Spring的singleton模式

Compnay类

package ioc.demo;

public class Company {
	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
}

Spring的applicationContext.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:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
   
	<bean id="company" class="ioc.demo.Company">
		<property name="name" value="enrising"/>
	</bean>
</beans>

运行的Demo：

package ioc.demo;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Demo {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext(
				"applicationContext.xml");
		Company c = (Company)context.getBean("company");
		c.setName("Intasect");
		Company c2 = (Company)context.getBean("company");
		System.out.println(c2.getName());
	}
}

运行结果：Intasect

将Demo类修改一下：

package ioc.demo;

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

public class Demo {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext(
				"applicationContext.xml");
		Company c = (Company)context.getBean("company");
		c.setName("Intasect");
		
		ApplicationContext context2 = new ClassPathXmlApplicationContext(
		"applicationContext.xml");
		Company c2 = (Company)context2.getBean("company");
		System.out.println(c2.getName());
	}
}

运行结果：enrising

比较两次运行结果，得出结论：同一个ApplicationContext，两次getBean()取得的是同一个对象的引用。不同的ApplicationContext，两次getBean()取得的是不同的对象。