title: Liferay ajax request and JSON response
body: <p>I am new in Liferay. I used service builder to create database. I populated them manually. And eventually I could call them in JSP using <code>PersonLocalServiceUtil class</code>. 
  Now I want to use Ajax in my program. </p>
  
  <p>For example: 
  Person with attributes <code>personID</code>, <code>personWeight</code>, <code>personTemperature</code> and <code>datetime</code> are stored in database.</p>
  
  <p>I want to do an ajax call by <code>personID</code> to see his <strong>weight</strong> or <strong>Temperature</strong> graph for particular timeline. All I know, I can call list from Database to controller But I don't know How can I convert it to <code>JSON</code> obejct and forward it to JSP upon request, so that JSP won't refresh the page but display new graph.</p>