PHP抓取远程图片

<?php
function getImage($url, $filename=""){
    if($url == ""){
        return false;
    }
    $ext = strrchr($url, ".");
    if($ext!=".gif" && $ext!=".jpg" && $ext!=".bmp" && $ext!=".png"){
        echo "格式不支持";
        return false;
    }
    if($filename == ""){
        $filename = time().$ext;
    }
    ob_start();
    readfile($url);
    $img = ob_get_contents();
    ob_end_clean();
    $size = strlen($img);
    $fp = fopen($filename, "a");
    fwrite($fp, $img);
    fclose($fp);
    return $filename;
}
$result = getImage("图片路径","图片名称");
if($result){
    echo '<img src="'.$result.'">';
}else{
    echo "抓取失败";
}
?>