PHP アプリケーションの Ajax が文字化けを返した場合はどうすればよいですか?

iconv('utf-8','gb2312',$_POST['Data']);

function arrayRecursive(&$array, $function, $apply_to_keys_also = false)
 {
     static $recursive_counter = 0;
     if (++$recursive_counter > 1000) {
         die('possible deep recursion attack');
     }
     foreach ($array as $key => $value) {
         if (is_array($value)) {
             arrayRecursive($array[$key], $function, $apply_to_keys_also);
         } else {
             $array[$key] = $function($value);
         }
   
         if ($apply_to_keys_also && is_string($key)) {
             $new_key = $function($key);
             if ($new_key != $key) {
                 $array[$new_key] = $array[$key];
                 unset($array[$key]);
             }
         }
     }
     $recursive_counter--;
 }
 function JSON($array) {
     arrayRecursive($array, 'urlencode', true);
     $json = json_encode($array);
     return urldecode($json);
 }
$json_string=JSON($data);
//$obj = json_decode($json_string);
print_r($json_string);