A.直接返回會(huì)話對(duì)象
B.當(dāng)服務(wù)器已經(jīng)創(chuàng)建了會(huì)話對(duì)象就返回該對(duì)象,否則返回null
C.直接返回null
D.當(dāng)服務(wù)器已經(jīng)創(chuàng)建了會(huì)話對(duì)象就返回該對(duì)象,否則新建一個(gè)會(huì)話對(duì)象并返回
A.ServletConfig
B.HttpServlet
C.Cookie
D.HttpServletRequest