案例一
- 定义接口 CD.java
package interfacepackage;public interface CD { void play();} - 定义接口 player .java
package interfacepackage;//定义一个播放器接口public interface player { void play();} - 定义接口的实现类 CD1.java
package bean;import org.springframework.stereotype.Component;import annotation_self.CD1_Annotation;import annotation_self.CD_Annotation;import interfacepackage.CD;@Component@CD_Annotation //使用自定义限定符来标识这个bean，类似于bean的id@CD1_Annotation //使用自定义限定符来标识这个bean，类似于bean的idpublic class CD1 implements CD{ @Override public void play() { System.out.println("我是 CD1"); } } - 定义接口的实现类 CD2.java
package bean;import org.springframework.stereotype.Component;import annotation_self.CD2_Annotation;import annotation_self.CD_Annotation;import interfacepackage.CD;@Component@CD_Annotation //使用自定义限定符来标识这个bean，类似于bean的id属性@CD2_Annotation //使用自定义限定符来标识这个bean，类似于bean的id属性public class CD2 implements CD{ @Override public void play() { System.out.println("我是 CD2"); } } - 定义接口的实现类 CDPlayer.java
package bean;import interfacepackage.CD;import interfacepackage.player;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component;import annotation_self.CD2_Annotation;import annotation_self.CD_Annotation;@Component("cdp")public class CDPlayer implements player { @Autowired @CD_Annotation @CD2_Annotation //表示注入的bean的限定符必须有@CD_Annotation和@CD2_Annotation private CD cd; @Override public void play() { cd.play(); }} - 定义配置类 CDPlayerConfig.java
package config;import interfacepackage.CD;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import bean.CDPlayer;@Configuration@ComponentScan(basePackages="bean")public class CDPlayerConfig {} - 自定义注解限定符 CD_Annotation .java
package annotation_self;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import org.springframework.beans.factory.annotation.Qualifier;@Target({ElementType.CONSTRUCTOR,ElementType.FIELD,ElementType.METHOD,ElementType.TYPE}) //该自定义注解限定符的作用目标@Retention(RetentionPolicy.RUNTIME)@Qualifier //说明这是个自定义限定符public @interface CD_Annotation {} - 自定义注解限定符 CD1_Annotation .java
package annotation_self;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import org.springframework.beans.factory.annotation.Qualifier;@Target({ElementType.CONSTRUCTOR,ElementType.FIELD,ElementType.METHOD,ElementType.TYPE}) //该自定义注解限定符的作用目标@Retention(RetentionPolicy.RUNTIME)@Qualifier //说明这是个自定义限定符public @interface CD1_Annotation {} - 自定义注解限定符 CD2_Annotation .java
package annotation_self;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import org.springframework.beans.factory.annotation.Qualifier;@Target({ElementType.CONSTRUCTOR,ElementType.FIELD,ElementType.METHOD,ElementType.TYPE}) //该自定义注解限定符的作用目标@Retention(RetentionPolicy.RUNTIME)@Qualifier //说明这是个自定义限定符public @interface CD2_Annotation {} - 编写测试类 Test.java
package test;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;import config.CDPlayerConfig;import bean.CDPlayer;public class Test { public static void main(String[] args) { ApplicationContext context=new AnnotationConfigApplicationContext(CDPlayerConfig.class); CDPlayer cdplayer=(CDPlayer)context.getBean("cdp"); cdplayer.play(); }} 结果：
