Springmvc拦截器执行顺序及各方法作用详解

@Component
public class AuthInterceptor implements HandlerInterceptor {
 private static final String TOKEN_COOKIE = "token";
 @Autowired
 private UserDao userDao;
 @Override
 public boolean preHandle(HttpServletRequest req, HttpServletResponse res, Object handler)
     throws Exception {
  Map<String, String[]> map = req.getParameterMap();
  map.forEach((k,v) ->req.setAttribute(k, Joiner.on(",").join(v)));
  String requestURI = req.getRequestURI();
  if (requestURI.startsWith("/static") || requestURI.startsWith("/error")) {
   return true;
  }
  Cookie cookie = WebUtils.getCookie(req, TOKEN_COOKIE);
  if (cookie != null && StringUtils.isNoneBlank(cookie.getValue())) {
    User user = userDao.getUserByToken(cookie.getValue());
    if (user != null) {
     req.setAttribute(CommonConstants.LOGIN_USER_ATTRIBUTE, user);
     UserContext.setUser(user);
    }
  }
  return true;
 }
 @Override
 public void postHandle(HttpServletRequest req, HttpServletResponse res, Object handler,
     ModelAndView modelAndView) throws Exception {
  String requestURI = req.getRequestURI();
  if (requestURI.startsWith("/static") || requestURI.startsWith("/error")) {
   return ;
  }
  User user = UserContext.getUser();
  if (user != null && StringUtils.isNoneBlank(user.getToken())) {
    String token = requestURI.startsWith("logout")? "" : user.getToken();
    Cookie cookie = new Cookie(TOKEN_COOKIE, token);
    cookie.setPath("/");
    cookie.setHttpOnly(false);
    res.addCookie(cookie);
  }
 }
 @Override
 public void afterCompletion(HttpServletRequest req, HttpServletResponse response, Object handler, Exception ex)
     throws Exception {
  UserContext.remove();
 }
}