java - Spring MVC 的 Cookie 问题

Question

我试图使用 @Cookie 获取 cookie 值。但是如果 cookie 值为空，我会收到 400 错误。怎么了？这是我的 Controller :

    public String listContacts(Map<String, Object> map,
            HttpServletResponse response, @CookieValue("flag") String flag) {



        response.addCookie(new Cookie("flag", "In use"));
...

Answer 1

尝试在 @CookieValue 注释中设置 required = false:

public String listContacts(Map<String, Object> map,
      HttpServletResponse response, @CookieValue(value = "flag", required = false) String flag) {

默认情况下，spring 期望 cookie header 存在，否则抛出异常:

Default is true, leading to an exception being thrown in case the header is missing in the request. Switch this to false if you prefer a null in case of the missing header.

Alternatively, provide a defaultValue, which implicitly sets this flag to false.