AOP编程模式

一句话概括：

AOP的编程模式就是使用filter拦截请求，分离主流业务和子业务。

比如filter可以拦截重复登录的请求。就像你想去见公司的大BOSS，可能要经过门卫，前台，秘书等层层拦截。filter也可以串联的多层拦截，满足一层以后到下一层。

package com.xzit.aop;

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 OneFilter implements Filter {

    private String ip = "";
    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        System.out.println("释放资源");
    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("执行过滤");
//        if(ip.equals("127.0.0.1")) {
//            System.out.println("您被举报，暂时无法访问本网站的任何资源");
//        }else {
//            
//            chain.doFilter(arg0, arg1);    //执行链条驱动，交给下一个Filter(如果有)
//        }
        chain.doFilter(arg0, arg1);    //执行链条驱动，交给下一个Filter(如果有)

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("初始化");
        ip = arg0.getInitParameter("ip");
    }

}

package com.xzit.aop;

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 TwoFilter implements Filter {

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

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("过滤器TwoFilter");
//        chain.doFilter(arg0,arg1);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }

}

<?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_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>aop2</display-name>
  
  <!-- 配置自定义过滤器  -->
  
  <filter>
      <filter-name>oneFilter</filter-name>
      <filter-class>com.xzit.aop.OneFilter</filter-class>
      <init-param>
          <param-name>ip</param-name>
          <param-value>127.0.0.1</param-value>
      </init-param>
  </filter>
  
  <!-- 配置Filter的拦截映射 -->
  <filter-mapping>
      <filter-name>oneFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <filter>
      <filter-name>twoFilter</filter-name>
      <filter-class>com.xzit.aop.TwoFilter</filter-class>
  </filter>
  
  <!-- 配置Filter的拦截映射 -->
  <filter-mapping>
      <filter-name>twoFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Insert title here</title>
    </head>
    <body>
        index.jsp 页面
    </body>
</html>

posted @ 2022-03-09 02:07 伊万阅读(99) 评论(0) 收藏举报

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