JSON between Android and PHP

Introduction

You are creating an Android app and want to read data from a MySQL database and send data. We will create a Web Service in PHP, read from the MySQL database, and let the Android connect with the Web Service and send data, and the Web Service will save it and another Web Service will read data from MySQL and send it to the Android app.

Using the code

First we have to create the Web service to read data from the MySQL database.

<?php  
<pre>/* require the user as the parameter */
<pre>//http://localhost:8080/sample1/webservice1.php?user=1
if(isset($_GET['user']) && intval($_GET['user'])) {
  /* soak in the passed variable or set our own */
  $number_of_posts = isset($_GET['num']) ? intval($_GET['num']) : 10; //10 is the default
  $format = strtolower($_GET['format']) == 'json' ? 'json' : 'xml'; //xml is the default
  $user_id = intval($_GET['user']); //no default
  /* connect to the db */
  $link = mysql_connect('localhost','root','123456') or die('Cannot connect to the DB');
  mysql_select_db('TEST',$link) or die('Cannot select the DB');
  /* grab the posts from the db */
  //$query = "SELECT post_title, guid FROM wp_posts WHERE post_author = 
  //  $user_id AND post_status = 'publish' ORDER BY ID DESC LIMIT $number_of_posts";
  $query = "SELECT * FROM `test`.`users`;";
  $result = mysql_query($query,$link) or die('Errant query:  '.$query);
  /* create one master array of the records */
  $posts = array();
  if(mysql_num_rows($result)) {
    while($post = mysql_fetch_assoc($result)) {
      $posts[] = array('post'=>$post);
    }
  }
  /* output in necessary format */
  if($format == 'json') {
    header('Content-type: application/json');
    echo json_encode(array('posts'=>$posts));
  }
  else {
    header('Content-type: text/xml');
    echo '';
    foreach($posts as $index => $post) {
      if(is_array($post)) {
        foreach($post as $key => $value) {
          echo '<',$key,'>';
          if(is_array($value)) {
            foreach($value as $tag => $val) {
              echo '<',$tag,'>',htmlentities($val),'</',$tag,'>';
            }
          }
          echo '</',$key,'>';
        }
      }
    }
    echo '';
  }
  /* disconnect from the db */
  @mysql_close($link);
}
?>

Here is the code for the Android activity to read from the Web Service and parse the JSON object:

public void clickbutton(View v) {
    try {
        // http://androidarabia.net/quran4android/phpserver/connecttoserver.php

        // Log.i(getClass().getSimpleName(), "send  task - start");
        HttpParams httpParams = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParams,
                TIMEOUT_MILLISEC);
        HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT_MILLISEC);
        //
        HttpParams p = new BasicHttpParams();
        // p.setParameter("name", pvo.getName());
        p.setParameter("user", "1");

        // Instantiate an HttpClient
        HttpClient httpclient = new DefaultHttpClient(p);
        String url = "http://10.0.2.2:8080/sample1/" + 
                     "webservice1.php?user=1&format=json";
        HttpPost httppost = new HttpPost(url);

        // Instantiate a GET HTTP method
        try {
            Log.i(getClass().getSimpleName(), "send  task - start");
            //
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
                    2);
            nameValuePairs.add(new BasicNameValuePair("user", "1"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String responseBody = httpclient.execute(httppost,
                    responseHandler);
            // Parse
            JSONObject json = new JSONObject(responseBody);
            JSONArray jArray = json.getJSONArray("posts");
            ArrayList<HashMap<String, String>> mylist = 
                   new ArrayList<HashMap<String, String>>();

            for (int i = 0; i < jArray.length(); i++) {
                HashMap<String, String> map = new HashMap<String, String>();
                JSONObject e = jArray.getJSONObject(i);
                String s = e.getString("post");
                JSONObject jObject = new JSONObject(s);

                map.put("idusers", jObject.getString("idusers"));
                map.put("UserName", jObject.getString("UserName"));
                map.put("FullName", jObject.getString("FullName"));

                mylist.add(map);
            }
            Toast.makeText(this, responseBody, Toast.LENGTH_LONG).show();

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // Log.i(getClass().getSimpleName(), "send  task - end");

    } catch (Throwable t) {
        Toast.makeText(this, "Request failed: " + t.toString(),
                Toast.LENGTH_LONG).show();
    }
}

Here is the PHP code to send data to the Web Service and save it:

<?php  
//$json=$_GET ['json'];
$json = file_get_contents('php://input');
$obj = json_decode($json);
//echo $json;

//Save
$con = mysql_connect('localhost','root','123456') 
       or die('Cannot connect to the DB');
mysql_select_db('TEST',$con);
  /* grab the posts from the db */
  //$query = "SELECT post_title, guid FROM wp_posts WHERE 
  //  post_author = $user_id AND post_status = 'publish'
  // ORDER BY ID DESC LIMIT $number_of_posts";
mysql_query("INSERT INTO `test`.`users` (UserName, FullName)
VALUES ('".$obj->{'UserName'}."', '".$obj->{'FullName'}."')");
mysql_close($con);
//
  //$posts = array($json);
  $posts = array(1);
    header('Content-type: application/json');
    echo json_encode(array('posts'=>$posts)); 
  ?>

Android activity to send data to the Web Service as a JSON object to save in the MySQL database:

public void clickbuttonRecieve(View v) {
    try {
        JSONObject json = new JSONObject();
        json.put("UserName", "test2");
        json.put("FullName", "1234567");
        HttpParams httpParams = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParams,
                TIMEOUT_MILLISEC);
        HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT_MILLISEC);
        HttpClient client = new DefaultHttpClient(httpParams);
        //
        //String url = "http://10.0.2.2:8080/sample1/webservice2.php?" + 
        //             "json={\"UserName\":1,\"FullName\":2}";
        String url = "http://10.0.2.2:8080/sample1/webservice2.php";

        HttpPost request = new HttpPost(url);
        request.setEntity(new ByteArrayEntity(json.toString().getBytes(
                "UTF8")));
        request.setHeader("json", json.toString());
        HttpResponse response = client.execute(request);
        HttpEntity entity = response.getEntity();
        // If the response does not enclose an entity, there is no need
        if (entity != null) {
            InputStream instream = entity.getContent();

            String result = RestClient.convertStreamToString(instream);
            Log.i("Read from server", result);
            Toast.makeText(this,  result,
                    Toast.LENGTH_LONG).show();
        }
    } catch (Throwable t) {
        Toast.makeText(this, "Request failed: " + t.toString(),
                Toast.LENGTH_LONG).show();
    }
}