php判断文件上传图片格式的实例详解

 $type  = $_files['image']['tmp_name'];//文件名
 //$type  = $this->getimagetype( $type ); 
 $filetype = ['jpg', 'jpeg', 'gif', 'bmp', 'png'];
 if (! in_array($type, $filetype))
 { 
  return "不是图片类型";
 ｝

 //*判断图片上传格式是否为图片 return返回文件后缀
 public function getimagetype($filename)
 {
  $file = fopen($filename, 'rb');
  $bin = fread($file, 2); //只读2字节
  fclose($file);
  $strinfo = @unpack('c2chars', $bin);
  $typecode = intval($strinfo['chars1'].$strinfo['chars2']);
  // dd($typecode);
  $filetype = '';
  switch ($typecode) {
   case 255216:
    $filetype = 'jpg';
    break;
   case 7173:
    $filetype = 'gif';
    break;
   case 6677:
    $filetype = 'bmp';
    break;
   case 13780:
    $filetype = 'png';
    break;
   default:
    $filetype = '只能上传图片类型格式';
  }
  // if ($strinfo['chars1']=='-1' and $strinfo['chars2']=='-40' ) return 'jpg';
  // if ($strinfo['chars1']=='-119' and $strinfo['chars2']=='80' ) return 'png';
  return $filetype;
 }