controllers调用models报错 [ 2.0 版本 ]

Test.php

<?
namespace app\models;

use yii\db\ActiveRecord;

class Test extends ActiveRecord
{
	public static function tableName(){
		return "test";
	}
}

IndexController.php

<?php
namespace app\controllers;

use yii\web\Controller;
use app\models\Test;

class IndexController extends Controller
{
	public function actionIndex()
	{
		$model = new Test();
		$data = $model->find()->one();
		return $this->render("index",array("row"=>$data));
	}
}

为什么$model = new Test();报错

Unknown Class – yii\base\UnknownClassException
Unable to find 'app\models\Test' in file: D:\phpStudy\PHPTutorial\WWW\bs/models/Test.php. Namespace missing?