php - 上传 JPG 但不是 jpg

Question

我有一段代码可以上传图像并创建缩略图，只要扩展名是小写的 jpg，但如果是大写的 JPG，它就不会上传图像。当我重命名图像时，例如example.JPG 到 example.jpg，它会上传。但是 example.JPG 不会上传，我也没有收到任何错误。这对我来说没有任何意义。有人对此有解释吗？这是我的代码:

<?php
function createThumbnail($filename) {
  require 'config.php';

  if(preg_match('/[.](jpg)$/', $filename)) {
    $im = imagecreatefromjpeg($filename.$path_to_image_directory);
  } else if (preg_match('/[.](gif)$/', $filename)) {
    $im = imagecreatefromgif($path_to_image_directory . $filename);
  } else if (preg_match('/[.](png)$/', $filename)) {
    $im = imagecreatefrompng($path_to_image_directory . $filename);
  }

  $ox = imagesx($im);
  $oy = imagesy($im);

  $nx = $final_width_of_image;
  $ny = $final_height_of_image;

  $nm = imagecreatetruecolor($nx, $ny);

  imagecopyresampled($nm, $im, 0,0,0,0,$nx,$ny,$ox,$oy);

  if(!file_exists($path_to_thumbs_directory)) {
    if(!mkdir($path_to_thumbs_directory)) {
       die("There was a problem. Please try again!");
    } 
  }

  imagejpeg($nm, $path_to_thumbs_directory . $filename);
  $tn = '<img src="' . $path_to_thumbs_directory . $filename . '" alt="image" />';
  $tn .= '<br />Congratulations. Your file has been successfully uploaded, and a      thumbnail has been created.';
  echo $tn;
}
?>

配置文件:

<?php  
$final_width_of_image = 300;
$final_height_of_image = 300;
$path_to_image_directory = '';
$path_to_thumbs_directory = '-tn';
?>     

Answer 1

在此代码块中，您只允许小写文件扩展名:

if(preg_match('/[.](jpg)$/', $filename)) {
//--lowercase-only--^ 
    $im = imagecreatefromjpeg($filename.$path_to_image_directory);
}else if (preg_match('/[.](gif)$/', $filename)) {
    $im = imagecreatefromgif($path_to_image_directory . $filename);
} else if (preg_match('/[.](png)$/', $filename)) {
    $im = imagecreatefrompng($path_to_image_directory . $filename);
}

您可以通过放置 OR condition 来修复在正则表达式中:

if(preg_match('/[.](jpg|JPG)$/', $filename)) {
// -----uppercase-------^
    $im = imagecreatefromjpeg($filename.$path_to_image_directory);
}else if (preg_match('/[.](gif|GIF)$/', $filename)) {
    $im = imagecreatefromgif($path_to_image_directory . $filename);
} else if (preg_match('/[.](png|PNG)$/', $filename)) {
    $im = imagecreatefrompng($path_to_image_directory . $filename);
}

或者您可以使用 i 修饰符添加不区分大小写:

if(preg_match('/[.](jpg)$/i', $filename)) {
// -------modifier--------^ 
    $im = imagecreatefromjpeg($filename.$path_to_image_directory);
}else if (preg_match('/[.](gif)$/i', $filename)) {
    $im = imagecreatefromgif($path_to_image_directory . $filename);
} else if (preg_match('/[.](png)$/i', $filename)) {
    $im = imagecreatefrompng($path_to_image_directory . $filename);
}