delphi使用ajax添加一个cookie

uses Comobj;

var
  url:string;
  xmlHttp:Olevariant;
  responseText:Widestring;
begin
  url:='http://xxx.cn/xx.asp';
  try
    xmlHttp:=CreateOleObject('Msxml2.XMLHTTP');
    xmlHttp.open('POST',url,false);
    xmlHttp.setRequestHeader('Cookie', 'cookietest=testvalue');
    xmlHttp.send('xxxx');
    responseText:=xmlHttp.responseText;
    if xmlHttp.status='200' then
    begin
      //--
    end
    else
    begin
      //--
    end;
  except
    On E:Exception do
      //--
  end;
end;