林炳文Evankaka原创作品。转载请注明出处http://blog.csdn.net/evankaka
本文主要讲了Spring中Bean之间的关系，分为继承、依赖和引用三个类型。文章中都分别有例子和用法分析。
使用案例：
定义House.java:
package com.mucfc;
public class House {
private String houseSize;
private String housePosition;
private String housePrice;
public String getHouseSize() {
return houseSize;
}
public void setHouseSize(String houseSize) {
this.houseSize = houseSize;
}
public String getHousePosition() {
return housePosition;
}
public void setHousePosition(String housePosition) {
this.housePosition = housePosition;
}
public String getHousePrice() {
return housePrice;
}
public void setHousePrice(String housePrice) {
this.housePrice = housePrice;
}
public String toString(){
return "房子大小："+houseSize+" 房子位置："+housePosition+" 房子价格："+housePrice;
}
}
如果多个bean存在相同的配置信息，Spring允许我们定义一个父，子将自动继承父的配置信息。
<!-- 定义抽象bean -->
<bean id="abstracthouse" class="com.mucfc.House" p:houseSize="150坪"
p:housePosition="科苑花园" p:housePrice="15万"/>
<!-- 继承于abstracthouse -->
<bean id="house2" parent="abstracthouse" p:housePosition="汇景苑"/>
<!-- 继承于abstracthouse -->
<bean id="house3" parent="abstracthouse" p:housePrice="8万"/>使用： House house5=applicationContext.getBean("house2",House.class);
House house6=applicationContext.getBean("house3",House.class);
System.out.println(house5);
System.out.println(house6);输出结果：房子大小：150坪 房子位置：汇景苑 房子价格：15万
房子大小：150坪 房子位置：科苑花园 房子价格：8万
house1跟house2都继承自abstracthouse,Spring会将父bean的配置信息传递给子bean，如果子bean提供了父bean已有的配置信息，那么子bean的会覆盖父bean的.
父bean的功能主要是为了简化子bean的配置，所以一般声明为abstract=“true”，表示这个不实例化为一个对应的Bean，如果用户不指定该属性为true，那么IOC容器会实例化一个名叫abstractcar的Bean。
<bean id="buyHouser" class="com.mucfc.depend.BuyHouser" />
<bean id="HouseAgent" class="com.mucfc.depend.HouseAgent" depends-on="buyHouser" /> <bean id="HouseAgent" class="com.mucfc.depend.HouseAgent" init-method="initHouseAgent" depends-on="buyHouser,sellHouser" />例子中使用了‘depends-on‘来表达对多个bean的依赖。
<bean id="buyHouser" class="com.mucfc.depend.BuyHouser" lazy-init="true"/>
<bean id="sellHouser" class="com.mucfc.depend.SellHouser" /> 当ApplicationContext实现加载上述配置时，设置为lazy的bean-buyHouser将不会在ApplicationContext启动时提前被实例化，而not.lazy--sellHouser却会被提前实例化。package com.mucfc.depend;
public class BuyHouser {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void initBuyHouser(){
System.out.println("初始化了BuyHouser");
}
}
2、卖房人SellHouser.javapackage com.mucfc.depend;
public class SellHouser {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void initSellHouser (){
System.out.println("初始化了SellHouser ");
}
}
3、房屋中介HouseAgent.javapackage com.mucfc.depend;
public class HouseAgent {
private BuyHouser buyHouser;
private SellHouser sellHouser;
public BuyHouser getBuyHouser() {
return buyHouser;
}
public void setBuyHouser(BuyHouser buyHouser) {
this.buyHouser = buyHouser;
}
public SellHouser getSellHouser() {
return sellHouser;
}
public void setSellHouser(SellHouser sellHouser) {
this.sellHouser = sellHouser;
}
public void initHouseAgent(){
System.out.println("初始化了HouseAgent");
}
}
4、beans.xml<?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"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<bean id="houseAgent" class="com.mucfc.depend.HouseAgent" init-method="initHouseAgent" depends-on="buyHouser,sellHouser" />
<bean id="buyHouser" class="com.mucfc.depend.BuyHouser" init-method="initBuyHouser" lazy-init="true"/>
<bean id="sellHouser" class="com.mucfc.depend.SellHouser" init-method="initSellHouser" lazy-init="true"/>
</beans>
5、测试package com.mucfc.depend;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
ApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml");
}
}
结果：
<bean id="houseAgent1" class="com.mucfc.depend.HouseAgent" p:buyHouser="buyHouser" p:sellHouser="sellHouser"/> <bean id="houseAgent2" class="com.mucfc.depend.HouseAgent" p:buyHouser-ref="buyHouser" p:sellHouser-ref="sellHouser"/>或写成
<bean id = "houseAgent3" class = "com.mucfc.depend.HouseAgent" >
<property name="buyHouser">
<ref bean="buyHouser"/>
</property>
<property name="sellHouser">
<ref local="sellHouser"/>
</property>
</bean> <ref local="xx"/> 原文地址：http://blog.csdn.net/evankaka/article/details/45023835
