java 从 ServletRequest 获取 Cookie
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Get Cookies from ServletRequest
提问by Ben
I'm using ServletRequestListenerto attach to new requests, get a ServletRequestobject and extract cookies from it.
我正在使用ServletRequestListener附加到新请求，获取一个ServletRequest对象并从中提取 cookie。
I've noticed that only HTTPServletRequesthas cookies but I haven't found a connection between those two objects.
我注意到只有HTTPServletRequestcookie，但我还没有找到这两个对象之间的联系。
Is it okay to use
可以用吗
HttpServletRequest request = ((HttpServletRequest) FacesContext.getCurrentInstance()
.getExternalContext().getRequest());
to retrieve the request while in a RequestInitializedmethod? (I do want to run on every request)
在RequestInitialized方法中检索请求？（我确实想在每个请求上运行）
FYI - This is all done in a JSF 1.2 Application
仅供参考 - 这一切都在 JSF 1.2 应用程序中完成
回答by BalusC
This is not correct. The FacesContextisn't available in a ServletRequestListenerper se. The getCurrentInstance()might return null, leading to NPE's.
这是不正确的。该FacesContext不是一个可用的ServletRequestListener本身。将getCurrentInstance()可能会返回null，导致NPE的。
If you're running the webapp on a HTTP webserver (and thus not some Portlet webserver for example), you could just cast the ServletRequestto HttpServletRequest.
如果你正在运行在HTTP Web服务器（因此不是一些Portlet的Web服务器为例）的Web应用程序，你可以只投的ServletRequest到HttpServletRequest。
public void requestInitialized(ServletRequestEvent event) {
HttpServletRequest request = (HttpServletRequest) event.getServletRequest();
// ...
}
Note that a more common practice is to use a Filterfor this since you can map this on a fixed URL pattern like *.jsfor even on specific servlets so that it runs only when the FacesServletruns. You might for example want to skip cookie checks on static resources like CSS/JS/images.
请注意，更常见的做法是为此使用 a Filter，因为您可以将其映射到固定的 URL 模式，例如*.jsf甚至特定的 servlet，以便它仅在FacesServlet运行时运行。例如，您可能希望跳过对 CSS/JS/图像等静态资源的 cookie 检查。
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
HttpServletRequest request = (HttpServletRequest) req;
// ...
chain.doFilter(req, res);
}
When you happens to be already inside the JSF context (in a managed bean, phaselistener or whatever), you could just use ExternalContext#getRequestCookieMap()to get the cookies.
当您碰巧已经在 JSF 上下文中（在托管 bean、阶段侦听器或其他任何东西中）时，您可以使用ExternalContext#getRequestCookieMap()来获取 cookie。
Map<String, Object> cookies = externalContext.getRequestCookieMap();
// ...
When running JSF on top of Servlet API, the map value is of type javax.servlet.http.Cookie.
在 Servlet API 之上运行 JSF 时，映射值的类型为javax.servlet.http.Cookie。
Cookie cookie = (Cookie) cookies.get("name");
回答by nfechner
Yes, you can do that. In Web scenarios, this will always be ok. If you want to be sure, you could do a check for the type first. (Good practice anyway):
是的，你可以这样做。在 Web 场景中，这总是没问题的。如果你想确定，你可以先检查一下类型。（无论如何都是好习惯）：
if (FacesContext.getCurrentInstance().getExternalContext().getRequest() instanceof HttpServletRequest) {
...
By the way: Why do you have to use FacesContext? From where are you calling this code?
顺便说一句：你为什么要使用FacesContext？你从哪里调用这个代码？
