Java Servlet on Tomcat called from AJAX - ajax

Question

I want to call a Servlet from ajax in a Java WebApp, using Tomcat7.
I used the annotation #WebServlet("/VServlet") to mapping it in the WebApp, because of Tomcat7 support Servlet 3.0.
I call the servlet with the jquery command "$.getJSON('VServlet', function(data){ ... });" but if I use the string 'VServlet', it doesn't work.
Only if I use the entire url 'http:// localhost:8080/WebAppName/VServlet' it works, but only in my pc. However I have to deploy it on a server that has a commercial domain name, obviously different from "localhost".
Please, can anyone tell me if there is a way to address the servlet with a relative url?
Because if I use a string like 'http://my.domain.it:8080/WebAppName/VServlet' it doesn't work on the Tomcat7 that is on the server machine.
Thanks.
------------------EDIT-----------------------
I try to explain better my problem.
I have a Java Servlet that return a json structure. The servlet is called in a javascript file that have to draw a graph in a web page, building a SVG image. I have to deploy this web app on a commercial Windows server with Tomcat7 installed.
The web app generally works. Any errors are displayed from the user point of view. Simply the image doesn't appear if I use that strings I wrote above, to call the servlet.
I suppose that the servlet doesn't respond because I use a wrong address/naming. If I use an absolute url, the servlet responds to the js caller, but I need a relative string, so if the domain name of the server will change, I won't change the code of the js file too.

Answer 1

When you call
$.getJSON('VServlet', ... );
you are making a HTTP GET request to an URL relative to the current URL. That is, if you're in /webapp/users/user.xhtml you'll be sending a request to /webapp/users/VServlet which obviously doesn't match the URL pattern of your servlet and not the thing you're trying to achieve.
You need to take into account the context path of a JSF application that's available in view as #{request.contextPath} to build up a proper absolute URL:
$.getJSON('#{request.contextPath}/VServlet', ... );
This will send a request to http://localhost:8080/webapp/VServlet.
In case you need to send request to a path relative to the root, such request URLs start with a slash, / and represent URLs relative to the root, no matter where you're right now:
$.getJSON('/VServlet', ... );
This will send a request to http://localhost:8080/VServlet.

Answer 2

if your js code is inside jsp page Instead of the code
$.getJSON('VServlet', function(data){ ... });
write
"$.getJSON('${request.contextPath}/VServlet', function(data){ ... });
other wise if this code is in some js file in a function something like
function someFunction(){
$.getJSON('VServlet', function(data){ ... });
}
and you are calling function someFunction() from jsp
then you add a parameter to the function like this -
function someFunction(url){
$.getJSON('VServlet', function(data){ ... });
}
and now call it from jsp like this -
someFunction('${request.contextPath}/VServlet')
because ${request.contextPath}/VServlet is an el tag and it will get compiled only in jsp page