servlet过滤器 过滤黑名单Ip 404错误找不到页面

Question

 public class MainAction implements Filter {

    /**
     * 
     */
     private String charset;
        //黑名单
        private Set<String> set = new HashSet<String>();

        @Override
        public void init(FilterConfig filterConfig) throws ServletException {

            charset = filterConfig.getInitParameter("charset");

            //到数据库中把黑名单加载进来，这里简单模拟一下
            set.add("192.168.31.168");
        }

        @Override
        public void doFilter(ServletRequest request, ServletResponse response,
                FilterChain chain) throws IOException, ServletException {
              request.setCharacterEncoding(charset);
            //以下演示黑名单过滤技术
            String ip = request.getRemoteAddr();;//获得客户端的IP
            if(set.contains(ip)){
                HttpServletResponse resp = (HttpServletResponse) response;
                resp.setContentType("text/html;charset=utf-8");
                resp.getWriter().println("你已被列入黑名单!");
            }else{//放行
                chain.doFilter(request, response);
            }
        }

        @Override
        public void destroy() {
        }


}

 <filter>
    <filter-name>MainAction</filter-name>
    <filter-class>nuc.bl.Servlet.MainAction</filter-class>
    <init-param>
        <param-name>charset</param-name>
        <param-value>utf-8</param-value>    
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>MainAction</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

Answer 1

我试了一下，，题主的方法没错，，就是本地访问本地时，不会用IP地址（测出来的，找了半天不知道什么原因。）

解决方法
【1】set.add("192.168.31.168");改成 set.add("127.0.0.1");

【2】request.getRemoteAddr();;//获得客户端的IP，，获取到的id题主可以打印一下，，是“0:0:0:0:0:0:0:1”

需要用下面方法获取，，，
String ip = getRemoteAddress((HttpServletRequest) request);

 /**
     * 获取访问IP
     * @param request
     * @return
     */
    public String getRemoteAddress(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip.equals("0:0:0:0:0:0:0:1") ? "127.0.0.1" : ip;
    }

有什么问题还可以追问，，，，，有帮助请采纳