为什么我的 Http 过滤器会无限循环？

Question

我想实现一个 Http 过滤器来拦截对我的网站发出的一些请求。我想拦截对http://www.mywebsite.com/referral/userid 的请求。我编写了以下过滤器类：

public class ReferralFilter implements Filter{


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
         HttpServletRequest httpRequest = (HttpServletRequest) request;
            String contextPath = ((HttpServletRequest) request).getContextPath();
            String requestURI = httpRequest.getRequestURI();

            requestURI = StringUtils.substringAfter(requestURI, contextPath);
            if(StringUtils.contains(requestURI, "/referral/")){
                String referralIdentifier = StringUtils.substringAfter(requestURI, contextPath+"/referral/");
                //Search the referral's user
                if(referralIdentifier!=null && referralIdentifier.length()==12){

                        String cookieKey = "website.referral";
                        String cookieValue = referralIdentifier;
                        Cookie cookie = new Cookie(cookieKey,cookieValue);
                        cookie.setMaxAge(60*60*24*365);
                        ((HttpServletResponse) response).addCookie(cookie);
                        //redirect to the home page angularJS app
                        requestURI = StringUtils.substringBeforeLast(requestURI,"/referral/")+"#";



                }


            }

            String newURI = requestURI;
            request.getRequestDispatcher(newURI).forward(request, response);

    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

}

这是我的配置：

@Configuration
@AutoConfigureAfter(CacheConfiguration.class)
public class WebConfigurer implements ServletContextInitializer, EmbeddedServletContainerCustomizer {

    private final Logger log = LoggerFactory.getLogger(WebConfigurer.class);

    @Inject
    private Environment env;

    @Autowired(required = false)
    private MetricRegistry metricRegistry;

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        log.info("Web application configuration, using profiles: {}", Arrays.toString(env.getActiveProfiles()));
        EnumSet<DispatcherType> disps = EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.ASYNC);

        // some initializations

        initReferralFilter(servletContext,disps);
        log.info("Web application fully configured");
    }



    /**
     * Initializes the Referral filter.
     */
    private void initReferralFilter(ServletContext servletContext, EnumSet<DispatcherType> disps) {
        log.debug("Registering Referral Filter");
        FilterRegistration.Dynamic referralFilter = servletContext.addFilter("referralFilter", new ReferralFilter());
        referralFilter.addMappingForUrlPatterns(disps, true, "/referral/*");
           }

    // other methods
}

当我尝试访问http://www.mywebsite.com/referral/eRfdg54GDGd2 时，我的过滤器会无限执行。为什么？

谢谢

Answer 1

您的过滤器配置为在对格式为 /referral/* 的某个 URL 执行 FORWARD 时执行。当您从过滤器代码中转发到具有该表单的 URL 时，您的过滤器会一次又一次地执行，等等，所以您有一个无限递归。

尝试从此行中删除DispatcherType.FORWARD：

EnumSet<DispatcherType> disps = EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.ASYNC);

另一种方法是更改​​您的应用程序 URL，以便您转发到未被过滤器拦截的 URL。

除此之外，您永远不会让过滤器链继续下去。如果您不想中断您的请求，则必须将此行放在您的 doFilter() 方法中：

chain.doFilter(request, response);

我不知道你是否要让链条继续下去，这只是为了澄清。