CakePHP中出现persistent is not writable等Warning的解决方法

　　在新部署CakePHP项目或者从SVN中重新Update项目的时候，有时候会出现下面的警告：

Warning (512): D:\xampp\htdocs\xxxx\app\tmp\cache\ is not writable [CORE\cake\libs\cache\file.php, line 281]
Warning (512): \persistent\ is not writable [CORE\cake\libs\cache\file.php, line 281]
Warning (512): \models\ is not writable [CORE\cake\libs\cache\file.php, line 281]
Warning (2): Cannot modify header information - headers already sent by (output started at D:\xampp\htdocs\xxxx\cake\libs\debugger.php:686) [APP\app_controller.php, line 52]

　　这是因为app下tmp文件丢失的原因，tmp文件夹中存放的是系统生成的临时文件，在导出系统的时候一般会忽略。解决的办法就新建tmp及其子文件夹，tmp的文件夹结构如下：