Spring Framework: understood as it is to create a managed object, dependent on the container destroyed.

　　

DAO--------->Service------>Controller.

 DAO: specifically interact with the database .

MySqlDao . Mysql database interaction

OraclaDao. Oracle database.

 Service:

// MysqlDao mdao = new MysqlDao () ; // think there are no disadvantages. hardcode. Poor scalability.

OracleDao odao = new OracleDao (); // how to solve. = 1. The left side of the interface may be used

　　

Spring steps created .

 

1. Add dependency.

 

 

1. Participation in a configuration file. applicationContext.xml

 

 

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
 5 
 6     <bean id="mysql" class="com.zhiyou100.wc.dao.MysqlDao"/>
 7     <bean id="oracle" class="com.zhiyou100.wc.dao.OracleDao " . 8/>
         
 9     <bean id="s" class="com.zhiyou100.wc.service.Service">
10         <property name="mdao" ref="mysql"></property>
11     </bean>
12     
13     
14 </beans>

1. test.

 

 

 1 package com.zhiyou100.wc.test;
 2 
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5 
 6 import com.zhiyou100.wc.service.Service;
 7 
 8 public class Test {
 9     
10     public static void main(String[] args) {
11         //Service service=new Service();
12         
13         ApplicationContext app=new ClassPathXmlApplicationContext("applicationContext.xml");
14         
15         Service s=(Service) app.getBean("s");
16         s.show();
17         
18     }
19 
20 }