A FilterChain is an object provided by the servlet container to the developer
giving a view into the invocation chain of a filtered request for a resource. Filters
use the FilterChain to invoke the next filter in the chain, or if the calling filter
is the last filter in the chain, to invoke the rosource at the end of the chain.
doFilter(ServletRequest request,
ServletResponse response)
Causes the next filter in the chain to be invoked, or if the calling filter is the last filter
in the chain, causes the resource at the end of the chain to be invoked.
Causes the next filter in the chain to be invoked, or if the calling filter is the last filter
in the chain, causes the resource at the end of the chain to be invoked.