lwp已经添加了cookie_jar 为什么服务器还是返回 Set-Cookie

yakczh_cu

1. 
   
2. use 5.01;
   
3. use HTTP::Request;
   
4. use LWP::UserAgent;
   
5. use HTTP::Cookies;
   
6. use Data::Dumper;
   
7. 
   
8. my $url='http://bbs.chinaunix.net';
   
9. my $cookie_jar = HTTP::Cookies->new(    file => 'cookie.dat' ,    autosave => 1,ignore_discard=>1);
   
10. 
    
11. my $ua = LWP::UserAgent->new(agent=> 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.6) Gecko/20091201 Firefox/3.5.6');
    
12.   $ua->cookie_jar($cookie_jar);
    
13. my $req = HTTP::Request->new(GET => $url);
    
14. my $res = $ua->request($req);
    
15. say  $req->as_string;
    
16. 
    
17. # HTML back
    
18. if ($res->is_success)
    
19. {
    
20. say $res->headers->as_string;
    
21. }
    

复制代码

如果浏览器请求已经添加了 Cookie头 ,服务器不应该再返回  Set-Cookie 但是运行结果还是返回  
et-Cookie: ndfU_81a3_sid=6RB2I3; expires=Tue, 29-Mar-2016 06:02:30 GMT; Max-Age=86400; path=/; domain=.chinaunix.net
Set-Cookie: ndfU_81a3_lastact=145914950%09forum.php%09; expires=Tue, 29-Mar-2016 06:02:30 GMT; Max-Age=86400; path=/; domain=.chinaunix.net
Set-Cookie: ndfU_81a3_cloudstatpost=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; domain=.chinaunix.net
Set-Cookie: ndfU_81a3_sid=6RB2I3; expires=Tue, 29-Mar-2016 06:02:30 GMT; Max-Age=86400; path=/; domain=.chinaunix.net

tmp

"服务器不应该再返回  Set-Cookie" 为什么不应该?