<String, String> connectHttpHeaders, Object webSocketClient) {
         if (clazz == WebSocket.class) {
+
+            if (webSocketClient != null) {
+                throw new IllegalArgumentException("You cannot pass a webSocketClient with 'org.java_websocket.WebSocket'. use null instead.");
+            }
+
             return createStompClient(new WebSocketsConnectionProvider(uri, connectHttpHeaders));
         } else if (clazz == okhttp3.WebSocket.class) {
-            return createStompClient(new OkHttpConnectionProvider(uri, connectHttpHeaders));
+
+            OkHttpClient okHttpClient = getOkHttpClient(webSocketClient);
+
+            return createStompClient(new OkHttpConnectionProvider(uri, connectHttpHeaders, okHttpClient));
         }
 
         throw new RuntimeException("Not supported overlay transport: " + clazz.getName());
@@ -42,4 +67,17 @@ public static StompClient over(Class clazz, String uri, Map<String, String> conn
     private static StompClient createStompClient(ConnectionProvider connectionProvider) {
         return new StompClient(connectionProvider);
     }
+
+    private static OkHttpClient getOkHttpClient(Object webSocketClient) {
+        if (webSocketClient != null) {
+            if (webSocketClient instanceof OkHttpClient) {
+                return (OkHttpClient) webSocketClient;
+            } else {
+                throw new IllegalArgumentException("You must pass a non-null instance of an 'okhttp3.OkHttpClient'. Or pass null to use a default websocket client.");
+            }
+        } else {
+            // default http client
+            return new OkHttpClient();
+        }
+    }
 }