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）

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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{@Overridepublic 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();
}