Receiving objects from server on separate thread

src/main/java/envoy/client/Client.java

@@ -1,7 +1,5 @@
 package envoy.client;
 
-import java.io.IOException;
-import java.io.InputStream;
 import java.net.Socket;
 import java.util.Map;
 import java.util.logging.Logger;
@@ -9,6 +7,7 @@ import java.util.logging.Logger;
 import envoy.client.util.EnvoyLog;
 import envoy.data.LoginCredentials;
 import envoy.data.User;
+import envoy.exception.EnvoyException;
 import envoy.util.SerializationUtils;
 
 /**
@@ -23,10 +22,11 @@ import envoy.util.SerializationUtils;
  */
 public class Client {
 
-	private Socket	socket;
-	private Config	config	= Config.getInstance();
-	private User	sender, recipient;
-	private boolean	online;
+	private Socket			socket;
+	private Config			config	= Config.getInstance();
+	private volatile User	sender;
+	private User			recipient;
+	private boolean			online;
 
 	private static final Logger logger = EnvoyLog.getLogger(Client.class.getSimpleName());
 
@@ -34,11 +34,11 @@ public class Client {
 	 * Enters the online mode by acquiring a user ID from the server.
 	 *
 	 * @param credentials the login credentials of the user
-	 * @throws IOException if the online mode could not be entered or the request
-	 *                     failed for some other reason
+	 * @throws Exception if the online mode could not be entered or the request
+	 *                   failed for some other reason
 	 * @since Envoy v0.2-alpha
 	 */
-	public void onlineInit(LoginCredentials credentials) throws IOException {
+	public void onlineInit(LoginCredentials credentials) throws Exception {
 		logger.info(String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
 		logger.info("Successfully connected to server.");
@@ -47,14 +47,20 @@ public class Client {
 		logger.finest("Sending login credentials...");
 		SerializationUtils.writeBytesWithLength(credentials, socket.getOutputStream());
 
-		// Read response (user object)
-		InputStream in = socket.getInputStream();
+		// Create message receiver
+		Receiver receiver = new Receiver(socket.getInputStream());
 
-		// Read object
-		try {
-			sender = SerializationUtils.read(in, User.class);
-		} catch (ClassNotFoundException e) {
-			throw new IOException(e);
+		// Register user creation processor
+		receiver.registerProcessor(User.class, sender -> { logger.info("Acquired user object " + sender); this.sender = sender; });
+
+		// Start receiver
+		new Thread(receiver).start();
+
+		// Wait for a maximum of five seconds to acquire the sender object
+		long start = System.currentTimeMillis();
+		while (sender == null) {
+			if (System.currentTimeMillis() - start > 5000) throw new EnvoyException("Did not log in after 5 seconds");
+			Thread.sleep(500);
 		}
 
 		online = true;

src/main/java/envoy/client/ObjectProcessor.java

@@ -0,0 +1,15 @@
+package envoy.client;
+
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>ObjectProcessor.java</strong><br>
+ * Created: <strong>30.12.2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.3-alpha
+ */
+public interface ObjectProcessor<T> {
+
+	void process(T input);
+}

src/main/java/envoy/client/Receiver.java

@@ -0,0 +1,50 @@
+package envoy.client;
+
+import java.io.InputStream;
+import java.io.ObjectInputStream;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import envoy.client.util.EnvoyLog;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>Receiver.java</strong><br>
+ * Created: <strong>30.12.2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.3-alpha
+ */
+public class Receiver implements Runnable {
+
+	private InputStream				in;
+	private Map<Class<?>, ObjectProcessor<?>>	processors	= new HashMap<>();
+
+	private static final Logger logger = EnvoyLog.getLogger(Receiver.class.getSimpleName());
+
+	public Receiver(InputStream in) { this.in = in; }
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public void run() {
+		try (ObjectInputStream oin = new ObjectInputStream(in)) {
+			while (true) {
+				Object obj = oin.readObject();
+				logger.finest("Received object " + obj);
+
+				// Get appropriate processor
+				ObjectProcessor processor = processors.get(obj.getClass());
+				if (processor == null)
+					logger.severe(String.format("The received object has the class %s for which no processor is defined.", obj.getClass()));
+				else
+					processor.process(obj);
+			}
+		} catch(Exception e) {
+			logger.log(Level.SEVERE, "Error on receiver thread", e);
+		}
+	}
+
+	public <T> void registerProcessor(Class<T> processorClass, ObjectProcessor<T> processor) { processors.put(processorClass, processor); }
+}

src/main/java/envoy/client/ui/Startup.java

@@ -101,6 +101,7 @@ public class Startup {
 			client.onlineInit(new LoginCredentials(userName, pass.toCharArray()));
 		} catch (Exception e1) {
 			logger.warning("Could not connect to server. Trying offline mode...");
+			e1.printStackTrace();
 			try {
 				// Try entering offline mode
 				localDB.loadUsers();