Java Servlet过滤器混乱，响应重定向不为'；不可能

我有一个身份验证过滤器，用于阻止用户浏览您需要登录的任何页面：

public class AuthenticationFilter implements Filter {

    private FilterConfig fc;
    private final String indexURL = "/index.xhtml";
    private final String registerUrl = "/register/register.xhtml";

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.fc = filterConfig;
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        HttpSession session = req.getSession();
        UserBean user = (UserBean) session.getAttribute("userBean");
        String requestUrl = req.getRequestURI();
        System.out.println("user is " + user);
        if (user != null) {
            System.out.println("username is " + user.getUsername());
            if (user.getUsername() == null || user.getUsername().equalsIgnoreCase("")) {
                System.out.println("request url is " + requestUrl);
                if (!requestUrl.equalsIgnoreCase(indexURL) && 
                        !requestUrl.equalsIgnoreCase(registerUrl) && !requestUrl.startsWith("/javax.faces.resource")) {
                    //Redirect back to indexpage
                    System.out.println("request url is not for index/register/resource, it is: " + requestUrl);
                    resp.sendRedirect(indexURL);
                };
            }
        } else {
            resp.sendRedirect(indexURL);
        }
        chain.doFilter(req, resp);
    }

    @Override
    public void destroy() {

    }

}

它实际上正在打印我期望的内容，但它没有执行重定向，这是我的日志信息（最后一部分）：

Info:   request url is /javax.faces.resource/jquery/jquery.js.xhtml
Info:   user is be.kdg.repaircafe.beans.UserBean@350af1bb
Info:   username is null
Info:   request url is /javax.faces.resource/repaircafe_logo.png.xhtml
Info:   user is be.kdg.repaircafe.beans.UserBean@350af1bb
Info:   username is null
Info:   request url is /welcome.xhtml
Info:   request url is not for index/register/resource, it is: /welcome.xhtml
Severe:   Error Rendering View[/welcome.xhtml] --> I just told you to redirect! Why are you doing this to me??

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编辑：经过一些调试后，我发现调试器点击了链。doFilter（）即使在他重定向响应后，为什么他仍然将我转发给欢迎而不是索引？

我通过查看另一个stackoverflow答案来修复此问题，如果我在重定向后点击return，它将阻止过滤器进行转发

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是调试指针正在分别命中sendRedirect（indexURL）的代码？如果

requestUrl

和

indexURL

是相同的，我不认为它会进入if。如果重定向，则不应调用chain.doFilter（req，resp）；紧接着。当页面是受欢迎的时，过滤器似乎在循环中被击中。xhtml。是的，调试指针击中了重定向。如果您阅读了注释，您会很快发现：如果您重定向，您不应该调用chain.doFilter（req，resp）；就在我读了评论之后，但你没有提供我为什么不能这么做的依据。这似乎更多的是一种预感，而不是事实。