如何阻止php脚本直接从地址栏执行？

Question

I have something like this:

$.getJSON('/scripts/commons/theScriptDoTravelBackInTime.php',{
}, function(){
  // etc.. etc...
}
});

Is there a way to stop the php script from being executed simply by a direct call in the address bar like http://www.myserver/scripts/commons/theScriptDoTravelBackInTime.php ?

Maybe outputting an echo "Hey no cheating !"

Answer 1

This is what the kohana framework uses:

   public static function is_ajax()
    {
      return (isset($_SERVER['HTTP_X_REQUESTED_WITH']) AND 
              strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) === 'xmlhttprequest');
    }