怎样使用php 获取远程网址头部信息

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有二种方法,

1.用php的函数get_headers
get_headers --  Fetches all the headers sent by the server in response to a HTTP request
Description
array get_headers ( string url [, int format] )
get_headers() returns an array with the headers sent by the server in response to a HTTP request. Returns FALSE on failure and an error of level E_WARNING will be issued.

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If the optional format parameter is set to 1, get_headers() parses the response and sets the array's keys.

例子 1. get_headers() example

<?php
$url = 'http://www.example.com';
print_r(get_headers($url));

print_r(get_headers($url, 1));
?> 
上例的输出类似于：

Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Date: Sat, 29 May 2004 12:28:13 GMT
    [2] => Server: Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
    [4] => ETag: "3f80f-1b6-3e1cb03b"
    [5] => Accept-Ranges: bytes
    [6] => Content-Length: 438
    [7] => Connection: close
    [8] => Content-Type: text/html
)

Array
(
    [0] => HTTP/1.1 200 OK
    [Date] => Sat, 29 May 2004 12:28:14 GMT
    [Server] => Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT
    [ETag] => "3f80f-1b6-3e1cb03b"
    [Accept-Ranges] => bytes
    [Content-Length] => 438
    [Connection] => close
    [Content-Type] => text/html
)

get_headers 是用来取得远程服务器的响应头信息的.用返回的第一个数组再加上正则就可以判断远程地址是否为200正常网页

2,用curl CURLOPT_NOBODY参数只抓取header头信息

curl函数真是个好东西,curl参数里有一项可以配置只抓取远程网页的header头信息 

如下代码,加红的地方是关健,他指定了curl抓的内容中包含header头,并且不要body内容.

function get_header($url){
 $ch  = curl_init();
 curl_setopt($ch, CURLOPT_URL, $url);
 curl_setopt($ch, CURLOPT_HEADER, true);
 curl_setopt($ch, CURLOPT_NOBODY,true);
 curl_setopt($ch, CURLOPT_RETURNTRANSFER,true);
 curl_setopt($ch, CURLOPT_FOLLOWLOCATION,true);
 curl_setopt($ch, CURLOPT_AUTOREFERER,true);
 curl_setopt($ch, CURLOPT_TIMEOUT,30);
 curl_setopt($ch, CURLOPT_HTTPHEADER, array(
 'Accept: */*',
 'User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)',
 'Connection: Keep-Alive'));
 $header = curl_exec($ch);
 return $header;
}