Spring 自动化装配Bean
声明一张cd的接口:
public interface CompactDisc { public abstract void play();}
实现cd接口:
@Component("SgtPeppers")public class SgtPeppers implements CompactDisc { private String title = "Sgt.Pepper's Lonely Hearts Club Band"; private String artist = "The Beatles"; @Override public void play() { System.out.println("playing" + title + " by " + artist); }}
声明cdplayer:
@Component("CDplayer")//表明该类作为组件类,没必要显示的配置Bean实例,括号内为组件名public class CDPlayer { /* * @Autowired注解可以用在构造器上,也可以用在set方法上,也能直接放在下列代码所示地方 * spring会满足有该注解的依赖,如果只有一个bean匹配依赖需求的话,这个bean就会被装配进来 @Autowired 默认按类型装配 * */ @Autowired private CompactDisc cd; public CompactDisc getCd() { return cd; } public void setCd(CompactDisc cd) { this.cd = cd; } public void play(){ cd.play(); }}
测试类:
public class CDPlayerTest { public static void main(String[] args) { ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml"); CDPlayer cdPlayer= (CDPlayer) context.getBean("CDplayer"); cdPlayer.play(); }}
xml:自动扫描包,寻找有注解的类
<context:component-scan base-package="com.xue.soundsystem"></context:component-scan>
总结:@Component:相当于xml的bean中添加其实例,括号内为id。@Autowired会按类型寻找匹配的实例进行匹配。@Resource可以按照名字进行装配。
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