PHP:
<?php
//Unicode
header("Content-Type:text/html; charset=utf-8");
$a = $_GET['a'];
$b = $_GET['b'];
...
?>
Android
HttpClient httpclient = new DefaultHttpClient();
HttpGet get = new HttpGet("Your url");
try {
HttpResponse response = httpclient.execute(get);
HttpEntity entity = response.getEntity();
return EntityUtils.toString(entity, "UTF-8");
} catch (ClientProtocolException e) {
Log.d("error", e.getMessage());
e.printStackTrace();
} catch (IOException e) {
Log.d("error", e.getMessage());
e.printStackTrace();
}