HI, ALL,
At first , thank you very much for helping me about the session problem.
but now i have a problem as follow:

i  run a  servlet of opening the excel or word file in the remote 
browse.
when i open the servlet in the client browse,  the pc  can pop_up  a 
dialog box.
and ask  you to key in the  atestation information , including the 
username and password.  but i don't set up  any username and password in 
the work/excel file and servlet file.
 and if i press the Cancel button , i can open the word/excel file in 
the client browse.
i wonder why  and i don't want the dialog box, please help me .
thanks in advance!
Best Regards!