How to call REST (POST) or GET webservice from Android

RESTful Web services: The basics

Representational State Transfer (REST) has gained widespread acceptance across the Web as a simpler alternative to SOAP- and Web Services Description Language (WSDL)-based Web services. Key evidence of this shift in interface design is the adoption of REST by mainstream Web 2.0 service providers—including Yahoo, Google, and Facebook—who have deprecated or passed on SOAP and WSDL-based interfaces in favor of an easier-to-use, resource-oriented model to expose their services. In this article, Alex Rodriguez introduces you to the basic principles of REST.
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for demo code-->https://github.com/Gaganjdeep/HitWebServicesLibG.git

Method to call a POST webservice without using HttpClient as it is deprecated:

it will return response in string

**pass data (params) using a HashMap ,as NameValuePair list is also deprecated**

  public String  performPostCall(String requestURL, HashMap<String,String> postDataParams) {

        URL url;
        String response = "";
        try {
            url = new URL(requestURL);

            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);


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

            writer.flush();
            writer.close();
            os.close();
            int responseCode=conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {
                String line;
                BufferedReader br=new BufferedReader(new InputStreamReader(conn.getInputStream()));
                while ((line=br.readLine()) != null) {
                    response+=line;
                }
            }
            else {
                response="";

                throw new Exception(responseCode+"");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return response;
    }

//Method to encode input params:

  private String getPostDataString(HashMap<String, String> params)

{

        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();

    }

Method to call a GET webservice :

   public String performGetCall(String url) throws Exception

    {

        URL obj = new URL(url);

        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // optional default is GET

        con.setRequestMethod("GET");

        //add request header

        int responseCode = con.getResponseCode();

        System.out.println("\nSending 'GET' request to URL : " + url);

        System.out.println("Response Code : " + responseCode);

        BufferedReader in = new BufferedReader(

                new InputStreamReader(con.getInputStream()));

        String inputLine;

        StringBuffer response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {

            response.append(inputLine);

        }

        in.close();

        //print result

        return response.toString(); //this is your response

    }