How to make Google map communicate with your Servlet

Steps:

1. Build a servlet
2. Build  Ajax and  Google map functions
3. Make the connection with XML

Technologies:

• Java
• Javascript
• XML
• HTML

Code:

1. Servlet code

 public class GpsServlet extends HttpServlet{
  
      public void doGet(HttpServletRequest request, HttpServletResponse response) throws  ServletException, IOException {  
         
                 PrintWriter out = response.getWriter();  

         // GPS coordinates (+ for Noth or East, - for South or West)        
                out.write("+45.508831, -73.566197");
                                
}
}     

2. Javascript code

// -------------------------------------------------------//  Ajax code

//Gets the browser specific XmlHttpRequest Object

 function getXmlHttpRequestObject2() {
  
    if (window.XMLHttpRequest) {
    return new XMLHttpRequest(); //To support the browsers IE7+, Firefox, Chrome, Opera, Safari
    }
    else if(window.ActiveXObject) {
    return new ActiveXObject("Microsoft.XMLHTTP"); // For the browsers IE6, IE5
    }
    else {
    alert("Error due to old verion of browser upgrade your browser");
    }
    }

//Store the browser specific XmlHttpRequest Object in a variable

    var rcvReq2 = getXmlHttpRequestObject2();
    

//Gets the current messages from the server

    function alterContent2() {
    if (rcvReq2.readyState == 4 || rcvReq2.readyState == 0) {

// The servlet url is gpsserv as configured in the XML file
    rcvReq2.open("GET", 'gpsserv', true);
    rcvReq2.onreadystatechange = handleAlterContent2;
    rcvReq2.send(null);
    }
    }
    

//Function for handling the return of servlet data

    function handleAlterContent2() {
    if (rcvReq2.readyState == 4) {
   
        var responseTextVar = rcvReq2.responseText;

//Split the text into 2 parts: the first one is latitude, the second one the longitude
        var item=responseTextVar.split(',');
        var lat =item[0];
        var lng =item[1];
       
// -------------------------------------------------------// Ajax code end

// -------------------------------------------------------// Google map code
             
// Create a variable holding your GPS coordinates
   var myLatlng = new google.maps.LatLng(lat, lng);

// Set map options for zoom and position
   var mapOptions =  zoom: 15, center: myLatlng};

//Create an id for your map
   var map = new google.maps.Map(document.getElementById('my_map'), mapOptions);

// Create a text that will be displayed on a infowindow
   var contentString =
              '<div id="content">'+                     
              '<em id="firstHeading" class="firstHeading" style="color:#FF4000" >Synaps21 |</em>'+       
              '<b style="color:#FF00BF">|| This is my map ! '  + '</b>'
                 +                              
              '</div>';

// Create a infowindow
  var infowindow = new google.maps.InfoWindow({
              content: contentString
          });

// Create  a marker
 var marker = new google.maps.Marker({
              position: myLatlng,
              map: map,
              title: 'Synaps21',
              icon: 'http://maps.google.com/mapfiles/ms/icons/green-dot.png'

// You can change the marker color
              //icon: 'http://maps.google.com/mapfiles/ms/icons/orange-dot.png'
             // icon: 'http://maps.google.com/mapfiles/ms/icons/red-dot.png'
          });

// Make the marker open a infowindow on click
          google.maps.event.addListener(marker, 'click', function() {
            infowindow.open(map,marker);
          });
       
// --------------------------------------------------//  Google map code end
    }
    }

//Load function
 google.maps.event.addDomListener(window, 'load', init);

3. XML code

<servlet>
        <servlet-name>gpsserv</servlet-name>
        <servlet-class>mypackage.GpsServlet</servlet-class>
    </servlet>
       
    <servlet-mapping>
        <servlet-name>gpsserv</servlet-name>
        <url-pattern>gpsserv</url-pattern>
    </servlet-mapping>

Keywords:

• Google map
• Java EE
• JavaScript
• Ajax
• JQuery