PHP下载远程图片的3个方法

<?php

function dlfile1($file_url, $save_to)
{
$in = fopen($file_url, "rb");
$out = fopen($save_to, "wb");
while ($chunk = fread($in,8192))
{
fwrite($out, $chunk, 8192);
}
fclose($in);
fclose($out);
}

function dlfile_curl($file_url, $save_to)			// 不支持https
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_POST, 0);
curl_setopt($ch,CURLOPT_URL, $file_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$file_content = curl_exec($ch);
curl_close($ch);
if(!$file_content)
{
echo "download file failed";
return;
}

$downloaded_file = fopen($save_to, 'w');
fwrite($downloaded_file, $file_content);
fclose($downloaded_file);
}

function dlfile3($file_url, $save_to)
{
$content = file_get_contents($file_url);
file_put_contents($save_to, $content);
}

$url = "https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=gQFM8TwAAAAAAAAAAS5odHRwOi8vd2VpeGluLnFxLmNvbS9xLzAyM1lwVXBCRWNkQ20xNmV5TDFwMUQAAgSO1QdZAwQAjScA";

//$url = 'http://avatar.csdn.net/9/D/D/1_iefreer.jpg';

dlfile3($url, 'aaa.jpg');