将图片url下载到本地保存为文件

$url = "图片的url地址";
$openid ="文件名，可以自定义其他的";

$header = array("Connection: Keep-Alive", "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Pragma: no-cache", "Accept-Language: zh-Hans-CN,zh-Hans;q=0.8,en-US;q=0.5,en;q=0.3", "User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:29.0) Gecko/20100101 Firefox/29.0");
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER);
curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_ENCODING, 'gzip,deflate');

$content = curl_exec($ch);
$curlinfo = curl_getinfo($ch);
//关闭连接
curl_close($ch);

if ($curlinfo['http_code'] == 200) {
    if ($curlinfo['content_type'] == 'image/jpeg') {
        $exf = '.jpg';
    } else if ($curlinfo['content_type'] == 'image/png') {
        $exf = '.png';
    } else if ($curlinfo['content_type'] == 'image/gif') {
        $exf = '.gif';
    }
    //存放图片的路径及图片名称  *****这里注意 你的文件夹是否有创建文件的权限 chomd -R 777 mywenjian
    $filename = $openid . $exf;//这里默认是当前文件夹，可以加路径的 可以改为$filepath = '../'.$filename
    $filepath = "./images/head/".$filename;
    $res = file_put_contents($filepath, $content);//同样这里就可以改为$res = file_put_contents($filepath, $content);
}