Java-马士兵设计模式学习笔记-工厂模式-用Jdom模拟Spring

 一、概述

1.目标：模拟Spring的Ioc

2.用到的知识点：利用jdom的xpath读取xml文件，反射

 

二、有如下文件：

1.applicationContext.xml

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

<beans>

  <bean id="vehicle" class="com.tong.spring.factory.Car">

  </bean>

</beans>

　　

2.BeanFactory.java

public interface BeanFactory {

	Object getBean(String id);

}

　　

3.ClassPathXmlApplicationContext.java

public class ClassPathXmlApplicationContext implements BeanFactory{

	

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



	public ClassPathXmlApplicationContext(String fileName) {

		

		//读取xml文件

		SAXBuilder sb = new SAXBuilder();

		Document doc;

		try {

			//doc = sb.build(fileName);

			//Test.java要改为BeanFactory factory = new ClassPathXmlApplicationContext("com/tong/spring/factory/applicationContext.xml");

			//否则付出现“java.net.MalformedURLException”

			doc = sb.build(this.getClass().getClassLoader().getResourceAsStream(fileName));

			Element root = doc.getRootElement();

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



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

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

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

				String clazz = element.getAttributeValue("class");



				// 利用反射生成例,然后装进容器

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

				container.put(id, o);

			}

		} catch (Exception e) {

			e.printStackTrace();

		}



	}



	@Override

	public Object getBean(String id) {

		return container.get(id);

	}



}

　　

4.Movable.java

public interface Movable {

	void run();

}

　　

5.Car.java

public class Car implements Movable {



	public void run() {

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

	}

	

}

　

6.Test.java　

 

public class Test {

	

	@org.junit.Test

	public void test() {

		

		//BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml");

		BeanFactory factory = new ClassPathXmlApplicationContext("com/tong/spring/factory/applicationContext.xml");

		Object o = factory.getBean("vehicle");

		Movable m = (Movable)o;

		m.run();

	}

}

 

　　

 

　　

运行结果：