$header_info=get_headers('//www.jb51.net/');
echo $header_info[0];
//耗时 0.67~0.78

$ch = curl_init ( '//www.jb51.net/' );
curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, 1 );
curl_exec ( $ch );
$httpcode = curl_getinfo ( $ch, CURLINFO_HTTP_CODE ); // 200
curl_close ( $ch );
echo $httpcode;
//耗时 0.84~0.94

$curl = curl_init();
$url='//www.jb51.net/';
curl_setopt($curl, CURLOPT_URL, $url); //设置URL
curl_setopt($curl, CURLOPT_HEADER, 1); //获取Header
curl_setopt($curl,CURLOPT_NOBODY,true); //Body就不要了吧，我们只是需要Head
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); //数据存到成字符串吧，别给我直接输出到屏幕了
curl_exec($curl); //开始执行啦～
$httpcode=curl_getinfo($curl,CURLINFO_HTTP_CODE); //我知道HTTPSTAT码哦～
curl_close($curl); //用完记得关掉他
echo $httpcode;
//耗时 0.45~0.53

/**
 * 获取远程URL的HTTP状态
 * 
 * @version 0.0.1
 * @Author Chenjl * 
 * @param string $url  远程URL
 * @param string $data  ture[返回HTTP状态数组] | false[返回状态数值]
 * 
 * @return mixed
 */
function getHeaders($url,$data=FALSE){
 $_headers = get_headers($url,1);
 if( !$data ){return $_headers;}
 $curl = curl_init(); 
 curl_setopt($curl,CURLOPT_URL,$url);//获取内容url 
 curl_setopt($curl,CURLOPT_HEADER,1);//获取http头信息 
 curl_setopt($curl,CURLOPT_NOBODY,1);//不返回html的body信息 
 curl_setopt($curl,CURLOPT_RETURNTRANSFER,1);//返回数据流，不直接输出 
 curl_setopt($curl,CURLOPT_TIMEOUT,30); //超时时长，单位秒 
 curl_exec($curl); 
 $rtn= curl_getinfo($curl,CURLINFO_HTTP_CODE); 
 curl_close($curl);
 return $rtn;
}

# 调用案例1：getHeaders('//www.jb51.net\/\',true);
# 返回结果：200 // 直接返回HTTP状态码
 
# 调用案例2：getHeaders('//www.jb51.net/',false);
# 返回结果：
/*
array(10) { 
[0]=> 
string(15) "HTTP/1.1 200 OK" 
["Server"]=> 
string(5) "nginx" 
["Date"]=> 
string(29) "Mon, 04 Jul 2016 06:21:35 GMT" 
["Content-Type"]=> 
string(9) "text/html" 
["Content-Length"]=> 
string(5) "26898" 
["Last-Modified"]=> 
string(29) "Mon, 04 Jul 2016 06:16:00 GMT" 
["Connection"]=> 
string(5) "close" 
["Vary"]=> 
string(15) "Accept-Encoding" 
["ETag"]=> 
string(15) ""5779ff20-6912"" 
["Accept-Ranges"]=> 
string(5) "bytes" 
} 
*/