This is the simplest way to do it. Allows for group authorities, as well as user authorities.
-- Postgres syntax
create table users (
user_id serial primary key,
enabled boolean not null default true,
password text not null,
username citext not null unique
);
create index on users (username);
create table groups (
group_id serial primary key,
name citext not null unique
);
create table authorities (
authority_id serial primary key,
authority citext not null unique
);
create table user_authorities (
user_id int references users,
authority_id int references authorities,
primary key (user_id, authority_id)
);
create table group_users (
group_id int references groups,
user_id int referenecs users,
primary key (group_id, user_id)
);
create table group_authorities (
group_id int references groups,
authority_id int references authorities,
primary key (group_id, authority_id)
);
Then in META-INF/applicationContext-security.xml
<beans:bean class="org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder" id="passwordEncoder" />
<authentication-manager>
<authentication-provider>
<jdbc-user-service
data-source-ref="dataSource"
users-by-username-query="select username, password, enabled from users where username=?"
authorities-by-username-query="select users.username, authorities.authority from users join user_authorities using(user_id) join authorities using(authority_id) where users.username=?"
group-authorities-by-username-query="select groups.id, groups.name, authorities.authority from users join group_users using(user_id) join groups using(group_id) join group_authorities using(group_id) join authorities using(authority_id) where users.username=?"
/>
<password-encoder ref="passwordEncoder" />
</authentication-provider>
</authentication-manager>