Bean的作用域：单例与原型

Scope：实体类

package com.student.scope;

public class Scope {

}

bean4.xml ：配置文件（单例）

<?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">
	<!-- services -->
	<bean id="bean4" class="com.student.scope.Scope" scope="singleton">
	</bean>
</beans>

scopeTest：测试类

package com.student.scope;

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

import com.student.instance.constructor.Bean1;

public class ScopeTest {

	public static void main(String[] args) {
		String xmlPath = "com/student/scope/bean4.xml";
		ApplicationContext applicationContext =new ClassPathXmlApplicationContext(xmlPath);
		Scope scope1 =(Scope)applicationContext.getBean("bean4");
		Scope scope2 =(Scope)applicationContext.getBean("bean4");
		System.out.println(scope1);
		System.out.println(scope2);

	}

}

输出结果：

十月 13, 2019 5:04:32 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@46f7f36a: startup date [Sun Oct 13 17:04:32 CST 2019]; root of context hierarchy
十月 13, 2019 5:04:32 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [com/student/scope/bean4.xml]
com.student.scope.Scope@6a024a67
com.student.scope.Scope@6a024a67

修改成多例（原型）：

<?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">
	<!-- services -->
	<bean id="bean4" class="com.student.scope.Scope" scope="prototype">
	</bean>
</beans>

输出结果：

十月 13, 2019 5:10:21 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@46f7f36a: startup date [Sun Oct 13 17:10:21 CST 2019]; root of context hierarchy
十月 13, 2019 5:10:21 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [com/student/scope/bean4.xml]
com.student.scope.Scope@32e6e9c3
com.student.scope.Scope@5056dfcb

总结：1.如果不定义scope属性，系统默认是单例的，也就是同一个实体类，spring容器只能创建同一个实例。
2.prototype 原型 也叫多例，对于同一个实体类，每次生成的实例（scope1,scope2）都是不同的。