有兴趣 不自卑

spring Ioc容器的关键点：
* 必须将被管理的对象定义到spring配置文件中
* 必须定义构造函数或setter方法，让spring将对象注入过来

引用

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:aop="http://www.springframework.org/schema/aop"
     xmlns:tx="http://www.springframework.org/schema/tx"
     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
          
<bean id="userDao4MySqlImpl" class="com.bjsxt.spring.dao.UserDao4MySqlImpl"/>
<bean id="userDao4OracleImpl" class="com.bjsxt.spring.dao.UserDao4OracleImpl"/>

<bean id="userManager" class="com.bjsxt.spring.manager.UserManagerImpl">

<!-- 构造方法注入
<constructor-arg ref="userDao4OracleImpl"/>
-->
<property name="userDao" ref="userDao4OracleImpl"/>
</bean>

</beans>

   
Client.java

package com.bjsxt.spring.client;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.bjsxt.spring.dao.UserDao4MySqlImpl;
import com.bjsxt.spring.dao.UserDao4OracleImpl;
import com.bjsxt.spring.manager.UserManager;
import com.bjsxt.spring.manager.UserManagerImpl;

public class Client {

	public static void main(String[] args) {
		//UserManager userManager = new UserManagerImpl(new UserDao4OracleImpl());
//		UserManager userManager = new UserManagerImpl(new UserDao4MySqlImpl());
//		userManager.save("张三", "123");
		
		BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml");
		
		UserManager userManager = (UserManager)factory.getBean("userManager");
		userManager.save("张三", "123");
		
//		UserManagerImpl userManager = new UserManagerImpl();
//		userManager.setUserDao(new UserDao4MySqlImpl());
//		userManager.save("张三", "123");
	}
}