退出登录或注销关键代码

/**
     * 注销用户
     */
    @Override
    public String logout(HttpServletRequest request, HttpServletResponse response) {
        //获得用户认证信息
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        if(authentication != null) {
            //注销
            new SecurityContextLogoutHandler().logout(request, response, authentication);
        }
        return "redirect:/login?logout";
    }