spring5.0学习笔记3

BeanFactory和ApplicationContext的区别
ApplicationContext 立即加载，读取完配置文件后立即创建配置文件中的对象
BeanFactory 延迟加载，什么时候根据id获取对象，什么时候才创建对象

三种创建bean的方式

<?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:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
<!-- 把创建对象交给spring管理 -->
<!-- 1.使用bean标签创建 ，使用默认构造函数创建
<bean id="accountServerice" class="com.test.AccountServiceImp"></bean>-->
<!-- 使用普通工厂中的方法创建对象
<bean id="instanceFactory" class="com.test.IntanceFactory"></bean>
<bean id="accountService" factory-bean="instanceFactory"" factory-method="getAccountService"></bean> -->
<!-- 使用工厂中的静态方法 -->
<bean id="accountService" class="com.test.StaticFactory" factory-method="getAccountService"/>
</beans>

/*** bean的三种创建方式*/
package com.test;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** 模拟一个表现层，用户调用业务层* @author Administrator**//*** 获取spring的IOC核心容器* ApplicationContext的三个常用实现类*  ClassPathXmlApplicationContext：可以加载类路径下的配置文件  常用*    FileSystemXmlApplicationContext:加载任意磁盘下的配置文件，必须有访问权限*    AnnotationConfigApplicationContext:用于读取注解创建容器的*/
public class Test{public static void main(String[] args){//1.获取核心容器对象ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");//2.根据id获取bean对象IAccountService as = (IAccountService)ac.getBean("accountService");System.out.println(as);}
}
/*** 创建bean对象的工厂* Bean 在计算机术语中，含义为可重用组件* JavaBean，用java语言编写的可重用组件*        JavaBean >实体类*       具体到项目中，就是service和dao对象*      第一个：配置一个文件来配置service和dao，配置的内容是唯一标识的权限定内名*        第二个：通过读取配置文件内容，反射创建对象* *      配置文件可以是propertie也可以使xml*/class IntanceFactory{public IAccountService getAccountService(){return new AccountServiceImp();}
}class StaticFactory{public static IAccountService getAccountService(){return new AccountServiceImp();}
}interface IAccountService{/*** 模拟保存账户*/public void saveAccount();
}/*** 业务层实现类*/
class AccountServiceImp implements IAccountService{public void saveAccount(){System.out.println("save a account");}
}

Bean的作用范围

singleton 单例
prototype 多例
request 作用于web应用的request范围
session 作用于web应用的session范围
global 作用于集群环境的会话范围

Bean的生命周期

singleton 容器创建时对象出生
容器在，对象在
容器亡，对象亡

prototype 第一次使用对象出生
，使用对象过程中一直活着，垃圾回收器回收

<?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:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
<!-- 把创建对象交给spring管理 -->
<!-- 1.使用bean标签创建 ，使用默认构造函数创建 -->
<bean id="accountService" class="com.test.AccountServiceImp"scope="singleton" init-method="init" destroy-method="destroy"></bean>
</beans>

/*** bean生命周期*/
package com.test;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** 模拟一个表现层，用户调用业务层* @author Administrator**//*** 获取spring的IOC核心容器* ApplicationContext的三个常用实现类*  ClassPathXmlApplicationContext：可以加载类路径下的配置文件  常用*    FileSystemXmlApplicationContext:加载任意磁盘下的配置文件，必须有访问权限*    AnnotationConfigApplicationContext:用于读取注解创建容器的*/
public class Test{public static void main(String[] args){//1.获取核心容器对象ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");//2.根据id获取bean对象IAccountService as = (IAccountService)ac.getBean("accountService");System.out.println(as);as.saveAccount();//手动关闭容器ac.close();}
}interface IAccountService{/*** 模拟保存账户*/public void saveAccount();
}/*** 业务层实现类*/
class AccountServiceImp implements IAccountService{public AccountServiceImp(){System.out.println("accountService对象创建了");}public void init(){System.out.println("对象初始化了");}public void destroy(){System.out.println("对象销毁了");}public void saveAccount(){System.out.println("save a account");}
}

2020-3-24 22:11:24 org.springframework.context.support.AbstractApplicationContext prepareRefresh 信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1ef9f1d: display name [org.springframework.context.support.ClassPathXmlApplicationContext@1ef9f1d]; startup date [Tue Mar 24 22:11:24 CST 2020]; root of context hierarchy 2020-3-24 22:11:24 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 信息: Loading XML bean definitions from class path resource [bean.xml] 2020-3-24 22:11:25 org.springframework.context.support.AbstractApplicationContext obtainFreshBeanFactory 信息: Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@1ef9f1d]: org.springframework.beans.factory.support.DefaultListableBeanFactory@1175422 2020-3-24 22:11:25 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons 信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1175422: defining beans [accountService]; root of factory hierarchy accountService对象创建了对象初始化了 com.test.AccountServiceImp@102799c save a account 2020-3-24 22:11:25 org.springframework.context.support.AbstractApplicationContext doClose 信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1ef9f1d: display name [org.springframework.context.support.ClassPathXmlApplicationContext@1ef9f1d]; startup date [Tue Mar 24 22:11:24 CST 2020]; root of context hierarchy 2020-3-24 22:11:25 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons 信息: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1175422: defining beans [accountService]; root of factory hierarchy 对象销毁了