Yii控制器中filter过滤器用法分析

public function filters(){  return array(    'accessControl', // perform access control for CRUD operations    'postOnly + delete', // we only allow deletion via POST request    'projectContext +create index admin',  );}

public function filterProjectContext($filterChain){  $prijectId = null;  if(isset($_POST['pid'])){    $projectId = $_POST['pid'];  }elseif(isset($_GET['pid'])){    $projectId = $_GET['pid'];  }  $this->loadProject($projectId);  $filterChain->run();}public function loadProject($projectid){  if($this->_project === null){    $this->_project = Project::model()->findbyPK($projectid);    if($this->_project === null){      throw new CHttpException(404,'请求和项目没找到！');    }  }  return $this->_project;}