package com.learn;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * Created by Administrator on 2017/09/29.
 */
public class NoteFilter implements Filter {

 private FilterConfig config = null;

 private String ipTable = null; //ip名单


 @Override
 public void init(FilterConfig filterConfig) throws ServletException {
  System.out.println("note filter initial");
  this.config = filterConfig;
  this.ipTable = config.getInitParameter("ipTable");

 }

 @Override
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
  System.out.println("do filter starting");

  //校验ip地址
  if(!veryfyIP(request,response))
   return;

  long befor = System.currentTimeMillis();
  config.getServletContext().log("before call note Filter");

  chain.doFilter(request,response);

  config.getServletContext().log("after call note Filter");
  long after = System.currentTimeMillis();

  String name ="";
  if(request instanceof HttpServletRequest){
   name = ((HttpServletRequest) request).getRequestURI();
  }
  config.getServletContext().log("Note Filter : name:"+name +" time :"+(after -befor)+"ms");


 }

 @Override
 public void destroy() {

 }

 private boolean veryfyIP(ServletRequest request, ServletResponse response){

  String ip = request.getRemoteAddr();
  System.out.println("请求ip:"+ip);
  System.out.println("ipTable 黑名单:"+ipTable);

  if(ip.indexOf(ipTable) == -1){
   System.out.println("校验不通过");
   response.setContentType("text/html");
   PrintWriter out = null;
   try {
    out = response.getWriter();
    out.print("<h1>对不起，你的ip不能访问服务器</h1>");
    out.flush();
    out.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   return false;

  } else {
   return true;
  }

 }


}

package com.learn;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Created by Administrator on 2017/09/29.
 */
public class NoteServlet extends HttpServlet {

 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  System.out.println("已经通过了过滤器");


 }
}

<filter>
  <filter-name>ip</filter-name>
  <filter-class>com.learn.NoteFilter</filter-class>
  <init-param>
   <param-name>ipTable</param-name>
   <param-value>127.0.0.1</param-value>
  </init-param>
 </filter>
 <filter-mapping>
  <filter-name>ip</filter-name>
  <url-pattern>/note</url-pattern>
 </filter-mapping>

<servlet>
  <servlet-name>note</servlet-name>
  <servlet-class>com.learn.NoteServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>note</servlet-name>
  <url-pattern>/note</url-pattern>
 </servlet-mapping>