HTTPResponse as JSON in Java

Question

I was trying to get an JSONObject from a HTTP response.

try
    {   
        GetMethod postMethod = new GetMethod();
        postMethod.setURI(new URI(url, true));
        postMethod.setRequestHeader("Accept", "application/json");
        httpClient.executeMethod(postMethod);
        String resp=postMethod.getResponseBodyAsString();
        org.json.JSONTokener tokener = new org.json.JSONTokener(resp);
        finalResult = new org.json.JSONArray(tokener);

        return finalResult;
    }

But I got a runtime warning as

Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.

Should I get the response as stream as suggested by the JVM ? If so, how could I parse the JSON from it ?

Answer 1

Has your server been set up to inform clients how big its responses are? If not, your server is streaming the data, and it's technically impossible to tell how much buffer space is required to deal with the response, warranting a warning that something potentially dangerous is going on.

Answer 2

if you want to send jsonObjects from server suppose (tomcat server)

For server side-

creating jsonobjects-

I have Called toJson() for creating jsonobjects this is the implementation-

final JSONObject arr = new JSONObject();

for (int i = 0; i < contactStatus.size(); i++) {
    ContactStatus contactObject = contactStatus.get(i);

    try {
        arr.put(String.valueOf(i), toJson(value1, value2,, value3));
    } catch (JSONException e) {

     catch block e.printStackTrace();
    }
}

//Here we serialize the stream to a String.
final String output = arr.toString();
response.setContentLength(output.length());
out.print(output);//out is object of servlet output stream.

public static Object toJsonForContact(String value1, boolean value2, double value3) throws JSONException {

    JSONObject contactObject = new JSONObject();
    contactObject.put("id", id);
    contactObject.put("status", value1);
    contactObject.put("distance", value2);
    contactObject.put("relation", value3);
    return contactObject;
}

so your jsonobjects are ready for sending we write these objects to ServletoutputStream.

in client side-

while ((ReadResponses = in.readLine()) != null) {
        Constants.Response_From_server = ReadResponses;

        if (Constants.Response_From_server.startsWith("{")) {
            ListOfContactStatus = new ArrayList<ContactStatus>();
            ContactStatus contactStatusObject;

            try {
                JSONObject json = new JSONObject(Constants.Response_From_server);

                for (int i = 0; i < json.length(); i++) {
                    contactStatusObject = new ContactStatus();

                    JSONObject json1 = json.getJSONObject(String.valueOf(i));
                    System.out.println("" + json1.getString("id"));
                    System.out.println("" + json1.getBoolean("status"));
                    System.out.println("" + json1.getDouble("distance"));

                    contactStatusObject.setId(json1.getString("id"));
                    contactStatusObject.setStatus(json1.getBoolean("status"));
                    contactStatusObject.setDistance((float) json1.getDouble("distance"));
                    ListOfContactStatus.add(contactStatusObject);
                    System.out.println("HTTPTransport:sendMessage  Size of ListOfContactStatus" + ListOfContactStatus.size());
                }
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

Answer 3

You can easily generate JSonObject usin Java EE 7. The sample code.

    JsonReader reader = Json.createReader(new URI(url, true));
    JsonObject jsonObject=reader.readObject();

For details information go through to the link. http://docs.oracle.com/javaee/7/tutorial/doc/jsonp003.htm#BABHAHIA