PHP下载远程文件到本地存储的方法

<?phpfunction GrabImage($url,$filename="") {  if($url=="") return false;  if($filename=="") {    $ext=strrchr($url,".");    if($ext!=".gif" && $ext!=".jpg") return false;    $filename=date("dMYHis").$ext;  }  ob_start();  readfile($url);  $img = ob_get_contents();  ob_end_clean();  $size = strlen($img);  $fp2=@fopen($filename, "a");  fwrite($fp2,$img);  fclose($fp2);  return $filename;}function gethttpimage($url){   if(!empty($url)){     $filename=uniqid().strrchr($url,".");     echo $filename;    $get_file=@file_get_contents($url);     if($get_file){       $fp=@fopen($filename,"w");       @fwrite($fp,$get_file);       @fclose($fp);     }     return $imgUrl;   }else{     return false;   } } //$img=GrabImage("//www.VeVB.COm/images/logo.gif","");$img=gethttpimage("//www.VeVB.COm/images/logo.gif","");if($img) echo '<pre><img src="'.$img.'"></pre>';else echo "false";?>