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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