Spring的Bean详解=Bean别名+作用范围+使用场景

目录

Bean的别名：id和name的地位等同

 Bean的作用范围：scope单例与非单例

 Bean的使用场景：什么时候交给容器？什么时候不交？​

 Bean的别名实践（含代码）

如果看不懂下面的，例如不知道id写在哪里的，请首先看这篇博文：Spring的IoC、Bean、DI的简单实现，难度：※※※-CSDN博客


 

Bean的别名：id和name的地位等同

 Bean的作用范围：scope单例与非单例

 Bean的使用场景：什么时候交给容器？什么时候不交？

 Bean的别名实践（含代码）

案例一：

 案例二：

<?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="cat" class="org.example.package2.Cat"/>
    <bean id="dog" class="org.example.package2.Dog"/>
    <bean id="animalSet" name="abc1234" class="org.example.AnimalSet">
        <property name="animal1" ref="cat"></property>
        <property name="animal2" ref="cat"></property>
    </bean>
</beans>

package org.example;


import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {
    public static void main(String[] args) {
        ApplicationContext iocContext = new ClassPathXmlApplicationContext("applicationConfig.xml");
        AnimalSet animalSet = (AnimalSet) iocContext.getBean("abc1234");
        System.out.println(animalSet);
        animalSet.animalSetSound();

    }
}

package org.example;

import org.example.package1.Animal;

public class AnimalSet{
    Animal animal1;
    Animal animal2;

    public void animalSetSound(){
        animal1.sound();
        animal2.sound();
    }

    public void setAnimal1(Animal animal1) {
        this.animal1 = animal1;
    }
    public void setAnimal2(Animal animal2) {
        this.animal2 = animal2;
    }

}

package org.example.package2;
import org.example.package1.Animal;

public class Cat implements Animal{
    @Override
    public void sound(){
        System.out.println("cat sound");
    }
}

package org.example.package2;

import org.example.package1.Animal;

public class Dog implements Animal {
    public void sound() {
        System.out.println("dog sound");
    }
}

package org.example.package1;

public interface Animal {
    void sound();
}