Filter

Filter: 过滤器用来过滤网站的数据

实现javax.servelt.Filter这个接口定义的三个方法：init，doFilter和destory

1. 编写过滤器

   导包要选servlet

   package com.yu.filter;
   
   import javax.servlet.*;
   import java.io.IOException;
   
   public class CharacterEncodingFilter implements Filter {
       public void init(FilterConfig filterConfig) throws ServletException {
   
       }
   
       public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
   
       }
   
       public void destroy() {
   
       }
   }

2. web.xml

   <filter>
       <filter-name>CharacterEncodingFilter</filter-name>
       <filter-class>com.yu.filter.CharacterEncodingFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>CharacterEncodingFilter</filter-name>
       <!-- 只要是/servlet的任何请求都要经过这个过滤器-->
       <url-pattern>/servlet/*</url-pattern>
   </filter-mapping>

Filter过滤器

原文：https://www.cnblogs.com/w00dyblog/p/12528804.html