Filter设计实现IP地址限制

 1 package com.mhb;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.Filter;
 7 import javax.servlet.FilterChain;
 8 import javax.servlet.FilterConfig;
 9 import javax.servlet.ServletException;
10 import javax.servlet.ServletRequest;
11 import javax.servlet.ServletResponse;
12 
13 public class IPFilter implements Filter {
14 
15 protected FilterConfig filterConfig;
16 protected String ip;
17 
18 public void init(FilterConfig filterConfig) throws ServletException {
19 this.filterConfig = filterConfig;    //设置属性filterConfig
20 this.ip = this.filterConfig.getInitParameter("ip");    //设置初始化参数IP
21 }
22 //过滤方法
23 public void doFilter(ServletRequest request, ServletResponse response,
24 FilterChain chain) throws IOException, ServletException {
25 String remoteIP = request.getLocalAddr();    //获得客户端ip地址
26 
27 if(remoteIP.equals(ip)){    //判断IP是否被禁止
28 response.setCharacterEncoding("gb2312");    //设置输出内容编码格式
29 PrintWriter out = response.getWriter();
30 out.println("<b>你的IP地址被禁止访问！</b>");
31 }else{
32 chain.doFilter(request, response);
33 }
34 }
35 //销毁方法
36 public void destroy() {
37 }
38 }

 <filter>
      <filter-name>IPFilter</filter-name>
      <filter-class>com.mhb.IPFilter</filter-class>
      <init-param>
       <param-name>ip</param-name>
       <param-value>127.0.0.1</param-value>
      </init-param>
  </filter>
  <filter-mapping>
       <filter-name>IPFilter</filter-name>
       <url-pattern>/*</url-pattern>
  </filter-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>