从Servlet发送JSON

Question

I write this servlet :

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

    response.setContentType("application/json");

    BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
    String json = "";
    if(br != null){
        json = br.readLine();
    }

    PrintWriter out = response.getWriter();

    out.write(json);
    out.flush();
}

Sending data via ajax request and the servlet me return them. The problem is that when I try to make me return a JSONObject created inside servlet gives me error 500.

The code that gives me this error:

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




    response.setContentType("application/json");

    BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));

    JSONObject json = new JSONObject();

    json.put("name", "federico");

    PrintWriter out = response.getWriter();

    out.print(json);
    out.flush();
}

My requestAjax is :

$.ajax({
                url: "ValidServlet",
                type: 'POST',
                data : JSON.stringify(submitFormData),
                success: function (data) {
                    alert(data.name);
                },
                error: function (data) {
                    alert('error');
                }
            });

My error is :

Failed to load resource: the server responded with a status of 500 (Internal Server Error) (17:33:34:492 | error, network)at http://localhost:8080/ProgettoProsa/ValidServlet> 

Maybe I'm wrong to return so the json?

Help me figure out where I'm fail.

Thank you all.

Answer 1

try this code to send json data with http:

    package com.nl.services.ws.sincronizacao;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.gson.Gson;

@WebServlet(value = "/TestGsonHttp")
public class TestGsonHttp extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // Your class
        MyJson m = new MyJson();
        m.setName("frederico");

        Gson g = new Gson();
        String jsonResult = g.toJson(m);

        PrintWriter writer = resp.getWriter();
        writer.print(jsonResult);
        writer.flush();
        writer.close();
    }

    class MyJson {

        private String  name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}