php获取请求url时响应的报头信息几种方法

    1、用file_get_contents或者fopen、file、readfile等函数读取url的时候，会创建一个名 为$http_response_header的变量来保存http响应的报头.

    示例代码一：

   HTTP/1.1 200 OK
            [1] => Date: Tue, 06 Nov 2012 08:51:01 GMT
            [2] => Server: BWS/1.0
            [3] => Content-Length: 9803
            [4] => Content-Type: text/html;charset=gbk
            [5] => Cache-Control: private
            [6] => Expires: Tue, 06 Nov 2012 08:51:01 GMT
            [7] => Set-Cookie: BAIDUID=6635735B51B28640F425F802C49340F2:FG=1; 
            expires=Tue, 06-Nov-42 08:51:01 GMT; path=/; domain=.baidu.com
            [8] => P3P: CP=" OTI DSP COR IVA OUR IND COM "
            [9] => Connection: Close
      )      
  ?>

    2、使用fopen等函数打开的数据流信息可以用 stream_get_meta_data来获取。

示例代码二：

    Array
        (
            [0] => HTTP/1.1 200 OK
            [1] => Date: Tue, 06 Nov 2012 08:54:22 GMT
            [2] => Server: BWS/1.0
            [3] => Content-Length: 9803
            [4] => Content-Type: text/html;charset=gbk
            [5] => Cache-Control: private
            [6] => Expires: Tue, 06 Nov 2012 08:54:22 GMT
            [7] => Set-Cookie: BAIDUID=347578BCBD709F27925BDD8B05364A73:FG=1;
             expires=Tue, 06-Nov-42 08:54:22 GMT; path=/; domain=.baidu.com
            [8] => P3P: CP=" OTI DSP COR IVA OUR IND COM "
            [9] => Connection: Close
        )

    [wrapper_type] => http
    [stream_type] => tcp_socket
    [mode] => r
    [unread_bytes] => 0
    [seekable] => 
    [uri] => http://www.baidu.com
    [timed_out] => 
    [blocked] => 1
    [eof] => 
)
?>

    3、get_headers()也可以获取请求url的响应报文。

示例代码三：

  HTTP/1.1 200 OK
    [1] => Date: Tue, 06 Nov 2012 08:58:41 GMT
    [2] => Server: BWS/1.0
    [3] => Content-Length: 9803
    [4] => Content-Type: text/html;charset=gbk
    [5] => Cache-Control: private
    [6] => Expires: Tue, 06 Nov 2012 08:58:41 GMT
    [7] => Set-Cookie: BAIDUID=87B6F26EEC74F2B8F7FABA934DC6BB24:FG=1; 
    expires=Tue, 06-Nov-42 08:58:41 GMT; path=/; domain=.baidu.com
    [8] => P3P: CP=" OTI DSP COR IVA OUR IND COM "
    [9] => Connection: Close
)
?>

    4、php5中新增的参数context使这些函数更加灵活，通过它我们可以定制http请 求，甚至post数据。