LittleRain

chapter2：
package com.apress.prospring.ch2;

import java.io.FileInputStream;
import java.util.Properties;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader;

public class HelloWorldWithDI {

    public static void main(String[] args) throws Exception {
        //get BeanFactory
        BeanFactory factory=getBeanFactory();
       
        MessageRenderer mr=(MessageRenderer)factory.getBean("renderer");
        mr.render();
    }
   
    private static BeanFactory getBeanFactory() throws Exception {
       
        // get the bean factory
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();

        // create a definition reader
        PropertiesBeanDefinitionReader rdr = new PropertiesBeanDefinitionReader(
                factory);

        // load the configuration options
        Properties props = new Properties();
        props.load(new FileInputStream("./ch2/src/conf/beans.properties"));

        rdr.registerBeanDefinitions(props);

        return factory;
    }

}

beans.properties:
renderer.class=com.apress.prospring.ch2.StandardOutMessageRenderer
renderer.messageProvider(ref)=provider

provider.class=com.apress.prospring.ch2.HelloWorldMessageProvider

DefaultListableBeanFactory负责从properties文件读取BeanFactory的配置信息，然后返回已配置的实例。
这个配置文件已经定义了DI关系，所以在main方法中无需设置MessageRenderer 和MessageProvider的依赖关系。