<!-- 安全认证过滤器 -->
 <bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
  <property name="securityManager" ref="securityManager" />
  <property name="loginUrl" value="/b/login" />
  <property name="successUrl" value="/b" />
  <property name="filters">
   <map>
    <!--退出过滤器-->
    <entry key="logout" value-ref="systemLogoutFilter" />
   </map>
  </property>
  <property name="filterChainDefinitions">
   <value>
    /b/login = authc
    /b/logout = logout
    /b/** = user
   </value>
  </property>
 </bean>

@Service
public class SystemLogoutFilter extends LogoutFilter {
 @Override
 protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
  //在这里执行退出系统前需要清空的数据


　　　　　Subject subject = getSubject(request, response);

  String redirectUrl = getRedirectUrl(request, response, subject);

  try {

   subject.logout();

  } catch (SessionException ise) {

   ise.printStackTrace();

  }

  issueRedirect(request, response, redirectUrl);

　　　　　//返回false表示不执行后续的过滤器，直接返回跳转到登录页面

  return false;
 }
}

<entry key="logout" value-ref="systemLogoutFilter" />