1. load module

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

2. virtual host

<VirtualHost *:80>
    ServerName jsp.jirak.net
    CustomLog logs/jsp.jirak.net-access.log common
    ErrorLog logs/jsp.jirak.net-error.log
    ProxyRequests Off
    ProxyPreserveHost On
    <Proxy *>
        Order deny,allow
        Allow from all
    </Proxy>
    ProxyPass / http://localhost:8080/
    ProxyPassReverse / http://localhost:8080/
</VirtualHost>