public class FlashMapFilter extends OncePerRequestFilter {
@Override
@SuppressWarnings("unchecked")
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
HttpSession session = request.getSession(false);
if (session != null) {
Map<String, ?> flash = (Map<String, ?>) session.getAttribute(FlashMap.FLASH_MAP_ATTRIBUTE);
if (flash != null) {
for (Map.Entry<String, ?> entry : flash.entrySet()) {
Object currentValue = request.getAttribute(entry.getKey());
if (currentValue == null) {
request.setAttribute(entry.getKey(), entry.getValue());
}
}
session.removeAttribute(FlashMap.FLASH_MAP_ATTRIBUTE);
}
}
filterChain.doFilter(request, response);
}
}
而不是每个请求显示一次Flash消息,这会显示一条消息,消息之前的两个完整请求的持续时间。这是为什么?为什么我的FlashMapFilter显示两个请求,即使它扩展了OncePerRequestFilter?