Spring bean执行顺序

Question

public abstract class ClassA {
    private String text;

    public ClassA(){
        System.out.println("- new -");
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

}

public class ClassB extends ClassA {
    public void settings(){
        System.out.println("Constructing ClassB object");
    }
}

public class ClassC {
    private List<ClassA> items = new ArrayList<>();

    public List<ClassA> getItems(){
        return items;
    }

    public void setItems(List<ClassA> items) {
        this.items = items;
    }

    public void print(){
        String s = "This object contains: ";
        for(ClassA item : items){
            s+= item.getText();
        }
        System.out.println(s);
    }
}

类D

public class ClassD extends ClassA {
    public void settings(){
        System.out.println("Constructing ClassD Object");
    }
}

主要方法是

public class Question1Application {

    public static void main(String[] args) {
        //SpringApplication.run(Question1Application.class, args);
        System.out.println("PREPARE");
        ConfigurableApplicationContext context = new      ClassPathXmlApplicationContext("springconfig.xml");
        System.out.println("BEGIN");
        ClassB classB = context.getBean("objectB",ClassB.class);
        ClassC classC = context.getBean("objectF",ClassC.class);
        System.out.println("END");
        context.close();
    }
}

Bean配置文件是

?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

<bean id="objectA" class="com.example.ClassA" abstract="true">
    <property name="text" value="Things!"></property>
</bean>

<bean id="objectB" class="com.example.ClassB" scope="prototype" parent="objectA"
    init-method="settings">
</bean>

<bean id="objectC" class="com.example.ClassD" scope="prototype" parent="objectA"
    init-method="settings">
</bean>

<bean id="objectD" class="com.example.ClassD" lazy-init="true" parent="objectA"
    init-method="settings">
</bean>

<bean id="objectE" class="com.example.ClassD" parent="objectA" init-method="settings"></bean>

<bean id="objectF" class="com.example.ClassC" init-method="print">
    <property name="items">
        <list>
            <ref bean="objectB"></ref>
            <bean class="com.example.ClassB">
                <property name="text" value="lot of things!"></property>
            </bean>
        </list>
    </property>
</bean>

程序的输出为：

PREPARE
-new-
constructing classD object
-new-
constructing classB object
-new-
This object contains : lots of things!
BEGIN
-new-
constructing classB object
END

Answer 1

该示例很好地演示了单例范围和原型范围之间的区别。

第一个实例将在上下文启动时立即创建，并且IOC控制器应该支持它们的整个生命周期。

与单例相比，对于原型范围，容器将根据我们的需求创建一个实例。一个请求-从上下文创建一个新的配置良好的对象。一个容器是不会处理这种类型的豆子的，在送人之后就不再去想它们了。

null