SpringMVC如何使用拦截器控制登录

<c:if test="${sessionScope.login == null || sessionScope.login == false}">
 <!-- 未登录 -->
 <c:redirect url="/login"/>
</c:if>
<c:if test="${sessionScope.login}">
 <!-- 已登录 -->
</c:if>

<!-- <mvc:mapping path="/**" /> 如果只写一个*，则不能拦截类似/*/*的请求。静态资源的请求需要判断不进行拦截 -->
<mvc:interceptors>
 <mvc:interceptor>
  <mvc:mapping path="/**" />
  <bean class="com.ts.settle.tools.interceptor.LoginInterceptor">
   <property name="excludedUrls">
    <list>
     <value>/login</value>
     <value>/static/</value>
    </list>
   </property>
  </bean>
 </mvc:interceptor>
</mvc:interceptors>

public class LoginInterceptor implements HandlerInterceptor {
 private AvatarLogger logger = AvatarLoggerFactory.getLogger(this.getClass());

 private List<String> excludedUrls;

 /**
  * 在DispatcherServlet完全处理完请求后被调用
  * 当拦截器抛出异常时,依然会从当前拦截器往回执行所的拦截器的afterCompletion()
  */
 public void afterCompletion(HttpServletRequest request,
        HttpServletResponse response, Object handler, Exception exception)
   throws Exception {

 }

 //在业务处理器处理请求执行完成后,生成视图之前执行的动作
 public void postHandle(HttpServletRequest request, HttpServletResponse response,
       Object handler, ModelAndView modelAndView) throws Exception {

 }

 /**
  * 在业务处理器处理请求之前被调用
  * 如果返回false 则退出本拦截器，本拦截器后面的postHandle与afterCompletion不再执行
  */
 public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
        Object handler) throws Exception {

  String requestUri = request.getRequestURI();
  for (String url : excludedUrls) {
   if (requestUri.contains(url)) {
    return true;
   }
  }

  HttpSession session = request.getSession();
  Boolean login = (Boolean) session.getAttribute("login");
  if (login == null || !login) {
   //System.out.println(request.getContextPath());
   logger.info("Pedirect to login page");
   response.sendRedirect(request.getContextPath() + "/login");
  }
  return true;
 }

 public void setExcludedUrls(List<String> excludedUrls) {
  this.excludedUrls = excludedUrls;
 }
}