Introduction

In repository pattern, Martin told us how to use Repository to isolate domain object accessing. With generic in Java 5, we can implement a generic repository easyly.

Details

The basic repository provide methods get(identifier), save(entity), delete(entity), loadAll(), deleteAll(Collection). You can extend EntityRepository like

Create Repository with Special Interface

        public interface UserRepository extends EntityRepository<User, String> {
        }

and configure it as a spring bean

	<util:bean id="userRepository" interfaces="cn.muthos.polyforms.sample.repository.UserRepository" />

and use it like below:

        public class UserAction {
            @Autowired
            private UserRepository userRepository;
        }

Create Repository with Implementation

Sometimes you need implement addition repository methods, repository also support it. But you need provide a implmentation class for this, eg.

        public abstract class UserRepositoryImpl implements UserRepository {
            @Autowired
            private UserDao userDao;

            List<User> findByName(String name) {
                 return userDao.findByName(name);
            }
        }

	<util:bean id="userRepository" class="cn.muthos.polyforms.sample.repository.impl.UserRepositoryImpl" />

You just need implement partial repository methods, let the repository implementation be a abstract class.

Notice When you add your implementation to repository, you also can inject other bean (eg. dao, repository) as normal spring bean.