230622_ Bean과 ApplicationContext

1. 오늘의 일정

1. Spring 숙련

   
   

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2. 배운 내용

1. ApplicationContext와 다양한 Bean 설정 방법

@Configuration
@ComponentScan
public class AppConfig {
    @Bean
    Car car() {
        return new Car();
    }

    @Bean
    @Scope("prototype") // default - @Scope("singleton")
    Engine engine() {
        return new Engine();
    }

    @Bean
    Door door() {
        return new Door();
    }
}

@Component
class Car {
    Engine engine;
    Door door;

    @Override
    public String toString() {
        return "Car{" +
                "engine=" + engine +
                ", door=" + door +
                '}';
    }
}

@Component
class Engine {
}

@Component
class Door {
}

public class Main {
    public static void main(String[] args) {
        // AC 생성 - AC의 설정파일은 AppConfig.class 자바설정
        ApplicationContext ac = new AnnotationConfigApplicationContext(AppConfig.class);
//        Car car = (Car)ac.getBean("car"); // byName
        Car car = ac.getBean("car", Car.class); // 형변환 대신 경로 지정, 위와 동일 코드

        // Bean @Scope("prototype") 붙어있어 여러개 생성 가능
        Engine engine = ac.getBean(Engine.class); // byType, 형변환 불필요
        Engine engine2 = ac.getBean(Engine.class); // byType, 형변환 불필요
        Engine engine3 = ac.getBean(Engine.class); // byType, 형변환 불필요
        System.out.println("car = " + car);
        System.out.println("engine = " + engine);
        System.out.println("engine2 = " + engine2);
        System.out.println("engine3 = " + engine3);

        System.out.println("ac.getBeanDefinitionCount() = " + ac.getBeanDefinitionCount());
        System.out.println("ac.getBeanDefinitionNames() = " + Arrays.toString(ac.getBeanDefinitionNames()));
//        System.out.println("ac.containsBeanDefinition(\"engine\") = " + ac.containsBeanDefinition("engine"));
//        System.out.println("ac.isSingleton(\"car\") = " + ac.isSingleton("car"));
//        System.out.println("ac.isPrototype(\"engine\") = " + ac.isPrototype("engine"));
    }
}