vim /usr/local/apache2/conf/extra/httpd-vhosts.conf

<IfModule mod_expires.c>

    ExpiresActive on
    ExpiresByType p_w_picpath/gif  "access plus 1 days"
    ExpiresByType p_w_picpath/jpeg "access plus 24 hours"
    ExpiresByType p_w_picpath/png "access plus 24 hours"
    ExpiresByType text/css "now plus 2 hour"
    ExpiresByType application/x-javascript "now plus 2 hours"   
    ExpiresByType application/javascript "now plus 2 hours"
    ExpiresByType application/x-shockwave-flash "now plus 2 hours"
    ExpiresDefault "now plus 0 min"
</IfModule>