如何从弹簧安全中获取当前登录的用户对象？

我使用的是Spring安全版本3.1.4.RELEASE。如何访问当前登录的用户对象？

SecurityContextHolder.getContext().getAuthentication().getPrinciple()

返回用户名，而不是用户对象。那么我如何使用返回的用户名并获取UserDetails对象呢？

我尝试了以下代码：

public UserDetails getLoggedInUser(){

    final Authentication auth = SecurityContextHolder.getContext().getAuthentication();
    if (auth != null && auth.isAuthenticated() && !(auth instanceof AnonymousAuthenticationToken))
    {
        if(auth.getDetails() !=null)
            System.out.println(auth.getDetails().getClass());
        if( auth.getDetails() instanceof UserDetails)
        {
            System.out.println("UserDetails");
        }
        else
        {
            System.out.println("!UserDetails");
        }
    }
    return null;
}

结果如下：

[2015-08-17 19:44:46.738] INFO  http-bio-8443-exec-423   System.out    class org.springframework.security.web.authentication.WebAuthenticationDetails 
[2015-08-17 19:44:46.738] INFO  http-bio-8443-exec-423   System.out    !UserDetails

身份验证筛选器类，如下所示：

public class CustomUsernamePasswordAuthenticationFilter extends AbstractAuthenticationProcessingFilter {
    public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "j_username";
    public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "j_password";
    public static final String SPRING_SECURITY_LAST_USERNAME_KEY = "SPRING_SECURITY_LAST_USERNAME";
    private String usernameParameter = SPRING_SECURITY_FORM_USERNAME_KEY;
    private String passwordParameter = SPRING_SECURITY_FORM_PASSWORD_KEY;
    private boolean postOnly = true;

    public CustomUsernamePasswordAuthenticationFilter() {
        super("/j_spring_security_check");
    }

    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException {
        if (postOnly && !request.getMethod().equals("POST")) {
            throw new AuthenticationServiceException("Authentication method not supported: " + request.getMethod());
        }

        String username = obtainUsername(request);
        String password = obtainPassword(request);
        if (username == null) {
            username = "";
        }
        if (password == null) {
            password = "";
        }
        username = username.trim();
        UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(username, password);

        // Allow subclasses to set the "details" property
        setDetails(request, authRequest);
        if(this.getAuthenticationManager()==null){
            logger.info("Authentication manager is null.");
        } else {
            logger.info("Authentication manager was "+this.getAuthenticationManager().getClass().getName()); 
        }
        return this.getAuthenticationManager().authenticate(authRequest);
    }

    protected String obtainPassword(HttpServletRequest request) {
        return request.getParameter(passwordParameter);
    }

    protected String obtainUsername(HttpServletRequest request) {
        return request.getParameter(usernameParameter);
    }

    protected void setDetails(HttpServletRequest request, UsernamePasswordAuthenticationToken authRequest) {
        authRequest.setDetails(authenticationDetailsSource.buildDetails(request));
    }

    public void setUsernameParameter(String usernameParameter) {
        this.usernameParameter = usernameParameter;
    }

    public void setPasswordParameter(String passwordParameter) {
        this.passwordParameter = passwordParameter;
    }

    public void setPostOnly(boolean postOnly) {
        this.postOnly = postOnly;
    }

    public final String getUsernameParameter() {
        return usernameParameter;
    }

    public final String getPasswordParameter() {
        return passwordParameter;
    }
}

身份验证提供程序，如下所示：

@Component
public class CustomAuthenticationProvider extends AbstractUserDetailsAuthenticationProvider {
    private MyUserDetailsService userDetailsService;

    public MyUserDetailsService getUserDetailsService() {
        return userDetailsService;
    }

    public void setUserDetailsService(MyUserDetailsService userDetailsService) {
        this.userDetailsService = userDetailsService;
    }

    @Override
    protected void additionalAuthenticationChecks(UserDetails arg0,
            UsernamePasswordAuthenticationToken arg1)
            throws AuthenticationException {

    }

    @Override
    protected UserDetails retrieveUser(String arg0,
            UsernamePasswordAuthenticationToken arg1)
            throws AuthenticationException {
        return userDetailsService.loadUserByUsername(arg0);
    }
}

用户详细信息类如下所示：

    public class MyUserDetailsService implements UserDetailsService {       
    private final Map<String, UserDetails> usersList;

    public MyUserDetailsService() {
        Collection<GrantedAuthority> authorityList;
        final SimpleGrantedAuthority supervisorAuthority = new SimpleGrantedAuthority("supervisor");
        final SimpleGrantedAuthority userAuthority = new SimpleGrantedAuthority("user");
        usersList = new TreeMap<String, UserDetails>();

        authorityList = new ArrayList<GrantedAuthority>();
        authorityList.add(supervisorAuthority);
        authorityList.add(userAuthority);
        usersList.put("admin", new User("admin", "admin", authorityList));

        authorityList = new ArrayList<GrantedAuthority>();
        authorityList.add(userAuthority);
        usersList.put("peter", new User("peter", "password123", authorityList));

        //probably don't use this in production
        for(Map.Entry<String, UserDetails> user : usersList.entrySet()){
            logger.info(user.getValue().toString());
        }
    }

    @Override
    public UserDetails loadUserByUsername(String username)throws UsernameNotFoundException {
        UserDetails ud = usersList.get(username);
        if (ud != null) {
            logger.info("loadUserByUsername: found match, returning "
                    + ud.getUsername() + ":" + ud.getPassword() + ":"
                    + ud.getAuthorities().toString());
            return new User(ud.getUsername(), ud.getPassword(),
                    ud.getAuthorities());
        }

        logger.info("loadUserByUsername: did not find match, throwing UsernameNotFoundException");
        throw new UsernameNotFoundException(username);
    }
}