A rest api based socket client

Client.java

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import com.google.android.gms.nearby.messages.Message;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonSyntaxException;

public class Client {

	private String host;
	private String ID;
	private boolean connected;
	private Parser parser;

	private List<Listener> listeners;

	public Client() {
		listeners = new ArrayList<Listener>();
		parser = new Parser();
	}

	public void connect(String host, int port) {
		this.host = host+":"+port;
		connect();
	}

	private void connect() {
		ID = request("/register").body;
		connected = true;
		for(Listener listener : listeners) {
			try {
				listener.connected();
			} catch(Exception e) {
				e.printStackTrace();
			}
		}
		new Thread(new Runnable() {
			@Override
			public void run() {
				while(connected) {
					Response response = request("/fetch/"+ID);
					if(response.statusCode == 400) {
						System.out.println("Disconnecting");
						connected = false;
						for(Listener listener : listeners) {
							try {
								listener.disconnected();
							} catch(Exception e) {
								e.printStackTrace();
							}
						}
					} else if(response.body == null) {
						System.err.println("No data received");
					} else {
						try {
							JsonArray array = parser.getGson().fromJson(response.body, JsonArray.class);
							if(array.size() > 0) {
								for(JsonElement element : array) {
									Object object = parser.parse(element);
									if(object == null) {
										System.err.println("Could not parse object");
									} else {
										for(Listener listener : listeners) {
											listener.received(object);
										}
									}
								}
							}
						} catch(JsonSyntaxException e) {
							System.err.println("Malformed json");
							e.printStackTrace();
						}
					}
					try {
						Thread.sleep(5000);
					} catch(InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
		}).start();
	}

	public void close() {
		connected = false;
		request("/unregister/"+ID);
	}

	public void addListener(Listener listener) {
		listeners.add(listener);
	}

	public void sendTCP(Object object) {
		if(!connected) {
			while(!connected) {
				try {
					Thread.sleep(1000);
				} catch(InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
		System.out.println("Sending "+object);

		InputStream in = null;
		try {
			URL url = new URL(host+"/push/"+ID);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			conn.setRequestMethod("POST");
			conn.setDoOutput(true);
			parser.getGson().toJson(object, new PrintWriter(conn.getOutputStream()));
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			try {
				in.close();
			} catch(Exception e) {
				e.printStackTrace();
			}
		}
	}

	public Response request(String path) {
		Response response = new Response();
		InputStream is = null;
		try {
			URL url = new URL(host+path);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			response.statusCode = conn.getResponseCode();
			if(response.statusCode == 200) {
				StringBuffer buffer = new StringBuffer();
				is = conn.getInputStream();
				BufferedReader reader = new BufferedReader(new InputStreamReader(is));
				String line = null;
				while((line = reader.readLine()) != null) {
					buffer.append(line);
				}
				response.body = buffer.toString();
			}
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			if (is != null) {
				try {
					is.close();
				} catch(Exception e) {
					e.printStackTrace();
				}
			} 
		}
		return response;
	}

	public class Response {

		public String body;
		public int statusCode;

	}

	public class Parser {

		private Gson gson;

		public Parser() {
			gson = new Gson();
		}

		public Object parse(JsonElement body) {
			//TODO add your classes here
			try {
				return gson.fromJson(body, Message.class);
			} catch(JsonSyntaxException e) {}
			return null;
		}

		public Gson getGson() {
			return gson;
		}

		public void setGson(Gson gson) {
			this.gson = gson;
		}

	}

	public interface Listener {

		public void connected();
		public void received(Object object);
		public void disconnected();
		
	}

}