php 如何从url检查文件是否存在
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How to check if a file exists from a url
提问by David
I need to check if a particular file exists on a remote server. Using is_file()and file_exists()doesn't work. Any ideas how to do this quickly and easily?
我需要检查远程服务器上是否存在特定文件。使用is_file()和file_exists()不起作用。任何想法如何快速轻松地做到这一点？
回答by patrick
You don't need CURL for that... Too much overhead for just wanting to check if a file exists or not...
你不需要 CURL ......只是想检查文件是否存在太多开销......
Use PHP's get_header.
$headers=get_headers($url);
Then check if $result[0] contains 200 OK (which means the file is there)
然后检查 $result[0] 是否包含 200 OK （这意味着文件在那里）
A function to check if a URL works could be this:
检查 URL 是否有效的函数可能是这样的：
function UR_exists($url){
$headers=get_headers($url);
return stripos($headers[0],"200 OK")?true:false;
}
/* You can test a URL like this (sample) */
if(UR_exists("http://www.amazingjokes.com/"))
echo "This page exists";
else
echo "This page does not exist";
回答by Amila
You have to use CURL
你必须使用卷曲
function does_url_exists($url) {
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_exec($ch);
$code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
if ($code == 200) {
$status = true;
} else {
$status = false;
}
curl_close($ch);
return $status;
}
回答by Daniel Kossmann
I've just found this solution:
我刚刚找到了这个解决方案：
if(@getimagesize($remoteImageURL)){
//image exists!
}else{
//image does not exist.
}
Source: http://www.dreamincode.net/forums/topic/11197-checking-if-file-exists-on-remote-server/
来源：http: //www.dreamincode.net/forums/topic/11197-checking-if-file-exists-on-remote-server/
回答by Daniel de coder
Hi according to our test between 2 different servers the results are as follows:
您好，根据我们在 2 个不同服务器之间的测试，结果如下：
using curl for checking 10 .png files (each about 5 mb) was on average 5.7 secs. using header check for the same thing took average of 7.8 seconds!
使用 curl 检查 10 个 .png 文件（每个大约 5 mb）平均需要 5.7 秒。对同一件事使用标题检查平均需要 7.8 秒！
So in our test curl was much faster if you have to check larger files!
因此，在我们的测试中，如果您必须检查较大的文件，curl 会快得多！
our curl function is:
我们的 curl 函数是：
function remote_file_exists($url){
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if( $httpCode == 200 ){return true;}
return false;
}
here is our header check sample:
这是我们的标题检查示例：
function UR_exists($url){
$headers=get_headers($url);
return stripos($headers[0],"200 OK")?true:false;
}
回答by Tom
You can use the function file_get_contents();
您可以使用函数 file_get_contents();
if(file_get_contents('https://example.com/example.txt')) {
//File exists
}
回答by fivedigit
Do a request with curl and see if it returns a 404 status code. Do the request using the HEAD request method so it only returns the headers without a body.
使用 curl 发出请求，看看它是否返回 404 状态代码。使用 HEAD 请求方法执行请求，因此它只返回没有正文的标头。
回答by Андрей Рабой
$headers = get_headers((isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://" . $_SERVER[HTTP_HOST] . '/uploads/' . $MAIN['id'] . '.pdf');
$fileExist = (stripos($headers[0], "200 OK") ? true : false);
if ($fileExist) {
?>
<a class="button" href="/uploads/<?= $MAIN['id'] ?>.pdf" download>скачать</a>
<? }
?>
