/**
 * 七牛资源压缩
 * @param $packageName 打包后的资源名
 * @param Array $sourceArray 资源数组 
 * [
 *   [
 *     'key' => 'http://source.domain.cn/test1.ppt',
 *     'alias' => 'alias1.ppt',//别名 可空，空则为源文件名,如要创建文件夹则命名为 文件夹名/文件名
 *   ],
 *   [
 *     'key' => 'http://source.domain.cn/test2.ppt',
 *     'alias' => 'alias2.ppt'
 *   ],
 * ]
 */
public function compress(Array $sourceArray,$packageName,$callbackUrl='')
 {
   $bucket = $this->bucket_for_image;
   $fops = 'mkzip/2';
   foreach ($sourceArray as $k => $source) {
     $Base64EncodedURL = $this->base64_urlSafeEncode($source['key']);
     $Base64AliasEncodedURL = $this->base64_urlSafeEncode($source['alias']);
     $fops .= '/url/'.$Base64EncodedURL;
     if(!empty($source['alias'])){
       $fops .= '/alias/'.$Base64AliasEncodedURL;
     }
   }
   $fops .= '|saveas/'.$this->saveasEnocde($packageName); 
   $res = $this->persistentOps('test.txt',$bucket,$fops,$callbackUrl,false);
   echo $res;
 }