购物车_拦截器

拦截器：

public class CartInterceptor implements HandlerInterceptor {
    public static ThreadLocal<UserInfoTo> toThreadLocal = new ThreadLocal<>();
    /***
     * 目标方法执行之前
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        UserInfoTo userInfoTo = new UserInfoTo();
        HttpSession session = request.getSession();
        //获得当前登录用户的信息
        MemberResponseVo memberResponseVo = (MemberResponseVo) session.getAttribute(LOGIN_USER);

        if (memberResponseVo != null) {
            //用户登录了
            userInfoTo.setUserId(memberResponseVo.getId());
        }

        Cookie[] cookies = request.getCookies();
        if (cookies != null && cookies.length > 0) {
            for (Cookie cookie : cookies) {
                //user-key
                String name = cookie.getName();
                if (name.equals(TEMP_USER_COOKIE_NAME)) {
                    userInfoTo.setUserKey(cookie.getValue());
                    //标记为已是临时用户
                    userInfoTo.setTempUser(true);
                }
            }
        }

        //如果没有临时用户一定分配一个临时用户
        if (StringUtils.isEmpty(userInfoTo.getUserKey())) {
            String uuid = UUID.randomUUID().toString();
            userInfoTo.setUserKey(uuid);
        }

        //目标方法执行之前
        toThreadLocal.set(userInfoTo);
        return true;
    }


    /**
     * 业务执行之后，分配临时用户来浏览器保存
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

        //获取当前用户的值
        UserInfoTo userInfoTo = toThreadLocal.get();

        //如果没有临时用户一定保存一个临时用户
        if (!userInfoTo.getTempUser()) {
            //创建一个cookie
            Cookie cookie = new Cookie(TEMP_USER_COOKIE_NAME, userInfoTo.getUserKey());
            //扩大作用域
            cookie.setDomain("gulimall.com");
            //设置过期时间
            cookie.setMaxAge(TEMP_USER_COOKIE_TIMEOUT);
            response.addCookie(cookie);
        }

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

指定拦截请求：

@Configuration
public class GulimallWebConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new CartInterceptor())//注册拦截器
                .addPathPatterns("/**");
    }
}