Notice: A session had already been started – ignoring session_start() in .. on line ..
session_start()不只调用超过一次的情况会出现此提示
解决方案如下：
1) 修改php.ini的的session.autostart为0
session.auto_start = 0
2) php代码中使用如下代码
if (!session_id()) session_start();
替换原来的
session_start();