$('#saveBtn').click(function() {
    $.ajax({
        type:'POST',
        url: '?????' ,
        success: function (result) {
            console.log(result);
        }
    });

public class ManageClients extends HttpServlet{

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    bla bla bla

   }

<servlet>
    <servlet-name>Clients</servlet-name>
    <servlet-class>com.atp.servlets.Controller.ManageClients</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>Clients</servlet-name>
    <url-pattern>/Clients</url-pattern>
</servlet-mapping>