Helloworld之Spring依赖注入/控制反转(DI/IoC)版

package cn.dennishucd;

public interface MessageService {
	public String getMessage();
}

package cn.dennishucd;

public class MessageServiceImpl implements MessageService {
	@Override
	public String getMessage() {
		return "Hello World!";
	}
}

package cn.dennishucd;

public class MessagePrinter {
	final private MessageService service;
	
	public MessagePrinter(MessageService service) {
		this.service = service;
	}
	
	public void printMessage() {
		System.out.println(this.service.getMessage());
	}
}

package cn.dennishucd;

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

public class HelloworldSpring {

	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("helloworld.xml");
		MessagePrinter printer = (MessagePrinter) context.getBean("printer");
		
		printer.printMessage();
		
		((ClassPathXmlApplicationContext)context).close();
	}
}

<?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"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans        
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context                
        http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    
    <bean id="service" class="cn.dennishucd.MessageServiceImpl"/>
    
    <bean id="printer" class="cn.dennishucd.MessagePrinter">
     <constructor-arg ref="service"/>
    </bean>
</beans>