PHP uses the Get_headers function to determine if a remote file exists _php

This example describes how PHP uses the Get_headers function to determine whether a remote file exists. Share to everyone for your reference. The implementation method is as follows:

Before the process about PHP to determine whether remote files exist in the article is the use of Fopen,sockt,curl function to check whether remote files exist, the following I introduce the use of get_headers to check whether remote files exist, interested friends can refer to.

Let's take a quick look at the get_headers () function

Get_headers () returns an array m containing the headers sent by the server in response to an HTTP request.

Get_headers: The sending server responds to HTTP requests

Get_headers (string url[link format])

Get_headers () returns the server HTTP request as an array m if execution fails, it will return false and an error level e_warning,

The optional parameter is set to 1,get_headers () to analyze the system's response speed and the keys in the set array.

The code is as follows:

<?php
$url = ' http://www.bitsCN.com ';
Print_r (Get_headers ($url));
Print_r (Get_headers ($url, 1));
?>

The results of the operation are as follows:

The code is as follows:

Array
(
[0] = = http/1.1-OK
[1] = cache-control:max-age=1800
[2] = content-length:54874
[3] = content-type:text/html
[4] = content-location:http://www.bitscn.com/index.htm
[5] = Last-modified:fri, 03:34:56 GMT
[6] = Accept-ranges:bytes
[7] = ETag: "B66ba847bcad01:bc5"
[8] = server:microsoft-iis/6.0
[9] = Date:fri, 03:37:34 GMT
[Ten] = Connection:close
)
Array
(
[0] = = http/1.1-OK
[Cache-control] = max-age=1800
[Content-length] = 54874
[Content-type] = text/html
[Content-location] = http://www.bitsCN.com/index.htm
[Last-modified] = Fri, 03:34:56 GMT
[Accept-ranges] = bytes
[ETag] = "B66ba847bcad01:bc5"
[Server] = microsoft-iis/6.0
[Date] = Fri, 03:37:35 GMT
[Connection] = Close
)

Determine if the remote file has the following code:

The code is as follows:

Determine if a remote file exists
function Remote_file_exists ($url) {
$executeTime = Ini_get (' max_execution_time ');
Ini_set (' Max_execution_time ', 0);
$headers = @get_headers ($url);
Ini_set (' Max_execution_time ', $executeTime);
if ($headers) {
$head = Explode ("', $headers [0]);
if (!emptyempty ($head [1]) && intval ($head [1]) < +) return true;
}
return false;
}

The instance code for excluding redirects is as follows:

The code is as follows:

<?php
/**
* Fetches all the real headers sent by the server in response to a HTTP request without redirects
* Get headers that do not contain redirects
*/

function Get_real_headers ($url, $format =0, $follow _redirect=0) {
if (! $follow _redirect) {
Set new default options
$opts = Array (' http ' = =
Array (' max_redirects ' =>1, ' ignore_errors ' =>1)
);
Stream_context_get_default ($opts);
}
Get headers
$headers =get_headers ($url, $format);
Restore default Options
if (Isset ($opts)) {
$opts = Array (' http ' = =
Array (' max_redirects ' =>20, ' ignore_errors ' =>0)
);
Stream_context_get_default ($opts);
}
Return
return $headers;
}
?>

I hope this article is helpful to everyone's PHP programming.

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