Several ways to determine whether a remote file exists in PHP

When I was making a picture preview, I encountered a problem, which was to determine whether the remote file existed (not on the same server).

The code is as follows:

0102030405060708091011121314151617181920212223242526272829303132333435 //Method one function

file_exists($url){$ch

= curl_init();curl_setopt($ch,

curlopt_url,$url);curl_setopt($ch,

curlopt_nobody, 1); //

Do not download curl_setopt($ch,

curlopt_failonerror, 1);curl_setopt($ch,

curlopt_returntransfer, 1); if(curl_exec($ch)!==false)return

true;elsereturn

false;} //Method 2 function

file_exists2($url){if(file_get_contents($url,0,null,0,1))return

1;elsereturn

0;}//Method three function

file_exists($url)

{$curl

= curl_init($url);//

Do not retrieve data curl_setopt($curl,

CURLOPT_NOBODY, true);//

Send request $result

= curl_exec($curl);$found

= false;//

If the request is not sent and fails if

($result

!== false) {//

Check again whether the http response code is 200}

Method 1 returns FALSE regardless of whether the image is present;

Method 2 is feasible under Windows. Under LINUX, TRUE will be returned regardless of whether the picture is present;

Method 3 should be the most suitable

In addition: There are efficiency issues with the get_headers() method, and it is recommended not to use it as this solution

fsockopen version:

01020304050607080910111213141516171819 $url

= "http://www.baidu.com/img/baidu_sylogo1.gif"; $info

= parse_url($url); $fp

= fsockopen($info['host'],

80,$errno,

$errstr,

30); fputs($fp,"GET

{$info['path']} HTTP/1.1rn"); fputs($fp,

"Host:

{$info['host']}rn"); fputs($fp,

"Connection:

closernrn"); $headers

= array(); while(!feof($fp))

{ $line

= fgets($fp); if($line

!= "rn")

{ $headers[]

= $line; }else

{ break; } } echo

"; print_r($headers);

Use the http status code to determine whether the file exists. For example, responses 302, 301, 404, etc. all mean that the file does not exist. If it is 200, 304, etc., it can be regarded as the file exists.

fopen() method:

010203040506070809101112

= 'http://www.test.com/images/test.jpg'; if(

@fopen(

$url,

'r'

) ) { echo

'File Exits'; } else else { echo

'File Do Not Exits'; } ?>

CURL method:

01020304050607080910111213141516

= 'http://www.test.com/test.jpg'; $ch

= curl_init(); $timeout

= 10; curl_setopt

($ch,

CURLOPT_URL, $url2); curl_setopt($ch,

CURLOPT_HEADER, 1); curl_setopt

($ch,

CURLOPT_RETURNTRANSFER, 1); curl_setopt

($ch,

CURLOPT_CONNECTTIMEOUT, $timeout); $contents

= curl_exec($ch); //echo

$contents; if

(preg_match("/404/",

$contents)){ echo

'File does not exist'; }

Related labels：

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