我对PHP编码还很陌生，但我正在尝试做一些非常简单的事情。当我的网站上有人上传图片时，图片将被重命名为随机数字，并移动到我的目录"上传/"
在我下面的脚本中，一切都在进行，直到：
// Upload the file to your specified path.
if(move_uploaded_file($_FILES['userfile']['tmp_name'], $upload_path . $filename))
echo "Your file has been added. Redirecting in 3 seconds."; //it worked
else
echo "There was a problem uploading your file. Please try again later."; // It failed :(.
我已经定义了所有的变量。不确定这里出了什么问题。我应该为上传者发布我的整个脚本吗？
这是表格：
<form enctype="multipart/form-data" action="uploader.php" method="POST">
<p>
<input type="hidden" name="MAX_FILE_SIZE" value="1048576" />
Choose a file to upload:
<br>(Only .jpg, .png, & .gif are allowed. Max file size = 1MB)</br></p>
<input name="uploadedfile" type="file" />
<input type="submit" value="Upload File" />
</form>
这是我的"uploader.php"
<?php
header('Refresh: 3; URL=index.html');
$path = $_FILES['uploadedfile']['name'];
$ext = pathinfo($path, PATHINFO_EXTENSION);
//This line assigns a random number to a variable. You could also use a timestamp here if you prefer.
$ran = rand () ;
//This takes the random number (or timestamp) you generated and adds a . on the end, so it is ready of the file extension to be appended.
$ran2 = $ran.".";
//This assigns the subdirectory you want to save into... make sure it exists!
$target = "uploads/";
//This combines the directory, the random file name, and the extension
$target = $target . $ran2.$ext;
$ext = ".".$ext;
$upload_path = "uploads/";
$filename = $target;
$allowed_filetypes = array('.jpeg','.jpg','.gif','.bmp','.png'); // These will be the types of file that will pass the validation.
$max_filesize = 1048576; // Maximum filesize in BYTES (currently 0.5MB).
$filename = $_FILES['userfile']['name']; // Get the name of the file (including file extension).
// Check if the filetype is allowed, if not DIE and inform the user.
if(!in_array($ext,$allowed_filetypes))
die('The file you attempted to upload is not allowed.'.$ext);
// Now check the filesize, if it is too large then DIE and inform the user.
if(filesize($_FILES['userfile']['tmp_name']) > $max_filesize)
die('The file you attempted to upload is too large.');
// Check if we can upload to the specified path, if not DIE and inform the user.
if(!is_writable($upload_path))
die('You cannot upload to the specified directory, please CHMOD it to 777.');
// Upload the file to your specified path.
if(move_uploaded_file($_FILES['userfile']['tmp_name'], $upload_path . $filename))
echo "Your file has been added. Redirecting in 3 seconds."; //it worked
else
echo "There was a problem uploading your file. Please try again later."; // It failed :(.
?>
您正在将$filename重置为文件的原始名称，取消所有随机名称生成：
$filename = $target;
$allowed_filetypes = array('.jpeg','.jpg','.gif','.bmp','.png'); // These will be the types of file that will pass the validation.
$max_filesize = 1048576; // Maximum filesize in BYTES (currently 0.5MB).
// this line circumvents the random filename generation
$filename = $_FILES['userfile']['name']; // Get the name of the file (including file extension).
考虑到这一点，如果你上传两次相同名称的文件，我会看到上面的错误。只要去掉最后一行$filename = ....，看看你的错误是否消失了。
您试图将$_FILES['userfile']['tmp_name']移动到另一个目的地，但您的文件似乎存储在$_FILES['uploadedfile']['tmp_name']中（因为uploadedfile是表单中输入的文件名，您在脚本开始时正确检查了它）。
此外，我强烈建议分配所有变量，并在一个地方使用/修改它们，否则你会容易犯这种很难追踪的简单错误。
以下是我如何重新编写您的PHP代码，我认为它更清晰：
<?php
header('Refresh: 3; URL=index.html');
//check if file uploaded correctly to server
if ($_FILES['uploadedfile']['error'] != UPLOAD_ERR_OK)
die('Some error occurred on file upload');
$filename = $_FILES['uploadedfile']['name'];
$uploadedFile = $_FILES['uploadedfile']['tmp_name'];
$ext = '.' . pathinfo($filename , PATHINFO_EXTENSION);
$upload_path = "uploads/";
//prepare random filename
do {
$newName = md5(rand().rand().rand().microtime()) . $ext;
} while (file_exists($upload_path . $newName));
$allowed_filetypes = array('.jpeg','.jpg','.gif','.bmp','.png'); // These will be the types of file that will pass the validation.
$max_filesize = 1048576; // Maximum filesize in BYTES (currently 0.5MB).
// Check if the filetype is allowed, if not DIE and inform the user.
if(!in_array($ext,$allowed_filetypes))
die('The file you attempted to upload is not allowed.'.$ext);
// Now check the filesize, if it is too large then DIE and inform the user.
if(filesize($uploadedFile) > $max_filesize)
die('The file you attempted to upload is too large.');
// Check if we can upload to the specified path, if not DIE and inform the user.
if(!is_writable($upload_path))
die('You cannot upload to the specified directory, please CHMOD it to 777.');
// Upload the file to your specified path.
if(move_uploaded_file($uploadedFile, $upload_path . $newName))
echo "Your file has been added. Redirecting in 3 seconds."; //it worked
else
echo "There was a problem uploading your file. Please try again later."; // It failed
?>