MouseControlServlet.java

package ch.unifr.pai.twice.mousecontrol.server;

/*
 * Copyright 2013 Oliver Schmid
 * 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.
 */
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * The mouse control servlet gathers information from the clients and forwards them to the MouseControlPython server which then pushes them through web sockets
 * to the shared screen instance. In a future implementation, this additional step through the python web server will be overcome by simply handling the mouse
 * pointer controller on the java server instance
 * 
 * 
 * @author Oliver Schmid
 * 
 */
@WebServlet("/mouseManagerXBrowser")
public class MouseControlServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;
	public static final Integer DEFAULTPORT = 8182;

	/**
	 * Interpret the message and send it to the web socket server
	 * 
	 * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	 */
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String response = null;
		String action = req.getParameter("a");
		if (action != null) {
			if (action.equals("g")) {
				response = askController("g");
			}
			else {
				String targetUUID = req.getParameter("targetUUID");
				StringBuilder sb = new StringBuilder();
				sb.append("m@").append(targetUUID);
				sb.append("@").append(req.getParameter("uuid"));
				for (Object s : req.getParameterMap().keySet()) {
					if (!s.toString().equals("targetUUID") && !s.toString().equals("uuid"))
						sb.append("@").append(s.toString()).append("=").append(req.getParameter(s.toString()));
				}
				response = askController(sb.toString());
			}
		}
		if (response != null)
			resp.getWriter().write(response);
		resp.getWriter().close();
	}

	/**
	 * Send the data to the web socket server through a UDP socket
	 * 
	 * @param data
	 * @return
	 */
	private String askController(String data) {
		byte[] send_data = new byte[100];
		byte[] receive_data = new byte[100];
		try {
			InetAddress host = InetAddress.getLocalHost();
			Integer port = DEFAULTPORT;
			send_data = data.getBytes();
			DatagramPacket send_packet = new DatagramPacket(send_data, send_data.length, host, port);
			DatagramSocket socket = new DatagramSocket();
			socket.send(send_packet);
			DatagramPacket response_packet = new DatagramPacket(receive_data, receive_data.length);
			socket.receive(response_packet);
			socket.close();
			return new String(response_packet.getData(), 0, response_packet.getLength());
		}
		catch (SocketException e) {
			// ignore exception because there will be a new event rather soon...
			e.printStackTrace();
		}
		catch (UnknownHostException e) {
			// ignore exception because there will be a new event rather soon...
			e.printStackTrace();
		}
		catch (IOException e) {
			// ignore exception because there will be a new event rather soon...
			e.printStackTrace();
		}
		return null;
	}

}