Android - POST to RESTful Web Service

Question

I am looking for some guidance on how to post data to a web service in my Android application. Unfortunately this is a school project, so I'm not able to use external libraries.

The web service has a base URL, for example:

http://example.com/service/create

And takes two variables, in the following format:

username = "user1"
locationname = "location1"

The web service is RESTful and uses an XML structure, if that makes a difference. From my research I understand I should be using URLconnection rather than the deprecated HTTPconnection, but I cannot find an example of what I am looking for.

Here is my attempt, which is currently not working:

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toPost test = new toPost();
        text.execute();
    }

    private class toPost extends AsyncTask<URL, Void, String> {
        @Override
        protected String doInBackground(URL... params) {
            HttpURLConnection conn = null;
            try {
                URL url = new URL("http://example.com/service");
                conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
                String body = "username=user1&locationname=location1";
                OutputStream output = new BufferedOutputStream(conn.getOutputStream());
                output.write(body.getBytes());
                output.flush();
            } catch (ProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                conn.disconnect();
            }
            return null;
        }
    }

}

Have you tried looking into Retrofit instead of rolling your own HttpUrlConnection? — IgorGanapolsky, Nov 19 '15 at 16:14
Unfortunately this is a school project, so I'm not able to use external libraries — , Nov 19 '15 at 16:16

score 2 · Answer 1 · answered Nov 19 '15 at 16:27

I would use the volley library, as suggested by google

Making a request is explained on that page, but is as simple as:

final TextView mTextView = (TextView) findViewById(R.id.text);
...

// Instantiate the RequestQueue.
RequestQueue queue = Volley.newRequestQueue(this);
String url ="http://www.google.com";

// Request a string response from the provided URL.
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
            new Response.Listener<String>() {
    @Override
    public void onResponse(String response) {
        // Display the first 500 characters of the response string.
        mTextView.setText("Response is: "+ response.substring(0,500));
    }
}, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
        mTextView.setText("That didn't work!");
    }
});
// Add the request to the RequestQueue.
queue.add(stringRequest);

Unfortunately I'm not able to use any external libraries for this application — , Nov 19 '15 at 18:28
why not? you can just import it straight from google and ship it with your apk, I don't see what the issue would be? — Nanne, Nov 19 '15 at 20:50

score 2 · Answer 2 · answered Nov 21 '15 at 08:31

If you want to use HttpUrlConnection, you can refer to the following two samples. Hope this helps!

private class LoginRequest extends AsyncTask<Void, Void, String> {

    @Override
    protected String doInBackground(Void... voids) {
        String address = "http://server/login";
        HttpURLConnection urlConnection;
        String requestBody;
        Uri.Builder builder = new Uri.Builder();
        Map<String, String> params = new HashMap<>();            
        params.put("username", "bnk");
        params.put("password", "bnk123");

        // encode parameters
        Iterator entries = params.entrySet().iterator();
        while (entries.hasNext()) {
            Map.Entry entry = (Map.Entry) entries.next();
            builder.appendQueryParameter(entry.getKey().toString(), entry.getValue().toString());
            entries.remove();
        }
        requestBody = builder.build().getEncodedQuery();

        try {
            URL url = new URL(address);
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setDoOutput(true);
            urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            OutputStream outputStream = new BufferedOutputStream(urlConnection.getOutputStream());
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "utf-8"));
            writer.write(requestBody);
            writer.flush();
            writer.close();
            outputStream.close();

            JSONObject jsonObject = new JSONObject();
            InputStream inputStream;
            // get stream
            if (urlConnection.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
                inputStream = urlConnection.getInputStream();
            } else {
                inputStream = urlConnection.getErrorStream();
            }
            // parse stream
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String temp, response = "";
            while ((temp = bufferedReader.readLine()) != null) {
                response += temp;
            }
            // put into JSONObject
            jsonObject.put("Content", response);
            jsonObject.put("Message", urlConnection.getResponseMessage());
            jsonObject.put("Length", urlConnection.getContentLength());
            jsonObject.put("Type", urlConnection.getContentType());

            return jsonObject.toString();
        } catch (IOException | JSONException e) {
            return e.toString();
        }
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        Log.i(LOG_TAG, "POST\n" + result);
    }
}


private class JsonPostRequest extends AsyncTask<Void, Void, String> {

    @Override
    protected String doInBackground(Void... voids) {
        try {
            String address = "http://server/postvalue";
            JSONObject json = new JSONObject();                
            json.put("Title", "Dummy Title");
            json.put("Author", "Dummy Author");
            String requestBody = json.toString();
            URL url = new URL(address);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setDoOutput(true);
            urlConnection.setRequestProperty("Content-Type", "application/json");
            OutputStream outputStream = new BufferedOutputStream(urlConnection.getOutputStream());
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "utf-8"));
            writer.write(requestBody);
            writer.flush();
            writer.close();
            outputStream.close();

            InputStream inputStream;
            // get stream
            if (urlConnection.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
                inputStream = urlConnection.getInputStream();
            } else {
                inputStream = urlConnection.getErrorStream();
            }
            // parse stream
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String temp, response = "";
            while ((temp = bufferedReader.readLine()) != null) {
                response += temp;
            }
            // put into JSONObject
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("Content", response);
            jsonObject.put("Message", urlConnection.getResponseMessage());
            jsonObject.put("Length", urlConnection.getContentLength());
            jsonObject.put("Type", urlConnection.getContentType());
            return jsonObject.toString();
        } catch (IOException | JSONException e) {
            return e.toString();
        }
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        Log.i(LOG_TAG, "POST RESPONSE: " + result);
        mTextView.setText(result);
    }
}

score 1 · Answer 3 · answered Nov 19 '15 at 16:20

My suggestion is to use Retrofit among with Jackson converter.

Retrofit supports both asynchronous and synchronous requests. It supports GET, POST, PUT, DELETE, and HEAD methods.

Jackson will help you to parse XML to JSON object.

Both of these are very easy to use and have good documentation.

Here you can find simple tutorial for using Retrofit.

score 1 · Answer 4 · answered Jul 18 '16 at 08:59

Use below code to call rest web service from your android app. this is fully tested code.

public class RestClient {

    static Context context;
    private static int responseCode;
    private static String response;

    public static String getResponse() {
        return response;
    }

    public static void setResponse(String response) {
        RestClient.response = response;
    }

    public static int getResponseCode() {
        return responseCode;
    }

    public static void setResponseCode(int responseCode) {
        RestClient.responseCode = responseCode;
    }

    public static void Execute(String requestMethod, String jsonData, String urlMethod, Context contextTemp, HashMap<String, Object> params) {
        try {
            context = contextTemp;
            String ip = context.getResources().getString(R.string.ip);
            StringBuilder urlString = new StringBuilder(ip + urlMethod);
            if (params != null) {
                for (Map.Entry<String, Object> para : params.entrySet()) {
                    if (para.getValue() instanceof Long) {
                        urlString.append("?" + para.getKey() + "=" +(Long)para.getValue());
                    }
                    if (para.getValue() instanceof String) {
                        urlString.append("?" + para.getKey() + "=" +String.valueOf(para.getValue()));
                    }
                }
            }

            URL url = new URL(urlString.toString());

            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod(requestMethod);
            conn.setReadTimeout(10000 /*milliseconds*/);
            conn.setConnectTimeout(15000 /* milliseconds */);


            switch (requestMethod) {
                case "POST" : case "PUT":
                    conn.setDoInput(true);
                    conn.setDoOutput(true);
                    conn.setRequestProperty("Content-Type", "application/json;charset=utf-8");
                    conn.setRequestProperty("X-Requested-With", "XMLHttpRequest");
                    conn.connect();
                    OutputStream os = new BufferedOutputStream(conn.getOutputStream());
                    os.write(jsonData.getBytes());
                    os.flush();
                    responseCode = conn.getResponseCode();
                    break;
                case "GET":
                    responseCode = conn.getResponseCode();
                    System.out.println("GET Response Code :: " + responseCode);
                    break;
                 break;

            }
            if (responseCode == HttpURLConnection.HTTP_OK) { // success
                BufferedReader in = new BufferedReader(new InputStreamReader(
                        conn.getInputStream()));
                String inputLine;
                StringBuffer tempResponse = new StringBuffer();

                while ((inputLine = in.readLine()) != null) {
                    tempResponse.append(inputLine);
                }
                in.close();
                response = tempResponse.toString();
                System.out.println(response.toString());
            } else {
                System.out.println("GET request not worked");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


}

score 0 · Answer 5 · edited May 23 '17 at 12:17

0

Yes, you should use URLConnection for making requests.

You can send xml data as a payload.

Please refer Android - Using HttpURLConnection to POST XML data

    URL url = new URL(url);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    try {
        conn.setReadTimeout(10000);
        conn.setConnectTimeout(15000);
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);
        String body = "<xml...</xml>";
        OutputStream output = new BufferedOutputStream(conn.getOutputStream());
        output.write(body.getBytes());
        output.flush();
    } finally {
        conn.disconnect();
    }

edited May 23 '17 at 12:17

Community

1
1

answered Nov 17 '15 at 00:08

Jayesh

51
5

I've updated my post to include an attempt at getting this to work, however nothing is happening. Could you take a look? – Nov 17 '15 at 01:13
You need to call test.execute(); so that AsyncTask can execute your request. Also don't forget to add permissions to access internet in the manifest file – Jayesh Nov 17 '15 at 23:46
I have the correct permissions in manifest and added the execute, but its still not working – Nov 19 '15 at 16:08

score 0 · Answer 6 · answered Nov 26 '15 at 11:12

You would have to commit the request. This can be done by calling getResponseCode(), or getResponseMessage()) or getInputStream() for the response to be returned and processed.

Working code for your example:

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toPost test = new toPost();
        test.execute();
    }

    private class toPost extends AsyncTask<URL, Void, String> {
        @Override
        protected String doInBackground(URL... params) {
            HttpURLConnection conn = null;
            try {
                URL url = new URL("http://example.com/service");
                conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
                String body = "username=user1&locationname=location1";
                OutputStream output = new BufferedOutputStream(conn.getOutputStream());
                output.write(body.getBytes());
                output.flush();

                //This is needed
                // Could alternatively use conn.getResponseMessage() or conn.getInputStream()
                conn.getResponseCode();

            } catch (ProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                conn.disconnect();
            }
            return null;
        }
    }
}

score 0 · Answer 7 · answered Nov 26 '15 at 11:18

try this. (msg is the xml string )

 try
      {
        URL url = new URL(address);
        URLConnection uc = url.openConnection();
        HttpURLConnection conn = (HttpURLConnection) uc;
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-type", "text/xml");        
        PrintWriter pw = new PrintWriter(conn.getOutputStream());
        pw.write(msg.getText());
        pw.close();
        BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());
        bis.close();

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

Android - POST to RESTful Web Service

7 Answers7

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