为什么我的图像上传器可以在除Internet Explorer之外的所有浏览器上工作

我下面的脚本用于用户将个人资料图片上传到他们的帐户。如果他们想上传新的个人资料图片，它还会删除当前的个人资料照片。

在过去的几个月里，我一直在努力构建一个在所有浏览器上都能一直工作的图像上传表单。关于如何使我的上传脚本更加健壮，我有更广泛的问题，但特别是我有一个主要问题。

为什么此脚本不适用于Internet Explorer？通过Chrome、Firefox和Safari上传都很好。然而，当我使用IE上传图像时，它会因为文件类型不正确而被拒绝。

以下是我在试图解决这个问题的过程中所尝试/研究的内容。

1） 确保enctype="multipart/form-data"包含在我的html表单中

2） 尝试使用exif_imagetype($file)获取文件类型，而不是getimagesize()（注意：我还在php.ini文件中启用了exif_imagetype()）。我读到这是一种更可靠的确定文件类型的方法。此功能适用于其他三种浏览器，但是当使用IE时，它仍然无法确定文件类型。

3） 我使用var_dump($_FILES)来查看正在上传的内容。这显示了除IE之外的所有浏览器上的名称、大小、类型等。在IE上，似乎没有上传文件的名称。回显名称："string '' (length=0)"

html表单、图像上传脚本和图像调整大小脚本都位于下面。

形式：

<form method="post" enctype="multipart/form-data">
<input type="hidden" name="MAX_FILE_SIZE" value="625000"> 
<input type="file" class="span2" name="image" id="image" size="20">                        
<input name="picture" type="submit" value="update" class="btn btn-primary" style="margin-bottom: -10px"> 
</form>

上传脚本：

if (isset($_POST['picture'])){
 //THIS SECTION IS FOR UPLOADING THE PROFILE PICTURE. 
 //It will create a standard profile image size 320 by 320.
 //It also then creates a 'thumbnail' picture size 100 x 100

//delete the original profile image (if there was one)
$CurrentImage = getImage("profile",$id,FALSE);
$CurrentImageThumb = getImage("profile",$id,TRUE);
//if the current image is something other than the generic image, delete the current images
            if($CurrentImage!="images/profile/generic.jpg")unlink($CurrentImage);           if($CurrentImageThumb!="images/profile/genericthumb.jpg")unlink($CurrentImageThumb); 

//get the type of the upload            
$pic_type = ".".pathinfo($_FILES['image']['name'], PATHINFO_EXTENSION);
//save the initial file
$saveto = "images/profile/$id"."$pic_type";
move_uploaded_file($_FILES['image']['tmp_name'], $saveto);
//resize it and display the appropriate message if it works/doesn't work
//CREATE FULL SIZE
if (true === ($pic_error = image_resize($saveto,$saveto, 320, 320, 0))){
//CREATE THUMBNAIL
$saveto2 = "images/profile/$id"."thumb"."$pic_type";                
if (true === ($pic_error = image_resize($saveto,$saveto2, 100, 100, 0))){
showAlert(2,"Your image has been uploaded!"," If the image did not change, <a href='"./editprofile'">click here</a> to reload the page.");
}}else{
showAlert(3,"File Issue: ",$pic_error);
unlink($saveto);//delete the upload 
unlink($saveto2);//delete the upload    
}
}

图像调整大小脚本：

 function image_resize($src, $dst, $width, $height, $crop=0){
    //if getimagesize doesn't output an array with the first two values being width and height, we reject the file
    if(!list($w, $h) = getimagesize($src)) return "Unsupported file type. We only accept image files the extension .jpg, .jpeg, .png, .gif, or .bmp";
      //get the image type based on the file extension
      $type = strtolower(substr(strrchr($src,"."),1));
      //based on file type, create a new image from the url
      if($type == 'jpeg') $type = 'jpg';
      switch($type){
        case 'bmp': $img = imagecreatefromwbmp($src); break;
        case 'gif': $img = imagecreatefromgif($src); break;
        case 'jpg': $img = imagecreatefromjpeg($src); break;
        case 'png': $img = imagecreatefrompng($src); break;
        default : return "Unsupported file type. We only accept image files with the extension .jpg, .jpeg, .png, .gif, or .bmp";
      }

  // resize (get the dimensions for resize if $crop or not)
  if($crop){
    //if initial image is smaller than crop size display error
    if($w < $width or $h < $height) return "Picture is too small. Your image must be LARGER than ".$width."pixels by ".$height." pixels.";
    $ratio = max($width/$w, $height/$h);
    $h = $height / $ratio;
    $x = ($w - $width / $ratio) / 2;
    $w = $width / $ratio;
  }
  else{
    if($w < $width and $h < $height) return "Picture is too small. Your image must be LARGER than ".$width."pixels by ".$height." pixels.";
    $ratio = min($width/$w, $height/$h);
    $width = $w * $ratio;
    $height = $h * $ratio;
    $x = 0;
  }
  //create a new true color image
  $new = imagecreatetruecolor($width, $height);
  // preserve transparency
  if($type == "gif" or $type == "png"){
    imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
    imagealphablending($new, false);
    imagesavealpha($new, true);
  }
  //COPY AND RESIZE THE IMAGE
  /**imagecopyresampled ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , 
  int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )
  imagecopyresampled() will take an rectangular area from src_image of width src_w and height src_h at 
  position (src_x,src_y) and place it in a rectangular area of dst_image of width dst_w and height dst_h at position (dst_x,dst_y).
  */
  imagecopyresampled($new, $img, 0, 0, $x, 0, $width, $height, $w, $h);
  //then output the image to the file
  switch($type){
    case 'bmp': imagewbmp($new, $dst); break;
    case 'gif': imagegif($new, $dst); break;
    case 'jpg': imagejpeg($new, $dst); break;
    case 'png': imagepng($new, $dst); break;
  }
  return true;
}