UserService.java

package com.sheetsj.account;

import java.util.Collections;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;

import com.sheetsj.util.BusinessValidationException;

public class UserService implements UserDetailsService {
	
	@Autowired
	private AccountRepository accountRepository;
	
	@Value("${another.property}")
	private String anotherProperty;
	
	@PostConstruct	
	protected void initialize() {
		if (accountRepository.findByEmail("user") == null) {
			accountRepository.save(new Account("user", "demo", "ROLE_USER"));
			accountRepository.save(new Account("admin", "admin", "ROLE_ADMIN"));
		}
	}
	
	@Override
	public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
		if (username == null || username.length() < 3) {
			throw new BusinessValidationException("username", "username.too.short", username);
		}
		
		Account account = accountRepository.findByEmail(username);
		if(account == null) {
			throw new UsernameNotFoundException("user not found");
		}
		return createUser(account);
	}
	
	public void signin(Account account) {
		SecurityContextHolder.getContext().setAuthentication(authenticate(account));
	}
	
	private Authentication authenticate(Account account) {
		return new UsernamePasswordAuthenticationToken(createUser(account), null, Collections.singleton(createAuthority(account)));		
	}
	
	private User createUser(Account account) {
		return new User(account.getEmail(), account.getPassword(), Collections.singleton(createAuthority(account)));
	}

	private GrantedAuthority createAuthority(Account account) {
		return new SimpleGrantedAuthority(account.getRole());
	}

	protected String getAnotherProperty() {
		return anotherProperty;
	}

}