DispatcherServlet 匹配请求路径时的疑惑

存在Servlet A，其url-pattern为 /A/*，则形如/A,/A/bcd,/A/b/c/d等式样的请求全部能够被Servlet A匹配上。
但是SpringMVC的DispatcherServlet的url-pattern /A/*只能匹配上/A式样的请求，/A/abc，/A/b/c等式样的均匹配不上。
debug发现，org.springframework.web.util.UrlPathHelper.getPathWithinServletMapping()方法会将请求路径中与url-pattern配置一致的路径（servletPath）截去，然后用剩下的部分去匹配，不知这么做的用意是什么，还请各位不吝赐教

/**
     * Return the path within the servlet mapping for the given request,
     * i.e. the part of the request's URL beyond the part that called the servlet,
     * or "" if the whole URL has been used to identify the servlet.
     * <p>Detects include request URL if called within a RequestDispatcher include.
     * <p>E.g.: servlet mapping = "/*"; request URI = "/test/a" -> "/test/a".
     * <p>E.g.: servlet mapping = "/"; request URI = "/test/a" -> "/test/a".
     * <p>E.g.: servlet mapping = "/test/*"; request URI = "/test/a" -> "/a".
     * <p>E.g.: servlet mapping = "/test"; request URI = "/test" -> "".
     * <p>E.g.: servlet mapping = "/*.test"; request URI = "/a.test" -> "".
     * @param request current HTTP request
     * @return the path within the servlet mapping, or ""
     */
    public String getPathWithinServletMapping(HttpServletRequest request) {
        String pathWithinApp = getPathWithinApplication(request);
        String servletPath = getServletPath(request);
        String sanitizedPathWithinApp = getSanitizedPath(pathWithinApp);
        String path;
        // 不能理解此处的用意何在
        // If the app container sanitized the servletPath, check against the sanitized version
        if (servletPath.contains(sanitizedPathWithinApp)) {
            path = getRemainingPath(sanitizedPathWithinApp, servletPath, false);
        }
        else {
            path = getRemainingPath(pathWithinApp, servletPath, false);
        }

        if (path != null) {
            // Normal case: URI contains servlet path.
            return path;
        }
        else {
            // Special case: URI is different from servlet path.
            String pathInfo = request.getPathInfo();
            if (pathInfo != null) {
                // Use path info if available. Indicates index page within a servlet mapping?
                // e.g. with index page: URI="/", servletPath="/index.html"
                return pathInfo;
            }
            if (!this.urlDecode) {
                // No path info... (not mapped by prefix, nor by extension, nor "/*")
                // For the default servlet mapping (i.e. "/"), urlDecode=false can
                // cause issues since getServletPath() returns a decoded path.
                // If decoding pathWithinApp yields a match just use pathWithinApp.
                path = getRemainingPath(decodeInternal(request, pathWithinApp), servletPath, false);
                if (path != null) {
                    return pathWithinApp;
                }
            }
            // Otherwise, use the full servlet path.
            return servletPath;
        }
    }