Android http POST response

Question

My knowledge is very limited in android I am newBi, can anyone tell me how can I get the response and post of JSON that I am getting....If you have suggestion just edit my code and insert a comment , so that I can identify my missing methods. I can't analyse some posted related question , I already do my research but I can't perfect it. Correct me if my code is wrong or incomplete.

 public void httpConnection(HashMap<String, String> postDataParams) {

    HttpURLConnection httpcon;
    String url = "(url here...)";
    String result;
    try {

        httpcon = (HttpURLConnection) ((new URL(url).openConnection()));
        httpcon.setDoOutput(true);
        httpcon.setRequestProperty("Key", "Value");
        httpcon.setRequestProperty("action", "get_scoop");
        httpcon.setRequestMethod("POST");

        httpcon.connect();


        OutputStream os = httpcon.getOutputStream();
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
        writer.write(getPostDataString(postDataParams));
        writer.close();
        os.close();


        BufferedReader br = new BufferedReader(new InputStreamReader(httpcon.getInputStream(), "UTF-8"));

        String line = "";
        StringBuilder sb = new StringBuilder();

        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

        br.close();
        result = sb.toString();

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


}
private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException{
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for(Map.Entry<String, String> entry : params.entrySet()){
        if (first)
            first = false;
        else
            result.append("&");

        result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
        result.append("=");
        result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
    }

    return result.toString();
}

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

    public CallAPI() {
        //set context variables if required
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }


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

        String urlString = params[0]; // URL to call

        String resultToDisplay = "";

        InputStream in = null;
        try {

            URL url = new URL(urlString);

            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setReadTimeout(10000);
            urlConnection.setConnectTimeout(10000);
            urlConnection.setRequestMethod("POST");
            urlConnection.setDoInput(true);
            urlConnection.setDoOutput(true);


            in = new BufferedInputStream(urlConnection.getInputStream());


        } catch (Exception e) {

            Log.e("TAG", e.getMessage());


            return e.getMessage();

        }

        try {
                resultToDisplay = IOUtils.toString(in, "UTF-8");
            //to [convert][1] byte stream to a string
        } catch (IOException e) {
            e.printStackTrace();
        }
        return resultToDisplay;
    }


    @Override
    protected void onPostExecute(String result) {
        //Update the UI
    }
}

Answer 1

Simple example for fetching data via retrofit :

Note : this api runs in background thread hence do not call this method from any other background thread like asynctask

private void fetchDoctorClinics() {
        if (EasyPadhaiUtils.checkInternetConnection(DoctorDashbaord.this)) {

            // State Callback
            retrofit2.Callback callback = new retrofit2.Callback<ClinicsModel>() {
                @Override
                public void onResponse(Call<ClinicsModel> call, Response<ClinicsModel> response) {


                }

                @Override
                public void onFailure(Call<ClinicsModel> call, Throwable t) {

                }
            };

            Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(Constants.DOMAIN_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();

            // prepare call in Retrofit 2.0
            ClinicsInterface clinicsInterface = retrofit.create(ClinicsInterface.class);
            Call<ClinicsModel> call = clinicsInterface.getClinics("10");
            call.enqueue(callback);
        } else {
            // Network not available , handle this
        }
    }

and below is how you create post request via interface :

public interface ClinicsInterface {
    @FormUrlEncoded
    @POST(Constants.CONTROLLER_API)
    Call<ClinicsModel> getClinics(@Field(Constants.APPOINTMENT_DOCTOR_ID) String doctorId);
}

Do update your gradle with below retrofit lib :

    compile 'com.google.code.gson:gson:2.6.2'
    compile 'com.squareup.retrofit2:retrofit:2.1.0'
    compile 'com.squareup.retrofit2:converter-gson:2.1.0'