Car.java
package com.gong.spring.beans.autowire; public class Car { public Car() { } public Car(String name) { this.name = name; } private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Car [name=" + name + "]"; } }
beans-scope.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="car" class="com.gong.spring.beans.autowire.Car" p:name="baoma"></bean> </beans>
Main.java
package com.gong.spring.beans.autowire; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { //1.创建spring的IOC容器对象 ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-scope.xml"); //2.从容器中获取Bean实例 Car car = (Car) ctx.getBean("car"); Car car2 = (Car) ctx.getBean("car"); System.out.println(car == car2); System.out.println(car.toString()); } }
输出:
默认情况下,在xml文件中配置的bean都是单例模式,即实例化这个相同类型的bean时,返回的是同一个对象,即实例化IOC容器ctx时,就已经创建好了一个唯一的bean。我们可以在xml中设置scope属性的值来改变bean的作用域。
<bean id="car" class="com.gong.spring.beans.autowire.Car" p:name="baoma" scope="prototype"></bean>
scope有四种值:
默认的就是singleleton,在指定为prototype之后,每次实例化的对象就不是同一个bean了。