拦截器 实现 spring家的handlerInterceptor
可以看下就是拦截前 中 后

public interface HandlerInterceptor {
    default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
    }

    default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
    }
}

拦截器类+threadLocal

threadlocal中的类型为 实现serilaizeble的序列化的Vo

@Component
public class MyInterceptor implements HandlerInterceptor {

    private static ThreadLocal<MemberRespVo> threadLocal = new ThreadLocal();

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (request.getSession().getAttribute("loginUser") == null) {
            response.sendRedirect("http://www.baidu.com");
            return false;
        } else {
            threadLocal.set((MemberRespVo) request.getSession().getAttribute("loginUser"));
            System.out.println("获得了"+threadLocal.get());
            return true;
        }
    }
}

拦截器配置类 在容器中加入拦截器 让它对应的url中生效

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private  MyInterceptor myInterceptor;


    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor).addPathPatterns("/**");
    }
}