Spring--Bean的作用域

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作用域 

•       singleton：（默认 ）单例，在一个bean容器中只存在一份 
•       prototype：每次请求（每次使用）创建新的实例，destory方式不生效 
•       request：每次Http请求创建一个实例且仅在当前request内生效 
•       session：同上，在session内生效 
•       global session：基于portlet的Web中生效，如果在web，基于session
   

singleton作用域 

package cn.itcast.hello;

public class Hello {

}

base4.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"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans 
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop 
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx 
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context      
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
   
   <bean id="hello" class="cn.itcast.hello.Hello" scope="singleton"/>
</beans>

package cn.itcast.hello;

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

public class HelloTest {
	@Test
	public void HelloTest(){
		String xmlpath="cn/itcast/hello/beans4.xml";
		ApplicationContext context=new ClassPathXmlApplicationContext(xmlpath);
		System.out.println(context.getBean("hello"));
		System.out.println(context.getBean("hello"));
	}
}

 运行结果：

prototype作用域

   <bean id="hello" class="cn.itcast.hello.Hello" scope="singleton"/>

改为：

   <bean id="hello" class="cn.itcast.hello.Hello" scope="prototype"/>

运行结果：