Parse http GET response body

Question

I am connecting with a website and its api to retrieve data. My code below does that and gets the response body, but how do I parse that response body? Will I have to create my own function that will have to search for the terms that I want and then get the subcontents of each term? or is there already a library that I can use that can do that for me?

private class GetResultTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {
      String response = "";

        DefaultHttpClient client = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet("https://api.bob.com/2.0/shelves/45?client_id=no&whitespace=1");
        try {
          HttpResponse execute = client.execute(httpGet);
          InputStream content = execute.getEntity().getContent();

          BufferedReader buffer = new BufferedReader(new InputStreamReader(content));
          String s = "";
          while ((s = buffer.readLine()) != null) {
            response += s;
          }

        } catch (Exception e) {
          e.printStackTrace();
        }

      return response;
    }

    @Override
    protected void onPostExecute(String result) {
      apiStatus.setText(result); //setting the result in an EditText
    }
  }

Response Body

{
"id": 415,
"url": "http://bob.com/45/us-state-capitals-flash-cards/",
"title": "U.S. State Capitals",
"created_by": "bub12",
"term_count": 50,
"created_date": 1144296408,
"modified_date": 1363506943,
"has_images": false,
"subjects": [
    "unitedstates",
    "states",
    "geography",
    "capitals"
],
"visibility": "public",
"has_access": true,
"description": "List of the U.S. states and their capitals",
"has_discussion": true,
"lang_terms": "en",
"lang_definitions": "en",
"creator": {
    "username": "bub12",
    "account_type": "plus",
    "profile_image": "https://jdfkls.dfsldj.jpg"
},
"terms": [
    {
        "id": 15407,
        "term": "Montgomery",
        "definition": "Alabama",
        "image": null
    },
    {
        "id": 15455,
        "term": "Juneau",
        "definition": "Alaska",
        "image": null
    },

    {
        "id": 413281851,
        "term": "Tallahassee",
        "definition": "Florida",
        "image": null
    },
    {
        "id": 413281852,
        "term": "Atlanta",
        "definition": "Georgia",
        "image": null
    }
  ]
}

Answer 1

/That's JSON, you can use a library like Jackson r Gson to deserialize it.

http://jackson.codehaus.org/ http://code.google.com/p/google-gson/

You can map your Java objects to the Json or deserialize it like a generic object.

Answer 2

That data format is JSON (JavaScript Object Notation). So all you need is an android-compatible JSON parser, like GSON , and you're good to go.

Answer 3

Spring's RestTemplate is so simple that it will automatically unmarshal (ie parse) the response body directly into Java objects that match the JSON format of the response:

First, define your Java classes to match the data format, using JAXB annotations if necessary. Here is a somewhat simplified model based on your response body:

@XmlRootElement
class MyResponseData {
    long id;
    String url;
    String title;
    String created_by;
    int term_count;
    int created_date;
    int modified_date;
    boolean has_images;
    List<String> subjects;
    Creator creator;
    List<Term> terms;
}

class Creator {
    String username;
    String account_type;
    String profile_image;
}

class Term {
    long id;
    String term;
    String definition;
    String image;
}

Then you just make the request with Spring's RestTemplate

String url = "https://api.bob.com/2.0/shelves/45?client_id=no&whitespace=1";
RestTemplate template = new RestTemplate();
MyResponseData body = template.getForObject(url, MyResponseData.class);

3 lines of code make the request and get the response body as a Java object. It's doesn't get much simpler.

http://static.springsource.org/spring/docs/current/javadoc-api/org/springframework/web/client/RestTemplate.html

Answer 4

Add following JSONParser.java class in your package and use like,

YourClass.java

JSONObject json = jParser.getJSONFromUrl(YOUR_URL_TO_JSON);

try {
        // Getting Array of terms
    JSONArray terms = json.getJSONArray("terms");

    // looping through All Contacts
    for(int i = 0; i < terms.length; i++){

         JSONObject termsJsonObject= terms.getJSONObject(i);

             String id = termsJsonObject.getJSONObject("id").toString();
             String term = termsJsonObject.getJSONObject("term").toString();
             String definition = termsJsonObject.getJSONObject("definition").toString();
             String image = termsJsonObject.getJSONObject("image").toString();

             // do  your operations using these values
         }
  }
  catch (JSONException e) {
        e.printStackTrace();
    return "";
  }

JSONParser.java

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    public JSONObject getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();          

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}