php copy（）不使用特定的url链接

I want to copy an image from an another server, but it doesn't work and i don't know why. Here is my code:

if(copy('http://demo.swyp.fr/mod_traffiq/thumb/LQ1009C/LQ143559C/LQ157553C-71x100.jpg', 'zzz.jpg')) {
    echo "Copy success!";
}else{
    echo "Copy failed.";
}

It always returns failed.

You are using the copy function. Although this method works with both remote sources and destinations, you are encouraged to use the file_put/get_contents-methods (see documentation quote below).

$image = file_get_contents('http://demo.swyp.fr/mod_traffiq/thumb/LQ1009C/LQ143559C/LQ157553C-71x100.jpg');
file_put_contents('zzz.jpg', $image);

From the file_get_contents documentation:

file_get_contents() is the preferred way to read the contents of a file into a string. It will use memory mapping techniques if supported by your OS to enhance performance.

Also note:

A URL can be used as a filename with this function if the fopen wrappers have been enabled.

However, if fopen remote URL is not turned on in your settings, you might test with cURL:

$ch = curl_init('http://demo.swyp.fr/mod_traffiq/thumb/LQ1009C/LQ143559C/LQ157553C-71x100.jpg');
$fp = fopen('zzz.jpg', 'wb');
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch);
curl_close($ch);
fclose($fp); 

There could be other PHP settings (or server configurations) which disables all of these code snippets from running. If this does not work, then it is a matter of configuration issues instead.