request.getSession() 方法
HttpRequest对象有两种形式的getSession方法调用：
一个是getSession()，
另一个是getSession(boolean isNew)
这样的，前者会检测当前是否有session存在，如果不存在则创建一个，如果存在就返回当前的。
getSession()相当于getSession(true)，
参数为true时，若存在会话则返回该会话，否则新建一个会话。
参数为false时，若存在会话则返回该会话，否则应该返回一个NULL
这是文档：
getSession?
? public?? HttpSession?? getSession(boolean?? create)Returns?? the?? current?? HttpSession?? associated?? with?? this?? request?? or,?? if?? if?? there?? is?? no?? current?? session?? and?? create?? is?? true,?? returns?? a?? new?? session.???
? If?? create?? is?? false?? and?? the?? request?? has?? no?? valid?? HttpSession,?? this?? method?? returns?? null.???
??
? To?? make?? sure?? the?? session?? is?? properly?? maintained,?? you?? must?? call?? this?? method?? before?? the?? response?? is?? committed.?? If?? the?? container?? is?? using?? cookies?? to?? maintain?? session?? integrity?? and?? is?? asked?? to?? create?? a?? new?? session?? when?? the?? response?? is?? committed,?? an?? IllegalStateException?? is?? thrown.?
??
? Parameters:?
? true?? -?? to?? create?? a?? new?? session?? for?? this?? request?? if?? necessary;?? false?? to?? return?? null?? if?? there's?? no?? current?? session?
? Returns:?
? the?? HttpSession?? associated?? with?? this?? request?? or?? null?? if?? create?? is?? false?? and?? the?? request?? has?? no?? valid?? session??
?
1 楼 jerquer 2011-09-06 getSession()相当于getSession(false)吧 2 楼 comeonbabye 2011-09-07 请参看API: