Parse JSON from Httpurlconnection Object

Parse JSON from HttpURLConnection object

You can get raw data using below method. BTW, this pattern is for Java 6. If you are using Java 7 or newer, please consider try-with-resources pattern.

public String getJSON(String url, int timeout) {
    HttpURLConnection c = null;
    try {
        URL u = new URL(url);
        c = (HttpURLConnection) u.openConnection();
        c.setRequestMethod("GET");
        c.setRequestProperty("Content-length", "0");
        c.setUseCaches(false);
        c.setAllowUserInteraction(false);
        c.setConnectTimeout(timeout);
        c.setReadTimeout(timeout);
        c.connect();
        int status = c.getResponseCode();

        switch (status) {
            case 200:
            case 201:
                BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
                StringBuilder sb = new StringBuilder();
                String line;
                while ((line = br.readLine()) != null) {
                    sb.append(line+"\n");
                }
                br.close();
                return sb.toString();
        }

    } catch (MalformedURLException ex) {
        Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex) {
        Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
    } finally {
       if (c != null) {
          try {
              c.disconnect();
          } catch (Exception ex) {
             Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
          }
       }
    }
    return null;
}

And then you can use returned string with Google Gson to map JSON to object of specified class, like this:

String data = getJSON("http://localhost/authmanager.php");
AuthMsg msg = new Gson().fromJson(data, AuthMsg.class);
System.out.println(msg);

There is a sample of AuthMsg class:

public class AuthMsg {
    private int code;
    private String message;

    public int getCode() {
        return code;
    }
    public void setCode(int code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
}

JSON returned by http://localhost/authmanager.php must look like this:

{"code":1,"message":"Logged in"}

Regards

Java HttpURLConnection Returns JSON

You can use Gson. Here is the code to help you:

Map<String, Object> jsonMap;  
Gson gson = new Gson();  
Type outputType = new TypeToken<Map<String, Object>>(){}.getType();  
jsonMap = gson.fromJson("here your string", outputType);

Now you know how to get from and put those in session. You need to include Gson library in classpath.

How to get JSON object using HttpURLConnection instead of Volley?

The url in JsonObjectRequest() is not optional, and the JSONObject parameter is used to post parameters with the request to the url.

From the documentation:
http://afzaln.com/volley/com/android/volley/toolbox/JsonObjectRequest.html

http://developer.android.com/training/volley/index.html

JsonObjectRequest

public JsonObjectRequest(int method,
String url,
JSONObject jsonRequest,
Response.Listener listener,
Response.ErrorListener errorListener) Creates a new request.

Parameters:

method - the HTTP method to use

url - URL to fetch the JSON from

jsonRequest - A JSONObject to post with the request. Null is allowed
and indicates no parameters will be posted along with request.

listener - Listener to receive the JSON response

errorListener - Error listener, or null to ignore errors.

Using HttpURLConnection:

http://developer.android.com/reference/java/net/HttpURLConnection.html

The code would be something like this:

 public class getData extends AsyncTask<String, String, String> {

        HttpURLConnection urlConnection;

        @Override
        protected String doInBackground(String... args) {

            StringBuilder result = new StringBuilder();

            try {
                URL url = new URL("https://api.github.com/users/dmnugent80/repos");
                urlConnection = (HttpURLConnection) url.openConnection();
                InputStream in = new BufferedInputStream(urlConnection.getInputStream());

                BufferedReader reader = new BufferedReader(new InputStreamReader(in));

                String line;
                while ((line = reader.readLine()) != null) {
                    result.append(line);
                }

            }catch( Exception e) {
                e.printStackTrace();
            }
            finally {
                urlConnection.disconnect();
            }

            return result.toString();
        }

        @Override
        protected void onPostExecute(String result) {

            //Do something with the JSON string

        }

    }

How to retrieve JSON from my method?

You should read from the InputStream:

JSONObject myData = new JSONObject(IOUtils.toString(connection.getInputStream(),
    connection.getContentEncoding());

IOUtilsis a class from the Apache Commons IO utility library.

How use GET request with web API for JSON response using HttpURLConnection?

Just use an AsyncTask subclass in order to do the network operation inside thedoInBackground() method override, which is run on a background thread. Then pass the result to the onPostExecute() method override, which is run on the UI thread.

Here is a simple Activity with an AsyncTask that does what you need:

public class TestActivity extends AppCompatActivity {

    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

        textView = (TextView) findViewById(R.id.textView);

        new NetworkConnect().execute();
    }

    class NetworkConnect extends AsyncTask<Void, Void, JSONObject> {

        private static final String JSON_URL = "http://ip.jsontest.com/";
        String charset = "UTF-8";
        HttpURLConnection conn;
        StringBuilder result;
        URL urlObj;

        @Override
        protected JSONObject doInBackground(Void... args) {

            JSONObject retObj = null;

            try {
                urlObj = new URL(JSON_URL);

                conn = (HttpURLConnection) urlObj.openConnection();
                conn.setDoOutput(false);
                conn.setRequestMethod("GET");
                conn.setRequestProperty("Accept-Charset", charset);
                conn.setConnectTimeout(15000);
                conn.connect();

                //Receive the response from the server
                InputStream in = new BufferedInputStream(conn.getInputStream());
                BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                result = new StringBuilder();
                String line;
                while ((line = reader.readLine()) != null) {
                    result.append(line);
                }

                Log.d("NetworkConnect", "result: " + result.toString());

                retObj = new JSONObject(result.toString());

            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return retObj;
        }

        @Override
        protected void onPostExecute(JSONObject json) {
            //Use JSON result to display in TextView
            if (json != null) {
                textView.setText(json.toString());
            }
        }
    }
}

Note: ensure that you have the INTERNET permission in the AndroidManifest.xml:

<uses-permission android:name="android.permission.INTERNET" />

get JSONObject from httpURLConnection and parsing into ArrayList

First problem which type would be the choice for doInBackground
function

JSON String as in post is JSONArray of JSONObject's instead of JSONObject. create JSONArray from result in doInBackground :

JSONArray jsonArray = new JSONArray(result.toString());

how to deliver the jsonObject to my function onPostExecute?

Instead of JSONObject return ArrayList of items.

how can I get the content of the jsonObject variable to my ArrayList?

Parse jsonArray to get all JSONObject's from it then get required value from each JSONObject and add it to listdata

ArrayList<String> listdata = new ArrayList<String>();
for(int n = 0; n < jsonArray.length(); n++)
{
    JSONObject object = jsonArray.getJSONObject(n);
    listdata.add(object.optString("nr")); 
}

return listdata;

Post Json data with HttpURLConnection to REST API server

This is how I send a POST

Let me know if you need any clarification.

public static String executePost(String targetURL, String requestJSON, String apikey) {
        HttpURLConnection connection = null;
        InputStream is = null;

        try {
            //Create connection
            URL url = new URL(targetURL);
            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/json");
            //TODO may be prod or preprod api key
            if (apikey.equals(Constants.APIKEY_PREPROD)) {
                connection.setRequestProperty("Authorization", Constants.APIKEY_PREPROD);
            }
            if (apikey.equals(Constants.APIKEY_PROD)){
                connection.setRequestProperty("Authorization", Constants.APIKEY_PROD);
            }
            connection.setRequestProperty("Content-Length", Integer.toString(requestJSON.getBytes().length));
            connection.setRequestProperty("Content-Language", "en-US");  
            connection.setUseCaches(false);
            connection.setDoOutput(true);

            //Send request
            System.out.println(requestJSON);
            DataOutputStream wr = new DataOutputStream (
            connection.getOutputStream());
            wr.writeBytes(requestJSON);
            wr.close();

            //Get Response  

            try {
                is = connection.getInputStream();
            } catch (IOException ioe) {
                if (connection instanceof HttpURLConnection) {
                    HttpURLConnection httpConn = (HttpURLConnection) connection;
                    int statusCode = httpConn.getResponseCode();
                    if (statusCode != 200) {
                        is = httpConn.getErrorStream();
                    }
                }
            }

            BufferedReader rd = new BufferedReader(new InputStreamReader(is));

            StringBuilder response = new StringBuilder(); // or StringBuffer if Java version 5+
            String line;
            while ((line = rd.readLine()) != null) {
                response.append(line);
                response.append('\r');
            }
            rd.close();
            return response.toString();
        } catch (Exception e) {

            e.printStackTrace();
            return null;

        } finally {
            if (connection != null) {
                connection.disconnect();
            }
        }
    }

---

Related Topics