设置cookie的域，实现共享session.php

$currentCookieParams = session_get_cookie_params();
$rootDomain = '.shixi.com';
session_set_cookie_params(
    $currentCookieParams["lifetime"],
    $currentCookieParams["path"],
    $rootDomain,
    $currentCookieParams["secure"],
    $currentCookieParams["httponly"]
);