If you want to do authorization yourself,
JNDI makes it possible to bounce credentials off an LDAP server.
JAAS may be another option, though I've never used it.
I prefer to rely on the container for authentication and authorization. You will have to look at your server's documentation for how to configure it to talk to the LDAP server.
Here is the relevant documentation for
Tomcat. You then use your web.xml to declare what security roles have access to your application.
See here for more on that.