php 获取远程文件的最后修改日期
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Get the last modified date of a remote file
提问by Mark Henry
I would like to get the last modified date of a remote file by means of curl. Does anyone know how to do that?
我想通过 curl 获取远程文件的最后修改日期。有谁知道这是怎么做到的吗？
采纳答案by Daniel Sorichetti
From php's article:
来自php 的文章：
<?php
// outputs e.g. somefile.txt was last modified: December 29 2002 22:16:23.
$filename = 'somefile.txt';
if (file_exists($filename)) {
echo "$filename was last modified: " . date ("F d Y H:i:s.", filemtime($filename));
}
?>
filemtime() is the key here. But I'm not sure if you can get the last modified date of a remotefile, since the server should send it to you... Maybe in the HTTP headers?
filemtime() 是这里的关键。但是我不确定您是否可以获得远程文件的最后修改日期，因为服务器应该将其发送给您...也许在 HTTP 标头中？
回答by Tom Haigh
You could probably do something like this using curl_getinfo():
您可能可以使用curl_getinfo()以下方法执行以下操作：
<?php
$curl = curl_init('http://www.example.com/filename.txt');
//don't fetch the actual page, you only want headers
curl_setopt($curl, CURLOPT_NOBODY, true);
//stop it from outputting stuff to stdout
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
// attempt to retrieve the modification date
curl_setopt($curl, CURLOPT_FILETIME, true);
$result = curl_exec($curl);
if ($result === false) {
die (curl_error($curl));
}
$timestamp = curl_getinfo($curl, CURLINFO_FILETIME);
if ($timestamp != -1) { //otherwise unknown
echo date("Y-m-d H:i:s", $timestamp); //etc
}
回答by h4kuna
In PHP you can use the native function get_headers():
在 PHP 中，您可以使用本机函数get_headers()：
<?php
$h = get_headers($url, 1);
$dt = NULL;
if (!($h || strstr($h[0], '200') === FALSE)) {
$dt = new \DateTime($h['Last-Modified']);//php 5.3
}
回答by Pons
Sometimes header come with different upper lower case, this should help:
有时标头带有不同的大写小写，这应该会有所帮助：
function remoteFileData($f) {
$h = get_headers($f, 1);
if (stristr($h[0], '200')) {
foreach($h as $k=>$v) {
if(strtolower(trim($k))=="last-modified") return $v;
}
}
}
回答by Patrick Glandien
You can activate receiving the headers of the reply with curl_setopt($handle, CURLOPT_HEADER, true). You can also turn on CURLOPT_NOBODY to only receive the headers, and after that explode the result by \r\n and interpret the single headers. The header Last-Modifiedis the one that you are interested in.
您可以使用 激活接收回复的标题curl_setopt($handle, CURLOPT_HEADER, true)。您还可以打开 CURLOPT_NOBODY 以仅接收标头，然后通过 \r\n 分解结果并解释单个标头。标题Last-Modified是您感兴趣的标题。
回答by trante
By editing h4kuna's answer I created this:
通过编辑 h4kuna 的答案，我创建了这个：
$fileURL='http://www.yahoo.com';
$headers = get_headers($fileURL, 1);
$date = "Error";
//echo "<pre>"; print_r($headers); echo "</pre>";
if ( $headers && (strpos($headers[0],'200') !== FALSE) ) {
$time=strtotime($headers['Last-Modified']);
$date=date("d-m-Y H:i:s", $time);
}
echo 'file: <a href="'.$fileURL.'" target="_blank">'.$fileURL.'</a> (Last-Modified: '.$date.')<br>';
回答by michalzuber
Had to solve similiar issue, but for me download once a day was enough so I compared just the modify day of the local (downloaded) cache file. The remote file had no Last-Modified header.
不得不解决类似的问题，但对我来说每天下载一次就足够了，所以我只比较了本地（下载的）缓存文件的修改日期。远程文件没有 Last-Modified 标头。
$xml = 'test.xml';
if (is_file($xml) || date('d', filemtime($xml)) != date('d')) {
$xml = file_get_contents(REMOTE_URL);
}
回答by dassouki
would something like this work, from web developer forum
像这样的工作，来自网络开发者论坛
<? $last_modified = filemtime("content.php"); print("Last Updated - ");
print(date("m/d/y", $last_modified)); ?
// OR
$last_modified = filemtime(__FILE__);
the link provides some useful insite on you can use them
该链接提供了一些有用的网站，您可以使用它们
