在使用SpringSecurity4時無法自動注入service層：程式碼如下：

@Service("customUserDetailsService")
@Transactional(readOnly = true)
public class CustomUserDetailsService implements UserDetailsService {

    @Autowired
    private  UserService userService;


    public UserDetails loadUserByUsername(String username) throws
 
 UsernameNotFoundException {
        System.out.println("username>>>>"+username);
        User user = userService.findByUserName(username);
        System.out.println("user>>>>"+user);
        if (user == null ){
            System.out.println("User not found");
            throw
 
 new UsernameNotFoundException("Username not found");
        }
        return new org.springframework.security.core.userdetails.User(user.getUserName(),user.getPassWord(),
                user.getState().equals("Activite"),true,
                true,true,getGrantedAuthorities(user));

    }


    private
 
 List<GrantedAuthority> getGrantedAuthorities(User user){
        List<GrantedAuthority> authorities = new ArrayList<GrantedAuthority>();
        for(UserToProfileid userToProfileid : user.getUserToProfileidHashSet()){
            System.out.println("userToProfileid : "+userToProfileid);
            authorities.add(new SimpleGrantedAuthority("ROLE_"+userToProfileid.getProfileid().getType()));
        }
        System.out.print("authorities :"+authorities);
        return authorities;
    }
}

在執行上段程式碼是userService一直是空指標異常，後來用dao嘗試也是一樣，報錯NPE,
解決辦法：
後來查閱資料發現是因為專案的載入問題，在執行專案時，spring的載入檔案還沒有載入進來，所以導致無法，對於這種處理方式只需要在啟動專案是載入下spring的配置檔案：
只要對web.xml新增以下內容即可：

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
      classpath:config/spring-security.xml
      classpath:config/spring-mvc.xml   //載入spring配置檔案
    </param-value>
  </context-param>