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('<', '>', '', '', '', '', ''), $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;
}