转发来自过滤器的请求 [英] Forward request from a filter

问题描述

如果原始请求的URI通过一些验证，我需要从http.Filter
转发请求（到一个jsp，但我认为这不重要）过滤器运行。

我发现这个面临类似任务的页面

我仍然需要计算以下内容：如何获得 doFilter（）方法中的ServletContext（为了call forward API） getServletContext（）不被重新分配

我是否需要在转发之前调用chain.doFilter（），转发之前还是根本没有？
另外，如果我的验证通过了，或者只有失败了，我才需要调用 chain.doFilter（）（因为在这种情况下我不会继续前进我的网页）？

这个问题实际上是继续 this thread ，
更明显，代码可能类似于：

preublic $ doFilter（ServletRequest request，ServletResponse response，FilterChain chain）throws IOException，ServletException {$ b $ if（request instanceof HttpServletRequest）{
HttpServletRequest httpServletRequest =（（HttpServletRequest）请求）;
String requestURI = httpServletRequest.getRequestURI（）;
String contextPath = httpServletRequest.getContextPath（）;
if（<这是我实现这个过滤器的验证>）{
getServletContext（）。getRequestDispatcher（
MySpecific.jsp）。forward（request，response）;



$ b chain.doFilter（request，response）;

$ b $ / code $ / pre

解决方案

如何在doFilter（）方法中获得ServletContext？

  httpServletRequest。 。的getSession（）的getServletContext（）; 
  

我必须在转发之前调用chain.doFilter（）在转发之前还是根本不？另外，如果我的验证通过了，或者只有失败了（因为在这种情况下我不会继续转发我的页面），我还需要调用chain.doFilter（）吗？

我会说，如果你转发请求，你不应该调用 chain.doFilter（） - 转发的请求将被过滤到它自己的过滤器配置。如果你的验证失败，这取决于你的Web应用程序的语义是什么 - 如果原始页面是某种一般的错误/登录/欢迎屏幕，你可能想要继续，当验证失败。如果不了解更多情况，很难说。

I need to forward my request (to a jsp but I don't think it's matter) from an http.Filter if the URI of the original request pass some validation that my filter runs.

I found this page that faced similar task

Still I need to figure the following:

1. How can I get ServletContext in doFilter() method (in order to call forward API) getServletContext() is not recignized

2. Do I have to call chain.doFilter() before the forward, after the forward or not at all? In addition do I have to call chain.doFilter() if my validation passed or only if it fails (because in this case I won't continue to forward my page)?

This question actually continue this thread, to be more obvious, the code could be something like:

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        if (request instanceof HttpServletRequest) {
            HttpServletRequest httpServletRequest = ((HttpServletRequest)request);
            String requestURI = httpServletRequest.getRequestURI();
            String contextPath = httpServletRequest.getContextPath();
            if (<this is my implementation of the validation of this filter>){                                      
                getServletContext().getRequestDispatcher(
                "MySpecific.jsp").forward(request,response);

            }

        }
        chain.doFilter(request,response);

    }

解决方案

How can I get ServletContext in doFilter() method?

httpServletRequest.getSession().getServletContext();

Do I have to call chain.doFilter() before the forward, after the forward or not at all? In addition do I have to call chain.doFilter() if my validation passed or only if it fails (because in this case I won't continue to forward my page)?

I would say that if you forwarded the request, you should not call chain.doFilter() - the forwarded request will get filtered according to its own filter configuration. If your validation failed though, it depends on what the semantics of your web app are - if the original page is some sort of general error/login/welcome screen, you may want to continue to that when the validation failed. It is hard to say without knowing more of the context.

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