httpsession.getattribute

`HttpSession.getAttribute()` 是一个方法，用于从当前会话中获取指定名称的属性值。具体来说，当在客户端与服务器之间建立一个会话时，服务器会分配一个唯一的会话 ID，并将其存储在客户端浏览器的 Cookie 中。在此会话期间，应用程序可以使用 `HttpSession` 对象存储和检索数据。通过调用 `getAttribute()` 方法，应用程序可以从会话中获取已存储的数据。

相关问题

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { if (handler instanceof HandlerMethod) { HandlerMethod handlerMethod = (HandlerMethod) handler; Method method = handlerMethod.getMethod(); RepeatSubmit annotation = method.getAnnotation(RepeatSubmit.class); if (annotation != null) { if (this.isRepeatSubmit(request, annotation)) { AjaxResult ajaxResult = AjaxResult.error(annotation.message()); ServletUtils.renderString(response, JSON.toJSONString(ajaxResult)); return false; } } } boolean flag = false; TokenService tokenService = SpringUtils.getBean(TokenService.class); LoginAppUser loginUser = tokenService.getLoginUser(request); if (loginUser != null && loginUser.getGuest() != null && loginUser.getGuest().getGuestNum() != null) { tokenService.verifyToken(loginUser); String guestNum = loginUser.getGuest().getGuestNum(); HttpSession httpSession = request.getSession(); RedisCache redisUtil = SpringUtils.getBean(RedisCache.class); Guest guest = redisUtil.getCacheMapValue(RedisConstants.GUEST_MAP, guestNum); SysGuest sysGuest = JSON.parseObject(JSON.toJSONString(guest), SysGuest.class); if (sysGuest == null) { flag = false; httpSession.removeAttribute(Constants.SERVER_TYPE_APP); } else { if (httpSession.getAttribute(Constants.SERVER_TYPE_APP) == null) { httpSession.setAttribute(Constants.SERVER_TYPE_APP , sysGuest); } return true; } } 优化这段代码

首先，可以将该方法拆分成两个方法，一个处理重复提交的逻辑，一个处理登录用户的逻辑，以提高代码可读性和可维护性。

处理重复提交的逻辑可以改为使用注解方式，遍历所有的参数，判断是否存在 @Token 注解，如果存在则验证 token 是否一致。

处理登录用户的逻辑可以简化代码，将获取当前登录用户和验证 token 的逻辑移动到 TokenService 中，简化该方法代码。

重构后的代码如下所示：

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    if (handler instanceof HandlerMethod) {
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        Method method = handlerMethod.getMethod();
        Token annotation = method.getAnnotation(Token.class);
        if (annotation != null) {
            if (!tokenService.verifyToken(request)) {
                AjaxResult ajaxResult = AjaxResult.error(annotation.message());
                ServletUtils.renderString(response, JSON.toJSONString(ajaxResult));
                return false;
            }
        }
    }

    if (tokenService.checkLogin(request)) {
        HttpSession session = request.getSession();
        if (session.getAttribute(Constants.SERVER_TYPE_APP) == null) {
            session.setAttribute(Constants.SERVER_TYPE_APP, tokenService.getLoginUser(request).getGuest());
        }
        return true;
    } else {
        ServletUtils.renderString(response, JSON.toJSONString(AjaxResult.error(HttpStatus.UNAUTHORIZED.value(), "未登录或登录超时。")));
        return false;
    }
}

其中，`TokenService` 的实现中包括了 `verifyToken` 和 `checkLogin` 方法，分别用于验证 token 和检查当前用户是否已经登录。同时，重复提交的逻辑使用 `@Token` 注解进行处理。

重构这个方法将其认知复杂度从17降低到允许的15：public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { if (handler instanceof HandlerMethod) { HandlerMethod handlerMethod = (HandlerMethod) handler; Method method = handlerMethod.getMethod(); RepeatSubmit annotation = method.getAnnotation(RepeatSubmit.class); if (annotation != null) { if (this.isRepeatSubmit(request, annotation)) { AjaxResult ajaxResult = AjaxResult.error(annotation.message()); ServletUtils.renderString(response, JSON.toJSONString(ajaxResult)); return false; } } } boolean flag = false; TokenService tokenService = SpringUtils.getBean(TokenService.class); LoginAppUser loginUser = tokenService.getLoginUser(request); if (loginUser != null && loginUser.getGuest() != null && loginUser.getGuest().getGuestNum() != null) { tokenService.verifyToken(loginUser); String guestNum = loginUser.getGuest().getGuestNum(); HttpSession httpSession = request.getSession(); RedisCache redisUtil = SpringUtils.getBean(RedisCache.class); Guest guest = redisUtil.getCacheMapValue(RedisConstants.GUEST_MAP, guestNum); SysGuest sysGuest = JSON.parseObject(JSON.toJSONString(guest), SysGuest.class); if (sysGuest == null) { flag = false; httpSession.removeAttribute(Constants.SERVER_TYPE_APP); } else { if (httpSession.getAttribute(Constants.SERVER_TYPE_APP) == null) { httpSession.setAttribute(Constants.SERVER_TYPE_APP , sysGuest); } return true; } } //获取网名 也就是/login String servletPath = request.getServletPath(); if(servletPath.contains("/app/card/isCard") || servletPath.contains("/app/bank/signingBankCard") || servletPath.contains("/app/bank/sendMessage") || servletPath.contains("/app/bank/sendSysMessage") || servletPath.contains("/app/bank/login") || servletPath.contains("/app/card/guestIdAndPhone") || servletPath.contains("/app/family/isDevice") || servletPath.contains("/websocket/") || servletPath.contains("/upload/") || servletPath.contains("/app/deviceSocket/toSocket")) { flag = true; } if (!flag) { noLogin(response); } return flag; }

首先，可以将整个方法拆分成几个小的方法，这样可以使代码更易于维护和测试。其次，可以将注解的判断提取出来，避免在方法中嵌套过多的if语句。最后，可以将获取网名的代码块与其他代码块分开，这样可以使代码更加清晰易懂。

以下是重构后的代码示例：

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    if (isRepeatSubmit(request, handler)) {
        renderRepeatSubmitError(response);
        return false;
    }

    boolean flag = false;
    LoginAppUser loginUser = getLoginUser(request);
    if (loginUser != null) {
        flag = setServerTypeApp(request, loginUser);
    }

    if (!flag) {
        flag = checkIfNoLogin(request);
    }

    return flag;
}

private boolean isRepeatSubmit(HttpServletRequest request, Object handler) {
    if (!(handler instanceof HandlerMethod)) {
        return false;
    }

    HandlerMethod handlerMethod = (HandlerMethod) handler;
    Method method = handlerMethod.getMethod();
    RepeatSubmit annotation = method.getAnnotation(RepeatSubmit.class);
    return annotation != null && this.isRepeatSubmit(request, annotation);
}

private boolean setServerTypeApp(HttpServletRequest request, LoginAppUser loginUser) {
    boolean flag = false;
    if (loginUser.getGuest() != null && loginUser.getGuest().getGuestNum() != null) {
        TokenService tokenService = SpringUtils.getBean(TokenService.class);
        tokenService.verifyToken(loginUser);
        String guestNum = loginUser.getGuest().getGuestNum();
        RedisCache redisUtil = SpringUtils.getBean(RedisCache.class);
        Guest guest = redisUtil.getCacheMapValue(RedisConstants.GUEST_MAP, guestNum);
        SysGuest sysGuest = JSON.parseObject(JSON.toJSONString(guest), SysGuest.class);
        if (sysGuest != null) {
            HttpSession httpSession = request.getSession();
            if (httpSession.getAttribute(Constants.SERVER_TYPE_APP) == null) {
                httpSession.setAttribute(Constants.SERVER_TYPE_APP, sysGuest);
            }
            flag = true;
        } else {
            HttpSession httpSession = request.getSession();
            httpSession.removeAttribute(Constants.SERVER_TYPE_APP);
        }
    }
    return flag;
}

private boolean checkIfNoLogin(HttpServletRequest request) {
    String servletPath = request.getServletPath();
    return servletPath.contains("/app/card/isCard")
            || servletPath.contains("/app/bank/signingBankCard")
            || servletPath.contains("/app/bank/sendMessage")
            || servletPath.contains("/app/bank/sendSysMessage")
            || servletPath.contains("/app/bank/login")
            || servletPath.contains("/app/card/guestIdAndPhone")
            || servletPath.contains("/app/family/isDevice")
            || servletPath.contains("/websocket/")
            || servletPath.contains("/upload/")
            || servletPath.contains("/app/deviceSocket/toSocket");
}

private void renderRepeatSubmitError(HttpServletResponse response) throws IOException {
    AjaxResult ajaxResult = AjaxResult.error(annotation.message());
    ServletUtils.renderString(response, JSON.toJSONString(ajaxResult));
}

private void noLogin(HttpServletResponse response) throws IOException {
    AjaxResult ajaxResult = AjaxResult.error("未登录或登录超时。请重新登录。");
    ServletUtils.renderString(response, JSON.toJSONString(ajaxResult));
}

private LoginAppUser getLoginUser(HttpServletRequest request) {
    TokenService tokenService = SpringUtils.getBean(TokenService.class);
    return tokenService.getLoginUser(request);
}

这样将认知复杂度降低到了15以下，同时使代码更加易于维护和测试。