package ch2.annotation;//target/elementType用来设定注解的使用范围
import java.lang.annotation.ElementType;
import java.lang.annotation.Target;//表明这个注解documented会被javac工具记录
import java.lang.annotation.Documented;//retention/retentionPolicy(保留)注解,在编译的时候会被保留在某个(那个)特定的编译阶段
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;//target/elementType用来设定注解的使用范围:type用于类或接口上
@Target(ElementType.TYPE)//retention/retentionPolicy(保留)注解,在编译的时候会被保留在某个(那个)特定的编译阶段
//这种类型的Annotations将被JVM保留
@Retention(RetentionPolicy.RUNTIME)//表明这个注解@documented会被javac工具记录
@Documented//组合注解
//组合configuration元注解
@Configuration
//组合ComponentScan元注解
@ComponentScan//组合注解
public @interface WiselyConfiguration {//覆盖value参数
String[] value() default{};}
package ch2.annotation;import org.springframework.stereotype.Service;//声明为spring的组件
@Service//演示服务Bean
public class DemoService {public void outputResult()
{
System.out.println("从组合注解配置里,照样获得Bean");
}}
package ch2.annotation;//引入ch2.annotation下的包
//使用wiselyConfiguration组合注解代替@ComponentScan,@Configuration
@WiselyConfiguration("ch2.annotation")//新的配置类
public class DemoConfig {}
package ch2.annotation;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class Main {public static void main(String[] args)
{AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(DemoConfig.class);
DemoService demoService = context.getBean(DemoService.class);
demoService.outputResult();
context.close();}}