模拟spring的注入和读取配置文件(ApplicationContext.xml)

Spring的配置文件(applicationContext.xml)

<?xml version="1.0" encoding="UTF-8"?>

<beans>

<bean id="v" class="tfq.factory.spring.Tain">

</bean>

</beans>

//Bean工厂接口

public interface BeanFactory {

Object getBean(String id);

}

注意要导入spring的jar包和jdom的jar包！

import java.io.IOException;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.jdom.Document;

import org.jdom.Element;

import org.jdom.JDOMException;

import org.jdom.input.SAXBuilder;

import org.jdom.xpath.XPath;

public class ClassPathXmlApplicationContext implements BeanFactory {

/**

* Spring容器概念

*/

private Map<String,Object> container=new HashMap<String,Object>();

public ClassPathXmlApplicationContext(String fileName)

throws JDOMException, IOException,

InstantiationException, IllegalAccessException,

ClassNotFoundException {

//实例化一个读取Xml文件对象实例

SAXBuilder sb = new SAXBuilder();

//获取配置文件对象

Document doc = sb.build(this.getClass().getClassLoader()

.getResourceAsStream(fileName));

//获取配置文件中的根节点

Element root = doc.getRootElement();

//获取根节点的子节点

List list = XPath.selectNodes(root, "/beans/bean");

System.out.println(list.size());

//遍历获取的子节点

for (int i = 0; i < list.size(); i++) {

//获取配置文件中的第i个bean节点

Element bean = (Element) list.get(i);

//获取配置文件中的第i个bean节点的ID

String id = bean.getAttributeValue("id");

//获取配置文件中的第i个bean节点class

String cla = bean.getAttributeValue("class");

//获取配置文件中的第i个bean节点class转换成Object

Object o=Class.forName(cla).newInstance();

container.put(id, o);

System.out.println(id + " " + cla);

}

}

@Override

public Object getBean(String id) {

return container.get(id);

}

}

import tfq.factory.spring.Moveable;

public class Car implements Moveable{

@Override

public void run(){

System.out.println("Car drive....");

}

}

import java.io.IOException;

import java.util.Properties;

import org.jdom.JDOMException;

public class TestSpring {

public static void main(String[] args) throws ClassNotFoundException,

JDOMException, IOException, InstantiationException, IllegalAccessException{

BeanFactory f=(BeanFactory)new

ClassPathXmlApplicationContext("tfq/factory/spring/applicationContext.xml");

Object o=f.getBean("v");

Moveable m=(Moveable)o;

m.run();

}

}

输出:

1

v tfq.factory.spring.Car

Car drive