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一：用注解配置：@WebFilter("/*")
package wo.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;//过滤器入门@WebFilter("/*")public class FilterDemo1 implements Filter{ @Override public void destroy() { // TODO Auto-generated method stub } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { System.out.println("filterdemo1执行了"); //放行 chain.doFilter(request, response); } @Override public void init(FilterConfig filterConfig) throws ServletException { // TODO Auto-generated method stub }} 二：web.xml配置
demo1 wo.filter.FilterDemo1 demo1 /*
三：生命周期
1. init:在服务器启动后，会创建Filter对象，然后调用init方法。只执行一次。用于加载资源 2. doFilter:每一次请求被拦截资源时，会执行。执行多次 3. destroy:在服务器关闭后，Filter对象被销毁。如果服务器是正常关闭，则会执行destroy方法。只执行一次。用于释放资源package wo.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;/** * Servlet Filter implementation class FilterDemo2 */@WebFilter("/*")public class FilterDemo3 implements Filter { /** * Default constructor. */ public FilterDemo3() { // TODO Auto-generated constructor stub } /** * @see Filter#destroy() */ public void destroy() { //释放资源 System.out.println("destroy......"); } /** * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain) */ public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { System.out.println("doFilter....."); chain.doFilter(request, response); } /** * @see Filter#init(FilterConfig) */ public void init(FilterConfig fConfig) throws ServletException { System.out.println("init......");//加载资源 }} 转载地址：http://tdezi.baihongyu.com/