<?php
/**
 * Created by PhpStorm.
 * Date: 2016/5/27
 * Time: 14:16
 */
namespace frontend\libs;
use Yii;
use yii\base\Action;
use yii\base\ActionFilter;
class FilterTest extends ActionFilter{
  //在action之前運行，可用來過濾輸入
  public function beforeAction($action) {
    echo '在調用action前顯示<br/>';
    return TRUE;//如果返回值為false,則action不會運行
  }
  //在action之后運行，可用來過濾輸出
  public function afterAction($action, $result) {
    return $result.'在調用action后顯示<br/>';//可以對action輸出的$result進行過濾，retun的內容會直接顯示
  }
}

<?php
/**
 * Created by PhpStorm.
 * Date: 2016/5/27
 * Time: 14:19
 */
 namespace frontend\controllers;
 use yii\web\controller;
class TestbehaviorController extends Controller{
  public function behaviors(){
    return [
      'test'=>[
       'class'=>'frontend\libs\FilterTest',//調用過濾器
      ],
    ];
  }
  public function actionFilter(){
    return "當前action顯示<br/>";//返回的內容會遞交給過濾器，由afterAction處理
  }
}