本文实例讲述了PHP使用get_headers函数判断远程文件是否存在的方法。分享给大家供大家参考。具体实现方法如下：
以前讲过程关于php判断远程文件是否存在的文章都是利用fopen,sockt,curl函数来实现检查远程文件是否存在,下面我再介绍利用 get_headers来检查远程文件是否存在,感兴趣的朋友可以参考一下。
先来简单了解get_headers()函数
get_headers() 返回一个数组m包含有服务器响应一个 HTTP 请求所发送的标头。
get_headers：发送服务器响应HTTP请求
get_headers(字符串url[链接格式])
get_headers()以数组的形式返回服务器HTTP请求m如果执行失败,将返回FALSE和一个错误的水平E_WARNING,
可选参数设置为1,get_headers()能分析系统的响应速度和集数组中的键,
注意:使用该函数需要把 php.ini里面的allow_url_fopen = On,才能使用
实例代码如下:
复制代码 代码如下:
<?php
$url = 'http://www.zzvips.com';
print_r(get_headers($url));
print_r(get_headers($url, 1));
?>
$url = 'http://www.zzvips.com';
print_r(get_headers($url));
print_r(get_headers($url, 1));
?>
运行结果如下：
复制代码 代码如下:
Array
(
[0] => HTTP/1.1 200 OK
[1] => Cache-Control: max-age=1800
[2] => Content-Length: 54874
[3] => Content-Type: text/html
[4] => Content-Location: http://www.zzvips.com/
[5] => Last-Modified: Fri, 28 Nov 2014 03:34:56 GMT
[6] => Accept-Ranges: bytes
[7] => ETag: "b66ba847bcad01:bc5"
[8] => Server: Microsoft-IIS/6.0
[9] => Date: Fri, 28 Nov 2014 03:37:34 GMT
[10] => Connection: close
)
Array
(
[0] => HTTP/1.1 200 OK
[Cache-Control] => max-age=1800
[Content-Length] => 54874
[Content-Type] => text/html
[Content-Location] => http://www.zzvips.com/
[Last-Modified] => Fri, 28 Nov 2014 03:34:56 GMT
[Accept-Ranges] => bytes
[ETag] => "b66ba847bcad01:bc5"
[Server] => Microsoft-IIS/6.0
[Date] => Fri, 28 Nov 2014 03:37:35 GMT
[Connection] => close
)
(
[0] => HTTP/1.1 200 OK
[1] => Cache-Control: max-age=1800
[2] => Content-Length: 54874
[3] => Content-Type: text/html
[4] => Content-Location: http://www.zzvips.com/
[5] => Last-Modified: Fri, 28 Nov 2014 03:34:56 GMT
[6] => Accept-Ranges: bytes
[7] => ETag: "b66ba847bcad01:bc5"
[8] => Server: Microsoft-IIS/6.0
[9] => Date: Fri, 28 Nov 2014 03:37:34 GMT
[10] => Connection: close
)
Array
(
[0] => HTTP/1.1 200 OK
[Cache-Control] => max-age=1800
[Content-Length] => 54874
[Content-Type] => text/html
[Content-Location] => http://www.zzvips.com/
[Last-Modified] => Fri, 28 Nov 2014 03:34:56 GMT
[Accept-Ranges] => bytes
[ETag] => "b66ba847bcad01:bc5"
[Server] => Microsoft-IIS/6.0
[Date] => Fri, 28 Nov 2014 03:37:35 GMT
[Connection] => close
)
判断远程文件是否存在代码如下:
复制代码 代码如下:
//判断远程文件是否存在
function remote_file_exists($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($head[1]) < 400) return true;
}
return false;
}
function remote_file_exists($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($head[1]) < 400) return true;
}
return false;
}
排除重定向的实例代码如下:
复制代码 代码如下:
<?php
/**
* Fetches all the real headers sent by the server in response to a HTTP request without redirects
* 获取不包含重定向的报头
*/
function get_real_headers($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 $headers;
}
?>
/**
* Fetches all the real headers sent by the server in response to a HTTP request without redirects
* 获取不包含重定向的报头
*/
function get_real_headers($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;
}
?>
希望本文所述对大家的PHP程序设计有所帮助。
