IOC Inverse of Control
把创建对象的控制权交给工厂
Spring基于XML的IOC环境搭建和入门
<?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.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://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 -->
<bean id="accountServerice" class="com.test.AccountServiceImp"></bean>
<bean id="accountDao" class="com.test.AccountDaoImp"></bean>
</beans>
/**
* ioc
*/
package com.test;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
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("accountServerice");
IAccountDao adao = (IAccountDao)ac.getBean("accountDao");
System.out.println(as);
System.out.println(adao);
}
}
/**
* 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 BeanFactory{
private static Properties props;
//定义个Map,用于存放创建的对象,称之为容器
private static Map<String, Object> beans;
static{
try {
//实例化对象
props=new Properties();
//InputStream in=new FileInputStream();
//获取properties文件的流对象
InputStream in = BeanFactory.class.getClassLoader().getResourceAsStream("bean.properties");
props.load(in);
//实例化容器
beans = new HashMap<String, Object>();
//取出配置文件中所有的key
Enumeration<Object> keys = props.keys();
//遍历枚举
while(keys.hasMoreElements()){
//取出key
String key = keys.nextElement().toString();
//根据key获取value
String beanPath = props.getProperty(key);
//反射创建对象
Object value = Class.forName(beanPath).newInstance();
//把key-value存入容器中
beans.put(key, value);
}
} catch (Exception e) {
// TODO: handle exception
throw new ExceptionInInitializerError("初始化properties失败");
}
}
/**
* 根据bean名称获取bean对象,单例
* @param beanName
* @return
*/
public static Object getBean(String beanName){
return beans.get(beanName);
}
/*
public static Object getBean(String beanName){
Object bean = null;
try {
String beanPath=props.getProperty(beanName);
System.out.println(beanPath);
bean=Class.forName(beanPath).newInstance();//每次都会调用默认构造函数创建对象
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
return bean;
}
*/
}
interface IAccountService{
/**
* 模拟保存账户
*/
void saveAccount();
}
/**
* 业务层实现类
*/
class AccountServiceImp implements IAccountService{
//private IAccountDao accountDao=new AccountDaoImp();
private IAccountDao accountDao = (IAccountDao)BeanFactory.getBean("accountDao");
private int i=1;
public void saveAccount(){
System.out.println(accountDao);
accountDao.saveAccount();
System.out.println(i);
i++;
}
}
/**
* 账户的持久层接口
*/
interface IAccountDao{
/**
* 模拟保存账户
*/
void saveAccount();
}
/*
* 账户的持久层实现类,若没有编译器也不会报错
*/
class AccountDaoImp implements IAccountDao{
public void saveAccount(){
System.out.println("保存了账户");
}
}
2020-3-24 21:21:17 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 21:21:17 CST 2020]; root of context hierarchy
2020-3-24 21:21:17 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [bean.xml]
2020-3-24 21:21:18 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 21:21:18 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1175422: defining beans [accountServerice,accountDao]; root of factory hierarchy
com.test.AccountServiceImp@1d6f122
com.test.AccountDaoImp@7109c4
com.test.AccountDaoImp@1385660
保存了账户