/**
* APP组件
* 单例模式
*
* @return F_Core_App
*/
public static function app()
{
if (Flow::$_app == null) {
//初始化基础APP
if (PHP_SAPI === "cli") {
Flow::$_app = new F_Cli_App();
} else {
Flow::$_app = new F_Web_App();
}
Flow::$_app->init();
}
return Flow::$_app;
}