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
See Also:
getSession()--------------------------------------------------------------------------------getSession
public HttpSession getSession()
Returns the current session associated with this request, or if the request does not have a session, creates one.
Returns:
the HttpSession associated with this request
See Also:
getSession(boolean)
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
See Also:
getSession()--------------------------------------------------------------------------------getSession
public HttpSession getSession()
Returns the current session associated with this request, or if the request does not have a session, creates one.
Returns:
the HttpSession associated with this request
See Also:
getSession(boolean)
在无session,即从该request对象中得不到session时,建立一个新的session
而request.getSession(false)
如果得不到,那么不建立一个新的session,只返回给你一个null