SpringIOC_对象的多实例和单实例

<?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-2.5.xsd"> 
<bean id="helloWorld" class="com.spring.scope.HelloWord"></bean>

<bean id="helloWorld2" class="com.spring.scope.HelloWord"
scope="prototype"></bean>

</beans>

package com.spring.scope;

public class HelloWord {

public HelloWord(){

System.out.println("create Object");
}

public void hello(){
System.out.println("hello word!");
}

}

package com.spring.scope.test;

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

import com.spring.scope.HelloWord;

public class HelloWordTest {

/**
*
*在Spring容器中的对象，默认情况下是单例的
*    因为对象是单列的,所以只要在类上声明一个属性，该属性含有数据，那么这个该属性将是全局的 (危险)
*/
@Test
public void testScope_Default(){

//启动Spring容器
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");

//根据id把Spring容器中的bean提取出来
HelloWord helloWord = (HelloWord) context.getBean("helloWorld");
HelloWord helloWord2 = (HelloWord) context.getBean("helloWorld");

System.out.println(helloWord);
System.out.println(helloWord2);
//create Object
//com.spring.scope.HelloWord@29a3a9db
//com.spring.scope.HelloWord@29a3a9db

}

/**
*
* 如果scope为prototype，Spring容器产生的对象就是多例
*
* 如果一个对象为多例，这个对象在Spring容器中创建时机就会发生改变，则不会再启动的时候创建对象,会再getBean()才创建对象
*  即:
*   如果scope为prototype，则无论Lazy-init为什么值，都是在 context.getBean()时创建对象。
*
*/
@Test
public void testScope_Prototype(){
//启动Spring容器
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");

//根据id把Spring容器中的bean提取出来
HelloWord helloWord = (HelloWord) context.getBean("helloWorld2");
HelloWord helloWord2 = (HelloWord) context.getBean("helloWorld2");

System.out.println(helloWord);
System.out.println(helloWord2);

/* create Object
create Object
com.spring.scope.HelloWord@79d0e2d2
com.spring.scope.HelloWord@db8779    */

}

}