(三)配置bean之间的关系：继承、依赖

第一步：建三个类Address.java、Car.java 、Person

第二步配置文件：

<?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:p="http://www.springframework.org/schema/p"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">    <!--         抽象bean:bean的abstract属性为true,这样的bean不能被IOC容器实例化，只用来被继承配置         若某一个bean的class属性没有指定，该bean必须是一个抽象bean    -->    <bean id="address" class="com.atguigu.spring.beans.autowire.Address"          p:city="Beijing" p:street="WuDaoKou" abstract="true"></bean>    <!--         <bean id="address2" class="com.atguigu.spring.beans.autowire.Address"        p:city="Beijing" p:street="DaZhongSi"></bean>     -->    <!--bean配置的继承：使用bean的parent属性指定继承哪个bean的配置  -->    <bean id="address2" parent="address"></bean>    <bean id="address3" p:street="DaZhongSi" parent="address2"></bean>     <!--         要求配置Person時，必須有一个关联的car,换句话说这个bean依赖于car这个bean         Spring允许用户通过depends-on属性设定Bean前置依赖bean，前置依赖bean会在本bean实例化前创建好     -->    <bean id="car" class="com.atguigu.spring.beans.autowire.Car"         p:brand="Audi" p:price="300"></bean>    <bean id="person" class="com.atguigu.spring.beans.autowire.Person"         p:name="Tom" p:address-ref="address3" depends-on="car">     </bean></beans>

第三步：运行main方法

package com.atguigu.spring.beans.relation;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.atguigu.spring.beans.autowire.Address;import com.atguigu.spring.beans.autowire.Person;/** *  * 配置bean的继承和依赖 * */public class Main {    public static void main(String[] args) {        ApplicationContext ctx=new ClassPathXmlApplicationContext("beans-relation.xml");        Address address=(Address) ctx.getBean("address2");        System.out.println(address);         address=(Address) ctx.getBean("address3");        System.out.println(address);         Person person=(Person) ctx.getBean("person");        System.out.println(person);//Person [name=Tom, address=Address [city=Beijing, street=DaZhongSifangxinde], car=null]    }}

第四步：运行结果

Car's Constructor.....Address [city=Beijing, street=WuDaoKou]Address [city=Beijing, street=DaZhongSi]Person [name=Tom, address=Address [city=Beijing, street=DaZhongSi], car=null]