php用Curl的post方法只获取header头信息中的Location

$posturl="http://www.ie81.com/posturl";   
$postdata="a=1&b=2";           
$ch = curl_init();   
curl_setopt($ch, CURLOPT_POST, 1);   
curl_setopt($ch, CURLOPT_URL,$posturl);   
curl_setopt($ch, CURLOPT_REFERER,"");//REFERER   
curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);   
curl_setopt($ch, CURLOPT_HEADER, 1);    
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);     
$content = curl_exec($ch);    
curl_close($ch);   
// 解析HTTP数据流    
list($header, $body) = explode("\r\n\r\n", $content);     
preg_match("/Location:([^\r\n]*)/i", $header, $matches);    
$Location = $matches[1];   
if($Location!=""){   
    echo $Location
}   
else{ echo "未获取到";}