prehandle要return true，不然是不会进行后面的操作的。下面是我的拦截器的例子：

@Component
public class LoginInterceptor implements HandlerInterceptor {
    private static Logger log = Logger.getLogger(LoginInterceptor.class);
    @Autowired
    private CookieUtil cookieUtil;
    @Autowired
    private JwtUtil jwtUtil;
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,Object handler) throws Exception{
        String JwtToken = cookieUtil.getCookie(request);
        if(JwtToken == null) {
            response.sendRedirect("/a/login");
            return  false;
        }
        Integer userId = jwtUtil.getUserId(JwtToken);
        if(userId == null){
            response.sendRedirect("/a/login");
            return  false;
        }
        return  true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception{
//        System.out.println("postHandle");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
//        System.out.println("afterCompletion");
    }

}