php 原生或curl获取 http headers

有一个函数：

array get_headers ( string $url [, int $format = 0 ] )

Parameters

url
　　The target URL.

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

　　设置为非0返会解析响应关联数组。
Return Values

　　Returns an indexed or associative array with the headers, or FALSE on failure.

<?php
$url = 'http://www.example.com';

print_r(get_headers($url));

print_r(get_headers($url, 1));
?>

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
)

http://php.net/manual/en/function.get-headers.php

array getallheaders ( void )

Fetches all HTTP headers from the current request.

This function is an alias for apache_request_headers(). Please read the apache_request_headers() documentation for more information on how this function works.

An associative array of all the HTTP headers in the current request, or FALSE on failure.

我们可以自己写这个函数：

　　在PHP里，想要得到所有的HTTP请求头，可以使用getallheaders方法，不过此方法并不是在任何环境下都存在，比如说，你使用fastcgi方式运行PHP的话，就没有这个方法，所以说我们还需要考虑别的方法，幸运的是$_SERVER里有我们想要的东西，它里面键名以HTTP_开头的就是HTTP请求头：

$headers = array(); 
foreach ($_SERVER as $key => $value) { 
    if ('HTTP_' == substr($key, 0, 5)) { 
        $headers[str_replace('_', '-', substr($key, 5))] = $value; 
    } 
}

代码很简单，需要说明的是RFC里明确指出了信息头的名字是不区分大小写的。

不过并不是所有的HTTP请求头都是以HTTP_开头的的键的形式存在与$_SERVER里，比如说Authorization，Content-Length，Content-Type就不是这样，所以说为了取得所有的HTTP请求头，还需要加上下面这段代码：

if (isset($_SERVER['PHP_AUTH_DIGEST'])) { 
    $header['AUTHORIZATION'] = $_SERVER['PHP_AUTH_DIGEST']); 
} elseif (isset($_SERVER['PHP_AUTH_USER']) && isset($_SERVER['PHP_AUTH_PW'])) { 
    $header['AUTHORIZATION'] = base64_encode($_SERVER['PHP_AUTH_USER'] . ':' . $_SERVER['PHP_AUTH_PW'])); 
} 
if (isset($_SERVER['CONTENT_LENGTH'])) { 
    $header['CONTENT-LENGTH'] = $_SERVER['CONTENT_LENGTH']; 
} 
if (isset($_SERVER['CONTENT_TYPE'])) { 
    $header['CONTENT-TYPE'] = $_SERVER['CONTENT_TYPE']; //注意-和下划线不同
}

http://php.net/manual/zh/function.getallheaders.php

我用$_SERVER['CONTENT_TYPE']出现

Undefined index: CONTENT_TYPE。

curl设置header：http://blog.51yip.com/php/1297.html

curl获取content type

<?php
  # the request
  $ch = curl_init('http://www.google.com');
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  curl_exec($ch);

  # get the content type
  echo curl_getinfo($ch, CURLINFO_CONTENT_TYPE);

  # output
  text/html; charset=ISO-8859-1
?>

参考：http://stackoverflow.com/questions/2610713/get-mime-type-of-external-file-using-curl-and-php

我们curl_getinfo如果后面只有一个参数，返回一个array：

$httpinfo=curl_getinfo($ch);
print_r( $httpinfo);

返回如：

Array
(
    [url] => http://www.php10086.com/2012/04/605.html
    [content_type] => text/html; charset=UTF-8
    [http_code] => 200
    [header_size] => 344
    [request_size] => 71
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 1.545
    [namelookup_time] => 0
    [connect_time] => 0.172
    [pretransfer_time] => 0.172
    [size_upload] => 0
    [size_download] => 54618
    [speed_download] => 35351
    [speed_upload] => 0
    [download_content_length] => -1
    [upload_content_length] => 0
    [starttransfer_time] => 0.593
    [redirect_time] => 0
    [certinfo] => Array
        (
        )

    [primary_ip] => 173.254.29.116
    [primary_port] => 80
    [local_ip] => 192.168.1.5
    [local_port] => 49970
    [redirect_url] => 
)