yii实现图片上传

<?php Namespace frontendmodels;   use yiibaseModel; use yiiwebUploadedFile; use yiidbActiveRecord; use yiidbQuery;   class UploadForm extends ActiveRecord {     /**      * @var UploadedFile      */     public $t_img;     public $t_title;     public $t_content;     public function rules()     {         return [             [[&#39;t_img&#39;], &#39;file&#39;, &#39;skipOnEmpty&#39; => false, 'extensions' =&gt; 'png, jpg,bmp,jpeg'],         ];     }     public function attributeLabels()     {         return [             't_img'=&gt;'请上传文章图片',             'verifyCode' =&gt; '请在右面输入验证码',         ];     }         public function upload()     {         $imgName=time().rand(100,999).".".$this-&gt;t_img-&gt;extension;         if ($this-&gt;validate()) {             $this-&gt;t_img-&gt;saveAs('uploads/' .$imgName);             $path='uploads/' .$imgName;             return $path;         } else {             return false;         }     } }   ?&gt;

 $data=Yii::$app->request->post();             $data['t_addtime']=date('Y-m-d H:i:s');             $upload->t_img = UploadedFile::getInstance($upload, 't_img');             $path=$upload->upload();

<?php use yiiwidgetsActiveForm; use yiihelpersHtml; use yiihelpersUrl; ?>=Html::a('返回','?r=course/classspace&amp;c_id='.$c_id)?&gt; <?php  $form=ActiveForm::begin(     [         &#39;options&#39; => ['enctype' =&gt; 'multipart/form-data'],         'method'=&gt;'POST',     ] );?&gt;