這一節我們來看看怎麼使用Spring建立我們的Bean物件。

    容器是Spring的核心，Spring的容器有兩種型別：Bean工廠，由BeanFactory介面定義，是最簡單的容器；以及應用上下文，由ApplicationContext定義。Bean工廠對於大多數應用來說太低階了，因此應用上下文更為受歡迎。

    應用上下文又可以分為以下幾種型別：

        ClassPathXmlApplicationContext----從類路徑下的XML配置檔案載入上下文，把應用上下文定義檔案當作類資源

FileSystemXmlApplicationContext----讀取檔案系統下的XML配置檔案並載入上下文定義

XmlWebApplicationContext----讀取Web應用下的XML配置檔案並裝載上下文定義

    下面我們來應用Spring建立Bean物件，首先我們來模擬一個環境，G20峰會的晚會表演，據說很不賴，畫面直接可以做桌布

/**
 * 面向介面程式設計，表演者介面
 * @author liuyc
 *
 */
public interface Performer {
	public void perform();
}

/**
 * 歌手類
 * @author liuyc
 *
 */
@SuppressWarnings("all")
public class Singer implements Performer{
	
	private String song;
	
	private Instrument instrument;
	
	public Singer() {
	}

	public Singer(String song) {
		this.song = song;
	}
	
	public Singer(String song, Instrument instrument) {
		super();
		this.song = song;
		this.instrument = instrument;
	}

	@Override
	public void perform() {
		this.instrument.play(song);
		System.out.println("while singing ...");
	}
}
 

<?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:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
	
	<bean id="singer"  class ="com.cm2easy.miki.example.chapter1.Singer"></bean>

</beans>
 

Singer singer = new Singer();

<?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:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
	
	<bean id="singer"  class ="com.cm2easy.miki.example.chapter1.Singer">
		<constructor-arg value="聽媽媽的話"></constructor-arg>
	</bean>

</beans>

Singer singer = new Singer("聽媽媽的話");

/**
 * 樂器介面
 * @author liuyc
 *
 */
public interface Instrument {
	public void play(String melodyName);
}

/**
 * 鋼琴類
 * @author liuyc
 *
 */
public class Piano implements Instrument{
	@Override
	public void play(String melodyName) {
		System.out.println("正在演奏" + melodyName);
	}
}

<?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:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
	
	<bean id="singer"  class ="com.cm2easy.miki.example.chapter1.Singer">
		<constructor-arg value="聽媽媽的話"></constructor-arg>
		<constructor-arg ref="piano"></constructor-arg>
	</bean>
	<bean id="piano" class="com.cm2easy.miki.example.chapter1.Piano"></bean>
</beans>