Servlet规范三个技术之一 ----- Filter 过滤器 初体验

 

 

 

 

 

 

 

 

 

myFilter.java  (/booksStore/src/com/exp/filter/MyFilter.java)

package com.exp.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;

public class MyFilter implements Filter {

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("过滤器对象的初始化");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        //放行请求
        //chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

}

 

web.xml   (/booksStore/WebContent/WEB-INF/web.xml)

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>booksStore</display-name>
  
  <!-- 配置一个ServletContext监听器  -->
  <listener>
      <listener-class>com.exp.listener.MyServletContextListener</listener-class>
  </listener>
  
  <!-- 配置一个Session监听器  -->
  <listener>
      <listener-class>com.exp.listener.MyHttpSessionListener</listener-class>
  </listener>
  
  <!-- 配置filter过滤器  -->
  <filter>
      <filter-name>myFilter</filter-name>
      <filter-class>com.exp.filter.MyFilter</filter-class>
  </filter>
  
  <!-- 配置过滤器拦截的路径 -->
  <filter-mapping>
      <filter-name>myFilter</filter-name>
      <!-- 只拦截后缀是.jsp的路径 -->
      <url-pattern>*.jsp</url-pattern>
      <!-- 拦截所有的路径 -->
      <!-- <url-pattern>/*</url-pattern> -->
  </filter-mapping>
  
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>