PositioningServlet.java
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package servlet;
import core.repository.Location;
import core.service.PositioningService;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Inet4Address;
import java.net.InetAddress;
import static java.lang.Thread.sleep;
/**
* Servlet handling positioning request coming from clients.
*
* Created by Guillaume on 15/05/2017.
*/
public class PositioningServlet extends HttpServlet{
@Override
public void service (final HttpServletRequest servletRequest, final HttpServletResponse servletResponse)
throws ServletException, IOException {
String clientMacAddr = servletRequest.getParameter("CLIENT_MAC_ADDR");
PositioningService posServ = new PositioningService();
multicastPositioningRequest(clientMacAddr);
Location loc;
do{
try{
sleep(500L);
} catch (InterruptedException e) {
e.printStackTrace();
}
loc = posServ.getLocation(clientMacAddr);
}while(loc==null);
servletResponse.setContentType("application/json");
servletResponse.getWriter().print(String.format("{\"x\": \"%f\", \"y\": \"%f\", \"map\": \"%d\"}", loc.getX(), loc.getY(), loc.getMap().getId()));
}
@Override
public void doGet(final HttpServletRequest servletRequest, final HttpServletResponse servletResponse)
throws ServletException, IOException {
service(servletRequest, servletResponse);
}
@Override
public void doPost(final HttpServletRequest servletRequest, final HttpServletResponse servletResponse)
throws ServletException, IOException {
service(servletRequest, servletResponse);
}
/**
* Method broadcasting UPD request to AP, request asking for positioning data.
*
* @param clientMacAddress mac address of client on which ap's measurement will be based
*/
private void multicastPositioningRequest(String clientMacAddress){
try (DatagramSocket socket = new DatagramSocket(4445)){
byte[] buf;
String dString = "{\"LOCATE\": \"" + clientMacAddress + "\", \"SERV\": \"" + Inet4Address.getLocalHost().getHostAddress()+"\"}";
buf = dString.getBytes();
// send it
InetAddress group = InetAddress.getByName("10.255.255.255");
DatagramPacket packet = new DatagramPacket(buf, buf.length, group, 4446);
socket.send(packet);
} catch (IOException e) {
e.printStackTrace();
}
}
}