springmvc微信二次开发获取agent参数报错

代码中写的是
String agent = ((ShiroHttpServletRequest) request).getHeader("user-agent");
引用的也是
import org.apache.shiro.web.servlet.ShiroHttpServletRequest;
但是微信端访问的时候报错：
java.lang.ClassCastException: org.sitemesh.webapp.contentfilter.HttpServletRequestFilterable cannot be cast to org.apache.shiro.web.servlet.ShiroHttpServletRequest

类型你转换错了，你再看看文档