<?= \common\widgets\Plupload::widget([
 'model'=>$model,
 'attribute'=>'cover_img',
 'url'=>'/file/upload',//處理文件上傳控制器
])?>

<?php
namespace common\widgets;
use backend\assets\UploadAsset;
use yii;
use yii\helpers\Html;
use yii\base\Exception;
class Plupload extends yii\bootstrap\Widget{
 public $model;
 public $attribute;
 public $name;
 public $url;
 private $_html;
 public function init(){
  parent::init();
 if(!$this->url){
 throw new Exception('url參數不能為空');
 }
  if(!$this->model){
   throw new Exception('model屬性不能為空');
  }
  if(!$this->attribute){
   throw new Exception('attribute屬性不能為空');
  }
 }
 public function run(){
  $model = $this->model;
  $attribute = $this->attribute;
  $path = $model->$attribute?$model->$attribute:"/images/noimage.gif";//顯示文章圖片或者默認圖片
  $this->_html.='<div class="form-group field-article-author" id="container">';
  $this->_html.=Html::activeLabel($model,$attribute);
  $this->_html.=Html::activeHiddenInput($model,$attribute,['id'=>'hidden_input','value'=>$path]);
  $this->_html .= '<div id="pickfiles" style="height:50px;min-width:50px;max-width: 300px;overflow: hidden;"><img height="50" src="'.$path.'" /></div>';
  $this->_html.='</div> ';
  UploadAsset::register($this->view);
 $this->view->registerJs(
 '$(function(){
    initCoverImageUploader("pickfiles","container","2mb","'.$this->url.'","'.Yii::$app->request->getCsrfToken().'");
   });'
 );
  return $this->_html;
 }
}

<?php
namespace backend\assets;
use yii\web\AssetBundle;
class UploadAsset extends AssetBundle
{
 public $basePath = '@webroot';
 public $baseUrl = '@web';
 public $css = [
 ];
 public $js = [
  'js/upload.js'
 ];
 public $depends = [
  'backend\assets\PluploadAsset',
 ];
}

function initCoverImageUploader(buttonId,contatinerId,maxFileSize,url,csrfToken){
 var uploader = new plupload.Uploader({
  runtimes : 'html5,flash,silverlight,html4',
  browse_button :buttonId, // you can pass an id...
  container: contatinerId, // ... or DOM Element itself
  url : url,
  flash_swf_url : '@vendor/moxiecode/plupload/js/Moxie.swf',
  silverlight_xap_url : '@vendor/moxiecode/plupload//js/Moxie.xap',
  filters : {
   max_file_size : maxFileSize,
   mime_types: [
    {title : "Image files", extensions : "jpg,gif,png"},
    {title : "Zip files", extensions : "zip"}
   ]
  },
  multipart_params:{
   '_csrf':csrfToken
  },
  init: {
   FilesAdded: function(up, files) {
    uploader.start();
   },
   UploadProgress: function(up, file) {
    $('#'+contatinerId+' p').text('已上傳:'+file.percent+'%');
   },
   FileUploaded:function (up, file, result) {
    result = $.parseJSON(result.response);
    if(result.code == 0){
     $('#'+buttonId).html('<img src="'+result.path+'" height="50" />');
     $('#hidden_input').val(result.path);
     //console.log(result.message);
    }
   },
   Error: function(up, err) {
    document.getElementById('console').appendChild(document.createTextNode("\nError #" + err.code + ": " + err.message));
   }
  }
 });
 uploader.init();
}

<?php
namespace backend\assets;
use yii\web\AssetBundle;
class PluploadAsset extends AssetBundle
{
 public $sourcePath = '@vendor/moxiecode/plupload';
 public $css = [
 ];
 public $js = [
  'js/plupload.full.min.js',
 ];
 public $depends = [
  'yii\web\JqueryAsset',
 ];
}

class FileController extends BaseController
{
 public function actionUpload(){
  Yii::$app->response->format=Response::FORMAT_JSON;
  $model = New ImageUpload();
  $model->fileInputName = 'file';
  if($model->save()){
   return ['code'=>0,'message'=>$model->getMessage(),'path'=>$model->getUrlPath()];
  }else{
   return ['code'=>1,'message'=>$model->getMessage()];
  }
 }
}

<?php
namespace common\models;
use yii\base\Exception;
use yii\helpers\FileHelper;
use yii\web\UploadedFile;
class ImageUpload extends \yii\base\Object
{
 public $fileInputName = 'file';//上傳表單 file name
 public $savePath ;//圖像保存根位置
 public $allowExt = ['jpg','png','jpeg','gif','bmp'];//允許上傳后綴
 public $maxFileSize=1024100000;//最大大小
 public $allowType = ['image/jpeg','image/bmp','image/gif','image/png','image/pjpeg','image/bmp','image/gif','image/x-png','image/pjpeg','image/bmp', 'image/gif' ,'image/x-png','image/pjpeg','image/bmp','image/gif','image/x-png'];
 private $_uploadFile;//上傳文件
 private $filePath;//文件路徑
 private $urlPath;//拜訪路徑
 private $res=false;//返回狀態
 private $message;//返回信息
 public function getMessage(){
  return $this->message;
 }
 public function getUrlPath(){
  return $this->urlPath;
 }
 public function init(){
  if(!$this->fileInputName) throw new Exception('fileInputName屬性不能為空');
  if(!$this->savePath) $this->savePath = \Yii::$app->basePath.'/web/uploads/images';
  $this->savePath = rtrim($this->savePath,'/');
  if(!file_exists($this->savePath)){
   if(! FileHelper::createDirectory($this->savePath)){
    $this->message = '沒有權限創建'.$this->savePath;
    return false;
   }
  }
  $this->_uploadFile = UploadedFile::getInstanceByName($this->fileInputName);
  if(!$this->_uploadFile){
   $this->message = '沒有找到上傳文件';
   return false;
  }
  if($this->_uploadFile->error){
   $this->message = '上傳失敗';
   return false;
  }
  if(!in_array($this->extension,$this->allowExt) || !in_array($this->type,$this->allowType)){
   $this->message = '該文件類型不允許上傳';
   return false;
  }
  if($this->_uploadFile->size> $this->maxFileSize){
   $this->message = '文件過大';
   return false;
  }
  $path = date('Y-m',time());
  if(!file_exists($this->savePath.'/'.$path)){
   FileHelper::createDirectory($this->savePath.'/'.$path);
  }
  $name = substr(\Yii::$app->security->generateRandomString(),-4,4);
  $this->filePath = $this->savePath.'/'.$path.'/'.$this->baseName.'--'.$name.'.'.$this->extension;
  $this->urlPath = '/uploads/images/'.$path.'/'.$this->baseName.'--'.$name.'.'.$this->extension;
 }
 public function save(){
  if($this->_uploadFile->saveAs($this->filePath)){
   $this->CreateThumbnail($this->filePath);//縮放圖片
   $this->res = true;
  }else{
   $this->res = false;
  }
  if($this->res){
   $this->message = $this->_uploadFile->baseName.'.'.$this->_uploadFile->extension.'上傳成功';
  }else{
   $this->message = $this->_uploadFile->baseName.'.'.$this->_uploadFile->extension.'上傳失敗';
  }
  return $this->res;
 }
 /**
  * 獲取文件名字
  * @return null
  */
 public function getBaseName(){
  if($this->_uploadFile){
   return $this->_uploadFile->baseName;
  }else{
   return null;
  }
 }
 /**
  * 返回文件后綴
  * @return null
  */
 public function getExtension(){
  if($this->_uploadFile){
   return $this->_uploadFile->extension;
  }else{
   return null;
  }
 }
 /**
  * 返回文件類型
  * @return mixed
  */
 public function getType(){
  if($this->_uploadFile){
   return $this->_uploadFile->type;
  }
  return null;
 }
 /**
  * 生成保持原圖縱橫比的縮略圖,支持.png .jpg .gif
  * 縮略圖類型統一為.png格式
  * $srcFile  原圖像文件名稱
  * $toFile  縮略圖文件名稱,為空覆蓋原圖像文件
  * $toW   縮略圖寬
  * $toH   縮略圖高
  * @return bool
  */
 public static function CreateThumbnail($srcFile, $toFile="", $toW=100, $toH=100)
 {
  if ($toFile == "") $toFile = $srcFile;
  $data = getimagesize($srcFile);//返回含有4個單元的數組,0-寬,1-高,2-圖像類型,3-寬高的文本描述.
  if (!$data) return false;
  //將文件載入到資源變量im中
  switch ($data[2]) //1-GIF,2-JPG,3-PNG
  {
   case 1:
    if(!function_exists("imagecreatefromgif")) return false;
    $im = imagecreatefromgif($srcFile);
    break;
   case 2:
    if(!function_exists("imagecreatefromjpeg")) return false;
    $im = imagecreatefromjpeg($srcFile);
    break;
   case 3:
    if(!function_exists("imagecreatefrompng")) return false;
    $im = imagecreatefrompng($srcFile);
    break;
  }
  //計算縮略圖的寬高
  $srcW = imagesx($im);
  $srcH = imagesy($im);
  $toWH = $toW / $toH;
  $srcWH = $srcW / $srcH;
  if ($toWH <= $srcWH) {
   $ftoW = $toW;
   $ftoH = (int)($ftoW * ($srcH / $srcW));
  } else {
   $ftoH = $toH;
   $ftoW = (int)($ftoH * ($srcW / $srcH));
  }
  if (function_exists("imagecreatetruecolor")) {
   $ni = imagecreatetruecolor($ftoW, $ftoH); //新建一個真彩色圖像
   if ($ni) {
    //重采樣拷貝部分圖像并調整大小 可保持較好的清晰度
    imagecopyresampled($ni, $im, 0, 0, 0, 0, $ftoW, $ftoH, $srcW, $srcH);
   } else {
    //拷貝部分圖像并調整大小
    $ni = imagecreate($ftoW, $ftoH);
    imagecopyresized($ni, $im, 0, 0, 0, 0, $ftoW, $ftoH, $srcW, $srcH);
   }
  } else {
   $ni = imagecreate($ftoW, $ftoH);
   imagecopyresized($ni, $im, 0, 0, 0, 0, $ftoW, $ftoH, $srcW, $srcH);
  }
  switch ($data[2]) //1-GIF,2-JPG,3-PNG
  {
   case 1:
    imagegif($ni, $toFile);
    break;
   case 2:
    imagejpeg($ni, $toFile);
    break;
   case 3:
    imagepng($ni, $toFile);
    break;
  }
  ImageDestroy($ni);
  ImageDestroy($im);
  return $toFile;
 }
}