I am newbie to android development. I am using android studio for developing an application. Things i have done

1. Created a DB with two tables in it in MySQL.
2. Created two separate api's for both GET and POST methods.
3. Successfully accessed both api's

What i have achieved for now

1. Able to GET data form the GET api.
2. Able to POST data using the POST api

What i have to do now

I want my api to publish online, i.e. I want to deploy my services into a server and access them. At this point i am able to deploy the services on the server and accessed them.

Now i want my services(api's) to be secured. For that i have searched many articles and found two ways.

1. Use yii framework. Someone told me to use it because it automatically secured the api's. But i don't know for sure whether it do or not.
2. Manually secure the api's

As for point 1 the framework will be helpful but it's new to me and it will take time to coop with it as i am already created the web services.

For point 2 i got some information

1. using HMAC_SHA1
2. DETECTING MOBILE DEVICES USING PHP

Both links seems to be good but link 1 doesn't gives me much info on that.

Obviously i want to secure my both api's

Now the code part

GET_DATA.php

require_once ('config.php');

$sql = "SELECT * FROM users";


$r = mysqli_query($con,$sql);

$result = array();

while($row = mysqli_fetch_array($r)){
array_push($result,array(
    'Id'=>$row['Id'],
    'Name'=>$row['Name']
));}

echo json_encode(array('users'=>$result));

POST_DATA.php

require_once ('config.php');

$return_arr = array();

$UserId=($_POST['UserId']);
$Latitude=($_POST['Latitude']);
$Longitude=($_POST['Longitude']);
$DateTime=($_POST['DateTime']);


$user_register_sql1 = "INSERT INTO `activity`(`Id`,`UserId`, `Latitude`,`Longitude`,`DateTime`) values (NULL,'".$UserId."','".$Latitude."','".$Longitude."','".$DateTime."')";
mysqli_query ($con,$user_register_sql1);
$row_array['errorcode1'] = 1;

I have a user class from which i am getting username and ID

JSONfunctions.java

This class is responsible for getting data from the api

 public static JSONObject getJSONfromURL(String url)
{

    String json = "";
    JSONObject jsonObject = null;
    try
    {
        HttpClient httpClientt = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(url);
        HttpResponse httpResponse = httpClientt.execute(httpGet);
        BufferedReader br = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent()));
        StringBuffer sb = new StringBuffer();
        String line = "";
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

        json = sb.toString();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try
    {
        jsonObject = new JSONObject(json);
    } catch (JSONException e) {
        e.printStackTrace();
    }

    return jsonObject;
}

PutUtility.Java

This class is responsible for POST method

public void setParam(String key, String value) {
    params.put(key, value);
}

public String postData(String Url) {

    StringBuilder sb = new StringBuilder();
    for (String key : params.keySet()) {
        String value = null;
        value = params.get(key);


        if (sb.length() > 0) {
            sb.append("&");
        }
        sb.append(key + "=" + value);
    }

    try {
        // Defined URL  where to send data

        URL url = new URL(Url);

        URLConnection conn = null;
        conn = url.openConnection();

        // Send POST data request
        httpConnection = (HttpURLConnection) conn;
        httpConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        httpConnection.setRequestMethod("POST");
        httpConnection.setDoInput(true);
        httpConnection.setDoOutput(true);
        OutputStreamWriter wr = null;

        wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(sb.toString());
        wr.flush();

        BufferedReader in = new BufferedReader(
                new InputStreamReader(httpConnection.getInputStream()));
        String inputLine;
        response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        try {
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    return response.toString();
}

MainActivity.java

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    _latitude = (TextView)findViewById(R.id.latitude);
    _longitude = (TextView)findViewById(R.id.longitude);
    btn_get_coordinates = (Button)findViewById(R.id.button);
    btn_save_data = (Button)findViewById(R.id.btn_save);   


    btn_save_data.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if(UserId.toString()== "" || Latitude.toString() == "" || Longitude.toString() == "" || DateTime.toString() == "")
            {
                Toast.makeText(getApplicationContext(), "Data Not Saved !!!! Please select appropriate data to save", Toast.LENGTH_SHORT).show();
            }


            new ServiceLogin().execute(UserId, Latitude, Longitude, DateTime);

        }
    });

    // Download JSON file AsyncTask
    new DownloadJSON().execute();
}
    // Download JSON file AsyncTask
private class DownloadJSON extends AsyncTask<Void, Void, Void>
{

   @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = new ProgressDialog(MainActivity.this);
        progressDialog.setMessage("Fetching Users....!");
        progressDialog.setCancelable(false);
        progressDialog.show();

    }

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

        // Locate the Users Class
        users = new ArrayList<Users>();

        // Create an array to populate the spinner
        userList = new ArrayList<String>();
        // http://10.0.2.2:8000/MobileApp/index.php
        //http://10.0.2.2:8000/app/web/users/
        //http://192.168.100.8:8000/app/web/users/
        // JSON file URL address
        jsonObject = JSONfunctions.getJSONfromURL("http://192.168.100.9:8000/MobileApp/GET_DATA.php");

        try
        {
            JSONObject jobj = new JSONObject(jsonObject.toString());
            // Locate the NodeList name
            jsonArray = jobj.getJSONArray("users");

            for(int i=0; i<jsonArray.length(); i++)
            {
                jsonObject = jsonArray.getJSONObject(i);

                Users user = new Users();

                user.setId(jsonObject.optString("Id"));
                user.setName(jsonObject.optString("Name"));
                users.add(user);

                userList.add(jsonObject.optString("Name"));

            }
        } catch (JSONException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }


        return null;
    }

    @Override
    protected void onPostExecute(Void args)
    {
        // Locate the spinner in activity_main.xml
        Spinner spinner = (Spinner)findViewById(R.id.spinner);

        // Spinner adapter
        spinner.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_spinner_dropdown_item, userList));

        // Spinner on item click listener

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {


            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

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

                // Set the text followed by the position

                textViewResult.setText("Hi " + users.get(position).getName() + " your ID is " + users.get(position).getId());
                UserId = String.valueOf(users.get(position).getId());
                progressDialog.dismiss();
                _latitude.setText("");
                _longitude.setText("");
                Latitude = null;
                Longitude= null;

            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                textViewResult.setText("");
            }
        });
    }


}

As i am newbie, so i don't know what to do in php script and what to do in my android code :(. It would be very helpful if anyone can guide me or give me a tutorial that i follow.

Any help would be highly appreciated.