There are lots of ways to accomplish this. You could setup another tomcat instance that contains the site-down page, and simply switch the IP on your firewall to point to this new server instead of the maintenance server.
This will work for planned maint.. for unplanned maint or unexpected tomcat crashes/issues a common practice is to use an http server (such as apache) infront of your app server, then use Mod_JK to connect them.
Hope that helps.
Joined: May 08, 2009
1) First I dont't want to go for another tomcat instance.
2) I try something in .htaccess file but nothing is working like this
The apache instance that is integrated with tomcat doesn't have the same feature set as a standard apache install. So, I wouldn't be suprised if rewrites don't work. The rewrite mod doesn't even come with a full Apache install off the shelf. You have to install the rewrite_mod.
Also, I don't believe this will solve your problem. If Tomcat is taken down, so will the apache server that's integrated with it.