ajax 返回值方法php

<?PHP
function msg_error($state,$msg) {
    if(!empty($_REQUEST['callback'])) {
        $callback = $_REQUEST['callback'];
        $callback = preg_replace(array('/</','/>/','/"/','/\'/','/\+/','/\\\\/','/\//'),array('&lt;','&gt;','',''),$callback);
    }
    $a = array(
        'state' => $state,'msg' => $msg,);
    $ret = json_encode($a);
    if(!empty($callback)) $ret = sprintf("%s(%s)",$callback,$ret);
    header("Content-type: application/json");
    echo $ret;
    exit;
}