1.定义拦截器：

//定义用户拦截器
public class UserInterceptor implements HandlerInterceptor{
    
    @Autowired
    private JedisCluster jedisCluster;
    private ObjectMapper objectMapper = new ObjectMapper();
    
    /**
     * 1.获取用户Cookie获取token数据
     * 2.判断token中是否有数据
     *         false 表示没有登陆,则重定向到用户登陆页面
     *         
     *         true :表示用户之前登陆过        
     *             从redis中根据token获取userJSON,
     *             再次判断数据是否有数据
     *             
     *             false: 没有数据,则重定向到用户登陆页面
     *             true : 表示有数据,则程序予以放行.
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        //1.获取Cookiez中的token
        String token = null;
        Cookie[] cookies = request.getCookies();
        for (Cookie cookie : cookies) {
            if("JT_TICKET".equals(cookie.getName())){
                token = cookie.getValue();
                break;
            }
        }
        
        //2.判断token是否有数据
        if(token != null){
            //2.1判断redis集群中是否有数据
            String userJSON = jedisCluster.get(token);
            if(userJSON != null){
                User user = objectMapper.readValue(userJSON,User.class);
                //将user数据保存到ThreadLocal中
                UserThreadLocal.set(user);
                //证明用户已经登陆 予以放行
                return true;
            }
        }
        
        //配置重定向
        response.sendRedirect("/user/login.html");
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        
        //关闭threadLocal
        UserThreadLocal.remove();
        
    }
}

2.配置拦截器

    <!--配置拦截器  
        ((bean | ref) | interceptor)+
        
        bean 拦截器的bean标签    
        <ref/>  对象的引用
        <mvc:mapping path=""/> 拦截器拦截的路径
        <mvc:exclude-mapping path=""/> 不需要拦截的路径
        
        path="/cart/*"   只能拦截/cart/一级目录
        path="/cart/**"  拦截/cart/全部目录
        
        定义单个拦截器
        Content Model : (mapping+, exclude-mapping*, (bean | ref))
     -->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/cart/**"/>
            <mvc:mapping path="/order/**"/>
            <bean class="com.jt.web.interceptor.UserInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>