$img_file='http://www.somedomain.com/someimage.jpg'

$img_file=file_get_contents($img_file);

$file_loc=$_SERVER['DOCUMENT_ROOT'].'/some_dir/test.jpg';

$file_handler=fopen($file_loc,'w');

if(fwrite($file_handler,$img_file)==false){
    echo 'error';
}

fclose($file_handler);

$img_file='http://www.somedomain.com/someimage.jpg'

$img_file=file_get_contents($img_file);

$file_loc=$_SERVER['DOCUMENT_ROOT'].'/some_dir/test.jpg';

$file_handler=fopen($file_loc,'w');

if(fwrite($file_handler,$img_file)==false){
    echo 'error';
}

fclose($file_handler);

Vartec的cURL方案对我来说并不奏效。确实，由于我的特殊问题，它有了轻微的改进。

例如,

当服务器上有重定向(比如当你试图保存facebook的个人资料图像)，你将需要以下选项集:

curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

完整的解决方案是:

$ch = curl_init('http://example.com/image.php');
$fp = fopen('/my/folder/flower.gif', 'wb');
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_exec($ch);
curl_close($ch);
fclose($fp);

参见file()PHP手册:

$url    = 'http://mixednews.ru/wp-content/uploads/2011/10/0ed9320413f3ba172471860e77b15587.jpg';
$img    = 'miki.png';
$file   = file($url);
$result = file_put_contents($img, $file)

我不能得到任何其他解决方案的工作，但我能够使用wget:

$tempDir = '/download/file/here';
$finalDir = '/keep/file/here';
$imageUrl = 'http://www.example.com/image.jpg';

exec("cd $tempDir && wget --quiet $imageUrl");

if (!file_exists("$tempDir/image.jpg")) {
    throw new Exception('Failed while trying to download image');
}

if (rename("$tempDir/image.jpg", "$finalDir/new-image-name.jpg") === false) {
    throw new Exception('Failed while trying to move image file from temp dir to final dir');
}

$data = file_get_contents('http://example.com/image.php');
$img = imagecreatefromstring($data);
imagepng($img, 'test.png');