Return JSON from servlet

Question

It is a very basic request-response test. Browser sends \"hello from browser\" to servlet using jQuery $.ajax API, and servlet receives this message, then create a JSON obje

Answer 1

I was having the same problem. It was working well on Firefox but not on IE... I found out reading this post that my problem was related to the 'Content-Type'. The problem seems that that IE has problem with 'charset=UTF8'. However, if you use 'charset=UTF-8' (with a dash) it is then working! Your Content-Type should then be: application/json;charset=UTF-8

Answer 2

<% 
     Gson gs = new Gson();
     BeanHelpBH bh = new BeanHelpBH();
     List<Baihatmoi> lst = bh.getTenbaihatbyName("Ao moi ca mau");
    String bha = gs.toJson(lst);
    response.setContentType("application/json");
    response.setCharacterEncoding("UTF-8");
    out.print(bha);
    out.flush();


%>

  script : 
        <script>
             $(document).ready(function(){
               $.get('jsontest.jsp',function(data){
            [enter image description here][1] console.log(data);

              });

           });
        </script>

Answer 3

using Gson you can send json response

@WebServlet(urlPatterns = {"/jsonResponse"})
public class JsonResponse extends HttpServlet {

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("application/json");
    response.setCharacterEncoding("utf-8");
    Student student = new Student(12, "Ram Kumar", "Male", "1234565678");
    Subject subject1 = new Subject(1, "Computer Fundamentals");
    Subject subject2 = new Subject(2, "Computer Graphics");
    Subject subject3 = new Subject(3, "Data Structures");
    Set subjects = new HashSet();
    subjects.add(subject1);
    subjects.add(subject2);
    subjects.add(subject3);
    student.setSubjects(subjects);
    Address address = new Address(1, "Street 23 NN West ", "Bhilai", "Chhattisgarh", "India");
    student.setAddress(address);
    Gson gson = new Gson();
    String jsonData = gson.toJson(student);
    PrintWriter out = response.getWriter();
    try {
        out.println(jsonData);
    } finally {
        out.close();
    }

}

}

for more json response from servlet in java

Answer 4

IE caches AJAX requests aggressively (more than Firefox, Chrome, and Safari, anyway). Sometimes you need to set cache header controller when request. Like cache:false. I tried to fix your code like this

request.setCharacterEncoding("utf8");
        //response.setCharacterEncoding("utf8");
        response.setContentType("application/json");
        PrintWriter out = response.getWriter();
        JSONObject jsonObj = (JSONObject) JSONValue.parse(request.getParameter("para"));
        System.out.println(jsonObj.get("message"));
        JSONObject obj = new JSONObject();
        obj.put("message", "hello from server");
        out.print(obj.toString());

I changed your response content-type from application/json; charset=utf8 to just application/json and that worked.