spring-bean配置信息重用(继承)和bean创建顺序是什么以及bean 对象的单例和多例讲解

<!--配置Monster对象-->
    <bean id="monster10" class="com.spring.bean.Monster">
        <property name="monsterId" value="10"/>
        <property name="name" value="蜈蚣精"/>
        <property name="skill" value="蜇人"/>
    </bean>
    <!--
    解读
    1. 配置Monster对象
    2.但是这个对象的属性值和 id="monster10"对象属性一样
    3.parent="monster10" 指定当前这个配置的对象的属性值从 id=monster10的对象来
    -->
    <bean id="monster11"
          class="com.spring.bean.Monster"
          parent="monster10"/>
<!-- 当我们把某个bean设置为abstract="true" 这个bean只能被继承，而不能实例化了-->
    <bean id="monster12" class="com.wyxedu.spring.beans.Monster" abstract="true">
            <property name="monsterId" value="12"/>
            <property name="name" value="美女蛇"/>
            <property name="skill" value="吃人"/>
    </bean>
<!-- parent="monster12" 就是继承使用了monster12 的配置信息-->
<bean id="monster13" class="com.wyxedu.spring.beans.Monster"
parent="monster12"/>

//配置Bean通过继承
    @Test
    public void getBeanByExtends() {
        ApplicationContext ioc =
                new ClassPathXmlApplicationContext("beans.xml");
        Monster monster11 = ioc.getBean("monster11", Monster.class);
        System.out.println("monster11=" + monster11);
        Monster monster13 = ioc.getBean("monster13", Monster.class);
        System.out.println("monster13=" + monster13);
    }

<bean id="student01" class="com.hspedu.bean.Student" />
<bean id="department01" class="com.hspedu.bean.Department" />

<bean id="student01" class="com.hspedu.bean.Student" depends-on="department01"/>
<bean id="department01" class="com.hspedu.bean.Department" />

public class Car {
    private Integer id;
    private String name;
    private Integer price;
    public Car(Integer id, String name, Integer price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
    public Car() {
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getPrice() {
        return price;
    }
    public void setPrice(Integer price) {
        this.price = price;
    }
    @Override
    public String toString() {
        return "Car{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}

<!--配置Cat对象
        1. 在默认情况下 scope属性是 singleton
        2. 在ioc容器中, 只要有一个这个bean对象
        3. 当程序员执行getBean时, 返回的的是同一个对象
        4. 如果我们希望每次getBean返回一个新的Bean对象，则可以scope="prototype"
        5. 如果bean的配置是 scope="singleton" lazy-init="true" 这时,ioc容器就不会提前创建该对象
           , 而是当执行getBean方法的时候，才会创建对象
    -->
    <bean id="cat" class="com.spring.bean.Cat" scope="prototype" lazy-init="false">
        <property name="id" value="100"/>
        <property name="name" value="小花猫"/>
    </bean>

@Test
    public void testBeanScope() {
        ApplicationContext ioc =
                new ClassPathXmlApplicationContext("beans.xml");
        Cat cat = ioc.getBean("cat", Cat.class);
        Cat cat2 = ioc.getBean("cat", Cat.class);
        Cat cat3 = ioc.getBean("cat", Cat.class);
        System.out.println("cat=" + cat);
        System.out.println("cat2=" + cat2);
        System.out.println("cat3=" + cat3);
    }