Spring LDAP

Here is a simple example on how you would retrieve a user's ldap credentials using spring ldap:
http://blog.javachap.com/index.php/ldap-user-management-with-spring-ldap/

Configure a spring ldap context source:

<bean id="contextSource" class="org.springframework.security.ldap.DefaultSpringSecurityContextSource">
       <constructor-arg value="${ldap.url}"/>
       <property name="base" value="${ldap.base}"/>
       <property name="userDn" value="${ldap.username}"/>
       <property name="password" value="${ldap.password}"/>
   </bean>

   <bean id="ldapTemplate" class="org.springframework.ldap.core.LdapTemplate">
       <constructor-arg ref="contextSource"/>
   </bean>

You can then use the ldap template to query the ldap directory and map the relevant fields:

public User getUser(String userId) {
       AndFilter filter = new AndFilter();
       filter.and(new EqualsFilter("objectclass", "person")).and(
               new EqualsFilter("uid", userId));
       List<User> users = ldapTemplate.search(DistinguishedName.EMPTY_PATH,
               filter.encode(), new AttributesMapper() {
                   public Object mapFromAttributes(Attributes attributes) throws NamingException {

                       User user = new User();
                       user.setEmail(attributes.get("mail").toString());

                       return user;
                   }
               });

       if (users.isEmpty()) {
           return null;
       }
       return users.get(0);
   }