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($url, 1));
?>
Array
(
[0] => HTTP/1.1 200 OK
[1] => Date: Sat, 29 May 2004 12:28:13 GMT
[2] => Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)
[3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
[4] => ETag: "3f80f-1b6-3e1cb03b"
[5] => Accept-Ranges: bytes
[6] => Content-Length: 438
[7] => Connection: close
[8] => Content-Type: text/html
) Array
(
[0] => HTTP/1.1 200 OK
[Date] => Sat, 29 May 2004 12:28:14 GMT
[Server] => Apache/1.3.27 (Unix) (Red-Hat/Linux)
[Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT
[ETag] => "3f80f-1b6-3e1cb03b"
[Accept-Ranges] => bytes
[Content-Length] => 438
[Connection] => close
[Content-Type] => text/html
)
http://php.net/manual/en/function.get-headers.php
Fetches all HTTP headers from the current request.
This function is an alias for apache_request_headers(). Please read the apache_request_headers() documentation for more information on how this function works.
An associative array of all the HTTP headers in the current request, or FALSE on failure.
我们可以自己写这个函数：
在PHP里，想要得到所有的HTTP请求头，可以使用getallheaders方法，不过此方法并不是在任何环境下都存在，比如说，你使用fastcgi方式运行PHP的话，就没有这个方法，所以说我们还需要考虑别的方法，幸运的是$_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://*.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] =>
)