Today, I wanted to set up a Tomcat engine that runs on some 80xx port so that it looks like a usual web server running on port 80. I had to fiddle with the settings for some time and maybe, you have got the same steps to do, so this is what I did:

Insert this virtual host declaration in /etc/apache2/vhosts.d/myown_vhost.conf:

<VirtualHost *:80>
    # don't lose time with IP address lookups
    HostnameLookups Off 
    # needed for named virtual hosts
    UseCanonicalName Off
    ProxyPass / http://localhost:80xx/
    ProxyPassReverse / http://localhost:80xx/

But this was not enough. Some application inside Tomcat calls request.getServerName() and still gets localhost. So, inside Tomcat, I had to edit conf/server.xml and modify the connector declaration:

<Connector port="8088"  address="localhost"  proxyName=""  proxyPort="80" ... other arguments here ...

After that, everything worked just fine.

For detailed information, see