package InstancePackage;

public class Person {
    int age;

    Son son;

    public Son getSon() {
        return son;
    }

    public void setSon(Son son) {
        this.son = son;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}
 

package InstancePackage;

public class Son {
    int age;

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

package TestPackage;

import InstancePackage.Person;
import InstancePackage.Son;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringTest {
    public static void main(String []args){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Son son = applicationContext.getBean("son1", Son.class);
        System.out.println(son.getAge());


        Son son1 = applicationContext.getBean("son2", Son.class);
        System.out.println(son1.getAge());

        int  age1 = applicationContext.getBean("theAge", Integer.class);
        System.out.println(age1);

        int age2 = applicationContext.getBean("theAge2", Integer.class);
        System.out.println(age2);
    }
}
 

<?xml version="1.0" encoding="GBK"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">


    <!--這個是一個普通的bean-->
    <bean id="person" class="InstancePackage.Person">
        <property name="age" value="31"/>
        <property name="son">
            <bean class="InstancePackage.Son">
                <property name="age" value="10"/>
            </bean>
        </property>
    </bean>

<!--這裡將class指定為PropertyPathFactoryBean,然後呢，用targetBeanName指定要獲取哪一個bean的屬性
用propertyPath指定要獲取它的哪一個屬性，就ok-->
    <bean id="son1" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
        <property name="targetBeanName" value="person"/>
        <property name="propertyPath" value="son"/>
    </bean>

<!--這個呢它的實現類是一個son，但是它的age屬性id為person.son.age，表示是要獲取person的son的
age屬性值，當然啦class是PropertyPathFactoryBean-->
 <bean id="son2" class="InstancePackage.Son">
     <property name="age" >
         <bean id="person.son.age"
               class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
     </property>
 </bean>

<!--這裡呢是最終是一個int，因為它的目標是person下的son的age-->
    <bean id="theAge" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
        <property name="targetBeanName" value="person"/>
        <property name="propertyPath" value="son.age"/>
    </bean>


    <!--這裡是自己定義了一個目標bean，然後獲取它的age-->
    <bean id="theAge2" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
        <property name="targetObject">
            <bean class="InstancePackage.Person">
                <property name="age" value="30"/>
            </bean>
        </property>

        <property name="propertyPath" value="age"/>
    </bean>

</beans>
 

這是我看李剛編著的《輕量級javaEE企業應用實戰（第五版）-Struts2+Spring5+Hibernate5/JAP2》後總結出來的。