shiro解决两个请求的sessionId相同，但是某一个传入sessionId之后找不到session的原因

public class ShiroUtils {

    public static String getUsername(String token, HttpServletRequest request, HttpServletResponse response) {
        String username = null;
        String sessionID = token;
        if (sessionID == null) {
            return "null";
        } else {
            SessionKey key = new WebSessionKey(sessionID, request, response);
            try {
                Session se = SecurityUtils.getSecurityManager().getSession(key);
//                解决因为session过期而导致的异常直接抛出到前端
                if (se == null) {
                    return "null";
                }
                Object obj = se.getAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
                SimplePrincipalCollection coll = (SimplePrincipalCollection) obj;
                username = coll.getPrimaryPrincipal().toString();
            } catch (Exception e) {
//                e.printStackTrace();
                return "null";
            } finally {
            }
            return username;
        }
    }

}