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"?>

  aop2
  
  
  
  
      oneFilter
      class>com.xzit.aop.OneFilterclass>
      
          ip
          127.0.0.1
      
  
  
  
  
      oneFilter
      /*
  
  
  
      twoFilter
      com.xzit.aop.TwoFilter
  
  
  
  
      twoFilter
      /*
  
  
  
    index.jsp
  

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>


    
        
        
    
    
        index.jsp 页面