[Spring] 002 강의노트

배윤석·2022년 7월 1일
SpringTIL
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Spring

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Spring

Spring Framework

DI

  • Dependency Injection : 의존성 주입
    Spring DI 의존성 주입 참고자료
    • 객체 자체가 아니라, Framework에 의해 객체의 의존성이 주입되는 설계 패턴
    • Framework에 의해 동적으로 주입되므로, 여러 객체 간의 결합이 줄어듬
    • DI는 Spring Framework에서 지원하는 IoC의 형태.
    • 클래스 간의 의존 관계를 빈 설정 정보를 바탕으로 컨테이너가 자동으로 연결해줌
    • DI는 Spring Framework에서 지원하는 IoC의 형태

의존성 주입을 사용한다면 무엇이 좋은가?

의존성 주입을 이용한다면 의존하는(필요한) 클래스를 직접 생성하는것이 아닌, 주입해 줌으로써, 객체간의 결합도를 줄이고, 좀더 유연한 코드를 생성할 수 있게 된다.

즉, 한 클래스를 수정하였을 때, 다른 클래스도 수정해야 하는 상황을 막아줄 수 있다.

IoC

  • IOC란 "제어의 역전"이라는 의미로, 말 그대로 메소드가 객체의 호출 작업을 개발자가 하는것이 아니라, 외부에서 결정되는 것을 의미한다.
  • 프로그램 제어권을 Frameowrk가 가져가는 것
  • 생성된 객체의 생명주기 '전체'에 대한 권한과 관리를 프레임 워크에 주어, 개발자는 비지니스 로직에만 신경쓰면 된다.
  • 개발자가 설정만 하면 (annotaion , xml 등을 통해 설정해놓으면) Container가 알아서 처리한다.

이것을 잘 보면 Database의 Pooling 개념하고 비슷한거 같다.
스프링 ➡ 객체를 만들어놓고 가져다 쓴다.
데이터베이스 ➡ 연결을 만들어놓고 가져다 사용한다.

  • DI 에서 배워야 할 것은?
    생성자를 생성하면? ➡ 초기화
    디폴트 / 오버로딩 생성자
    Setter / Getter 메서드를 통해 초기화
    ➡ 생성시키고 초기화 시키는 방법론을 배운다.

다형성을 생각할때는 라이브러리를 만드는 것이 아니라 호출해서 사용하는 것이 편하다.
MVC Model 2를 하게되면 다른 곳에서 호출해서 사용할 수 있다.

어제 작성했던 인터페이스 구현받았던 코드를 Spring 을 사용해 작성해보자.

Hello.java , HelloBean1.java , HelloBean2.java 는 동일하다.
context.xml은 패키지명을 수정해주자.

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring04.HelloBean1"></bean>
	<bean name="helloBean2" class="com.exam.spring04.HelloBean2"></bean>
</beans>

App.java

package com.exam.spring04;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
        // 1
		GenericXmlApplicationContext ctx =
		new GenericXmlApplicationContext("classpath:com/exam/spring04/context.xml");
		
        // 2
		Hello hello = (Hello)ctx.getBean("helloBean1");
		
        // 3
        hello.sayHello("홍길동");
		
		hello = (Hello)ctx.getBean("helloBean2");
		hello.sayHello("박문수");
		
        // 4
		ctx.close();
	}
}

1 : 객체를 미리 선언

  • Spring을 통해 객체를 미리 선언하는 역할을 한다.
  • 가져올 객체는 context.xml 파일에 경로를 입력한다.
  • GenericXmlApplicationContext 클래스를 통해 인스턴스화 해서 ctx 변수에 저장한다.
  • 이때 ctx에 저장될 내용은 context.xml 파일 내용이다.

2 : Spring에 선언된 객체를 가져오기

  • ctx의 Bean을 가져온다.
  • ctx 변수에 저장된 helloBean1 이라는 이름의 com.exam.spring04.HelloBean1 클래스를 가져와 Hello 클래스를 인스턴스화 해서 hello 변수에 저장한다.

3 hello에 저장된 메서드 호출

  • hello에 저장된 ctx에서 Bean

4 : 작업 완료시 Spring 닫아주기

  • 모든 수행 작업이 완료되면 GenericXmlApplicationContext 을 .close() 메서드를 사용해 닫아준다.

실행 결과

19 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring04/context.xml]
09:50:46.021 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
09:50:46.048 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean1'
09:50:46.062 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean2'
홍길동님 안녕하세요?
Hello 박문수
09:50:46.090 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 09:50:46 KST 2022

멤버변수

  1. 인스턴스 멤버변수
    • 사용시에 new
  2. 클래스 멤버변수
    • static 미리 new

scope

singleton : 클래스
prototype : 인스턴스

Maven 프로젝트 생성하고

  1. pom.xml dependency에 Spring 라이브러리 추가
  2. JDK 버전 맞추기(ver.11)
  3. 우클릭 - Maven Update 해주기

Singleton

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring01.HelloBean" scope="singleton"></bean>
	<bean name="helloBean2" class="com.exam.spring01.HelloBean" scope="singleton"></bean>
</beans>
package com.exam.spring01;

public class HelloBean {
	
	public HelloBean() {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean() 생성자 호출");
	}
	
	public void sayHello(String name) {
		System.out.println(name + "님 안녕하세요");
	}
}

package com.exam.spring01;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {
    public static void main( String[] args ) {
        GenericXmlApplicationContext ctx
        = new GenericXmlApplicationContext("classpath:com/exam/spring01/context.xml");
        
        ctx.close();
    }
}
10:27:35.724 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring01/context.xml]
10:27:35.726 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
10:27:35.758 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean1'
HelloBean() 생성자 호출
10:27:35.773 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean2'
HelloBean() 생성자 호출
10:27:35.810 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:27:35 KST 2022

singleton scope를 빼고 bean을 입력해본다면?

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring01.HelloBean" scope="singleton"></bean>
	<bean name="helloBean2" class="com.exam.spring01.HelloBean" scope="singleton"></bean>
	<bean name="helloBean2" class="com.exam.spring01.HelloBean"></bean>
</beans>
10:30:52.156 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from class path resource [com/exam/spring01/context.xml]
10:30:52.158 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
10:30:52.181 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean1'
HelloBean() 생성자 호출
10:30:52.196 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean2'
HelloBean() 생성자 호출
10:30:52.196 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean3'
HelloBean() 생성자 호출
10:30:52.226 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:30:52 KST 2022

생성자가 호출된다.
이를 통해 알 수 있는 점은?
Bean의 생성시점? 로딩은 안해도 생성이 된다.
scope의 디폴트 값은 singleton이다.

package com.exam.spring01;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {
    public static void main( String[] args ) {
        GenericXmlApplicationContext ctx
        = new GenericXmlApplicationContext("classpath:com/exam/spring01/context.xml");
        
        // helloBean
        HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        HelloBean helloBean12 = (HelloBean)ctx.getBean("helloBean2");
        
        HelloBean helloBean13 = (HelloBean)ctx.getBean("helloBean1");
        
        helloBean11.sayHello("홍길동");
        helloBean12.sayHello("박문수");
        
        System.out.println(helloBean11);
        System.out.println(helloBean12);
        System.out.println(helloBean13);
        
        ctx.close();
    }
}
10:33:50.367 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from class path resource [com/exam/spring01/context.xml]
10:33:50.370 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
10:33:50.403 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean1'
HelloBean() 생성자 호출
10:33:50.416 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean2'
HelloBean() 생성자 호출
10:33:50.417 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'helloBean3'
HelloBean() 생성자 호출
홍길동님 안녕하세요
박문수님 안녕하세요
com.exam.spring01.HelloBean@505fc5a4
com.exam.spring01.HelloBean@5fbdfdcf
com.exam.spring01.HelloBean@505fc5a4
10:33:50.445 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:33:50 KST 2022

scope

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring02.HelloBean" scope="prototype"></bean>
	<bean name="helloBean2" class="com.exam.spring02.HelloBean" scope="prototype"></bean>
</beans>
package com.exam.spring02;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring02/context.xml");
		
		ctx.close();
	}

}
10:36:55.059 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring02/context.xml]
10:36:55.061 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
10:36:55.124 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:36:55 KST 2022
package com.exam.spring02;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring02/context.xml");
		
		HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        HelloBean helloBean12 = (HelloBean)ctx.getBean("helloBean2");
        
        HelloBean helloBean13 = (HelloBean)ctx.getBean("helloBean1");
        
        helloBean11.sayHello("홍길동");
        helloBean12.sayHello("박문수");
        
        System.out.println(helloBean11);
        System.out.println(helloBean12);
        System.out.println(helloBean13);
		
		ctx.close();
	}

}
10:38:17.910 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring02/context.xml]
10:38:17.913 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
HelloBean() 생성자 호출
HelloBean() 생성자 호출
HelloBean() 생성자 호출
홍길동님 안녕하세요
박문수님 안녕하세요
com.exam.spring02.HelloBean@76c3e77a
com.exam.spring02.HelloBean@78123e82
com.exam.spring02.HelloBean@67c33749
10:38:17.994 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:38:17 KST 2022

정리

Scope가 싱글톤이다?
최초 프로그램 시작 시점에 객체를 생성한다.

Scope가 프로토타입이다?
객체 필요시에만(생성자 선언 했을 경우) 객체를 생성한다.

디폴트 생성자가 아닐 경우에는 어떻게 초기화를 시켜줄수 있을 것이냐?

생성자의 주입

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring03.HelloBean" scope="prototype"></bean>
</beans>
package com.exam.spring03;

public class HelloBean {
	private String name;
	
	public HelloBean() {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean() 생성자 호출");
		this.name = "홍길동";
	}
	
	public HelloBean(String name) {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean(String name) 생성자 호출");
		this.name = name;
	}
	
	public void sayHello() {
		System.out.println(this.name + "님 안녕하세요");
	}
}
package com.exam.spring03;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring03/context.xml");
		
		HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        helloBean11.sayHello();
		
		ctx.close();
	}
}
10:48:32.947 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring03/context.xml]
10:48:32.949 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
HelloBean() 생성자 호출
홍길동님 안녕하세요
10:48:33.015 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:48:32 KST 2022

위에꺼는 디폴트 생성자였고 이번엔 생성자의 오버라이딩?

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring03.HelloBean" scope="prototype"></bean>
	
	<bean name="helloBean2" class="com.exam.spring03.HelloBean" scope="prototype">
		<constructor-arg>
			<value>박문수</value>
		</constructor-arg>
	</bean>
</beans>

Hello.java는 동일해서 패스

package com.exam.spring03;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring03/context.xml");
		
		HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        helloBean11.sayHello();
        
        HelloBean helloBean12 = (HelloBean)ctx.getBean("helloBean2");
        helloBean12.sayHello();
		
		ctx.close();
	}
}
10:53:35.105 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring03/context.xml]
10:53:35.107 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
HelloBean() 생성자 호출
홍길동님 안녕하세요
HelloBean(String name) 생성자 호출
박문수님 안녕하세요
10:53:35.201 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:53:35 KST 2022

생성자 주입시 xml 을 줄여 사용할 수 있다.

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring03.HelloBean" scope="prototype"></bean>
	
	<bean name="helloBean2" class="com.exam.spring03.HelloBean" scope="prototype">
		<constructor-arg>
			<value>박문수</value>
		</constructor-arg>
	</bean>
	
	<bean name="helloBean3" class="com.exam.spring03.HelloBean" scope="prototype">
		<constructor-arg value="이몽룡" />
	</bean>
</beans>
package com.exam.spring03;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring03/context.xml");
		
		HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        helloBean11.sayHello();
        
        HelloBean helloBean12 = (HelloBean)ctx.getBean("helloBean2");
        helloBean12.sayHello();
        
        HelloBean helloBean13 = (HelloBean)ctx.getBean("helloBean3");
        helloBean13.sayHello();
		
		ctx.close();
	}
}
10:55:55.975 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from class path resource [com/exam/spring03/context.xml]
10:55:55.977 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
HelloBean() 생성자 호출
홍길동님 안녕하세요
HelloBean(String name) 생성자 호출
박문수님 안녕하세요
HelloBean(String name) 생성자 호출
이몽룡님 안녕하세요
10:55:56.063 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 10:55:55 KST 2022
<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean name="helloBean1" class="com.exam.spring04.HelloBean" scope="prototype"></bean>
	
	<bean name="helloBean2" class="com.exam.spring04.HelloBean" scope="prototype">
		<constructor-arg>
			<value>박문수</value>
		</constructor-arg>
	</bean>
	
	<bean name="helloBean3" class="com.exam.spring04.HelloBean" scope="prototype">
		<constructor-arg value="이몽룡" />
	</bean>
	
	<bean name="helloBean4" class="com.exam.spring04.HelloBean" scope="prototype">
		<constructor-arg>
			<value>문수</value>
		</constructor-arg>
		<constructor-arg>
			<value>박</value>
		</constructor-arg>
	</bean>
</beans>
package com.exam.spring04;

public class HelloBean {
	private String name;
	
	public HelloBean() {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean() 생성자 호출");
		this.name = "홍길동";
	}
	
	public HelloBean(String name) {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean(String name) 생성자 호출");
		this.name = name;
	}
	
	public HelloBean(String firstName, String secondName) {
		// TODO Auto-generated constructor stub
		System.out.println("HelloBean(String firstName, String secondName) 생성자 호출");
		this.name = secondName + " " + firstName;
	}
	
	public void sayHello() {
		System.out.println(this.name + "님 안녕하세요");
	}
}
package com.exam.spring04;

import org.springframework.context.support.GenericXmlApplicationContext;


public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring04/context.xml");
		
		HelloBean helloBean11 = (HelloBean)ctx.getBean("helloBean1");
        helloBean11.sayHello();
        
        HelloBean helloBean12 = (HelloBean)ctx.getBean("helloBean2");
        helloBean12.sayHello();
        
        HelloBean helloBean13 = (HelloBean)ctx.getBean("helloBean3");
        helloBean13.sayHello();
        
        HelloBean helloBean14 = (HelloBean)ctx.getBean("helloBean4");
        helloBean14.sayHello();
		
		ctx.close();
	}
}
11:14:47.285 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 4 bean definitions from class path resource [com/exam/spring04/context.xml]
11:14:47.287 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
HelloBean() 생성자 호출
홍길동님 안녕하세요
HelloBean(String name) 생성자 호출
박문수님 안녕하세요
HelloBean(String name) 생성자 호출
이몽룡님 안녕하세요
HelloBean(String firstName, String secondName) 생성자 호출
박 문수님 안녕하세요
11:14:47.374 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 11:14:47 KST 2022

게시판
앞에서 해온것은 단순히 문자열만 받았지만
이번에 해볼것은? 사용자적인 객체를 받는다.

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<!-- WriteAction action = new WriteAction(new BoardTO) 와 동일한 개념이다. -->
	<bean name="action2" class="com.exam.spring05.WriteAction" scope="prototype" >
		<constructor-arg>
			<bean class="com.exam.spring05.BoardTO" />
		</constructor-arg>
	</bean>
</beans>
package com.exam.spring05;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring05/context.xml");
		
		WriteAction action = (WriteAction)ctx.getBean("action1");
		action.excute();
		
		ctx.close();
	}
}

먼저 인스턴스화 해서 가져오고 싶어!

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<!-- 먼저 인스턴스화해서 가져오고 싶어 -->
	<bean id="to" class="com.exam.spring05.BoardTO" />
	<!-- WriteAction action = new WriteAction(to) 와 동일한 개념이다. -->
	<bean name="action3" class="com.exam.spring05.WriteAction" scope="prototype" >
		<constructor-arg>
			<ref bean="to" />
		</constructor-arg>
	</bean>
	
</beans>
package com.exam.spring05;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App03 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring05/context.xml");
		
		WriteAction action = (WriteAction)ctx.getBean("action3");
		action.excute();
		
		ctx.close();
	}
}

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean id="to" class="com.exam.spring07.model1.BoardTO" >
		<constructor-arg value="홍길동" />
	</bean>
	
	<bean id="dao" class="com.exam.spring07.model1.BoardDAO" >
		<constructor-arg ref="to" />
	</bean>
	
	<bean id="action" class="com.exam.spring07.model2.WriteAction" >
		<constructor-arg ref="dao" />
	</bean>
	
</beans>

xml 에서는 실행될 준비를 한다.
아래 Java 프로그램을 보면, 호출될 객체는 action 이다.
action을 실행하기 위해 필요한 인자값들은 context.xml에서 조립한다.

  1. action의 인자값으로 BoardDAO 가 필요하기 때문에, dao를 만들었다.
  2. dao의 인자값으로 BoardTO가 필요하기 때문에, to를 만들었다.
  3. to의 인자값으로는 홍길동을 넣어주었다.
package com.exam.spring07.model1;

public class BoardTO {
	private String writer;
	
	public BoardTO(String writer) {
		// TODO Auto-generated constructor stub
		System.out.println("BoardTO(String writer) 호출");
		this.writer = writer;
	}
}
package com.exam.spring07.model1;

public class BoardDAO {
	private BoardTO to;
	
	public BoardDAO(BoardTO to) {
		// TODO Auto-generated constructor stub
		System.out.println("BoardDAO(BoardTO to) 호출");
		this.to = to;
	}
}
package com.exam.spring07.model2;

import com.exam.spring07.model1.BoardDAO;

public class WriteAction {
	private BoardDAO dao;
	
	public WriteAction(BoardDAO dao) {
		// TODO Auto-generated constructor stub
		System.out.println("WriteAction(BoardDAO dao) 호출");
		this.dao = dao;
	}
	
	public void execute() {
		System.out.println("execute() : " + dao);
	}
}
package com.exam.spring07;

import org.springframework.context.support.GenericXmlApplicationContext;

import com.exam.spring07.model2.WriteAction;

public class App02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring07/context.xml");
		
		WriteAction action = (WriteAction)ctx.getBean("action");
		action.execute();
		
		ctx.close();
	}
}

context.xml 에서는 조립을 해주고
App02.java 에서는 호출만 해준다.

실행 결과는 다음과 같다.

xml의 순서대로
BoardTO를 선언해준다.
인자값으로 문자열 형식의 writer를 받는다.
➡ writer = 홍길동

그 다음 BoardDAO를 선언해준다.
인자값으로 BoardTO 형식의 to를 받는다.
➡ to = 홍길동 인자값이 들어간 BoardTO

마지막으로 WriteAction을 선언해준다.
인자값으로 BoardDAO 형식의 dao를 받는다.
➡ dao = 홍길동 인자값이 들어간 BoardTO를 내부적으로 가공(처리)한 데이터

App02.java에서는 xml에서 조립해준 정보들을 action이라는 변수에 저장했다가, 실행시킨다.

14:08:47.417 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from class path resource [com/exam/spring07/context.xml]
14:08:47.419 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
14:08:47.447 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'to'
BoardTO(String writer) 호출
14:08:47.478 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'dao'
BoardDAO(BoardTO to) 호출
14:08:47.479 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'action'
WriteAction(BoardDAO dao) 호출
execute() : com.exam.spring07.model1.BoardDAO@66f57048
14:08:47.506 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 14:08:47 KST 2022

Setter와 Getter로 의존성 주입하기

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean id="to" class="com.exam.spring04.BoardTO" scope="prototype" >
		<property name="seq" value="1" />
		<property name="subject" value="제목" />
	</bean>
	<bean id="action" class="com.exam.spring04.WriteAction" scope="prototype" >
		<property name="to" ref="to" />
	</bean>
</beans>
package com.exam.spring04;

public class BoardTO {
	private int seq;
	private String subject;
	
	public int getSeq() {
		return seq;
	}
	public void setSeq(int seq) {
		System.out.println("setSeq(int seq)");
		this.seq = seq;
	}
	public String getSubject() {
		return subject;
	}
	public void setSubject(String subject) {
		System.out.println("setSubject(String subject)");
		this.subject = subject;
	}
}
package com.exam.spring04;

public class WriteAction {
	private BoardTO to;
	
	public BoardTO getTo() {
		return to;
	}
	
	public void setTo(BoardTO to) {
		this.to = to;
	}
	
	public void execute() {
		System.out.println("execute() 호출");
		System.out.println(to.getSeq());
		System.out.println(to.getSubject());
	}
}
package com.exam.spring04;

import org.springframework.context.support.GenericXmlApplicationContext;

import com.exam.spring02.BoardTO;

public class App02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring04/context.xml");
		
		WriteAction action = (WriteAction)ctx.getBean("action");
		action.execute();
		
		ctx.close();
	}
}

실행 결과

14:47:25.595 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 2 bean definitions from class path resource [com/exam/spring04/context.xml]
14:47:25.597 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
setSeq(int seq)
setSubject(String subject)
execute() 호출
1
제목
14:47:25.705 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 14:47:25 KST 2022

collection 계열

list
hash set
hash map

list

map

<?xml version="1.0" encoding= "UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
	
	<bean id="listTO" class="com.exam.spring06.BoardListTO" scope="prototype">
		<property name="userMaps">
			<map>
				<entry key="key1">
					<value>데이터 1</value>
				</entry>
				
				<entry key="key2">
					<value>데이터 2</value>
				</entry>
			</map>
		</property>
		<property name="boardMaps">
			<map>
				<entry key="key1">
					<bean id="boardTO" class="com.exam.spring06.BoardTO" scope="prototype">
						<property name="seq" value="1" />
						<property name="subject" value="제목1" />
					</bean>
				</entry>
				<entry key="key2">
					<bean id="boardTO" class="com.exam.spring06.BoardTO" scope="prototype">
						<property name="seq" value="2" />
						<property name="subject" value="제목2" />
					</bean>
				</entry>
			</map>
		</property>
	</bean>
</beans>
package com.exam.spring06;

public class BoardTO {
	private int seq;
	private String subject;
	
	public int getSeq() {
		return seq;
	}
	public void setSeq(int seq) {
		System.out.println("setSeq(int seq)");
		this.seq = seq;
	}
	public String getSubject() {
		return subject;
	}
	public void setSubject(String subject) {
		System.out.println("setSubject(String subject)");
		this.subject = subject;
	}
}
package com.exam.spring06;

import java.util.HashMap;

public class BoardListTO {
	private HashMap<String, String> userMaps;
	private HashMap<String, BoardTO> boardMaps;

	public HashMap<String, String> getUserMaps() {
		return userMaps;
	}

	public void setUserMaps(HashMap<String, String> userMaps) {
		this.userMaps = userMaps;
	}

	public HashMap<String, BoardTO> getBoardMaps() {
		return boardMaps;
	}

	public void setBoardMaps(HashMap<String, BoardTO> boardMaps) {
		this.boardMaps = boardMaps;
	}
}
package com.exam.spring06;

import org.springframework.context.support.GenericXmlApplicationContext;

public class App02 {
	public static void main(String[] args) {
		GenericXmlApplicationContext ctx
		= new GenericXmlApplicationContext("classpath:com/exam/spring06/context.xml");
		
		BoardListTO listTO = (BoardListTO)ctx.getBean("listTO");
		
		// value 값 가져오기
		for(String value : listTO.getUserMaps().values()) {
			System.out.println(value);
		}
		
		// key 값 가져오기
		for(String key : listTO.getUserMaps().keySet()) {
			System.out.println(key);
		}
		
		// BoardTO 값 가져오기
		for(BoardTO to : listTO.getBoardMaps().values()) {
			System.out.print(to.getSeq()+" ");
			System.out.println(to.getSubject());
		}
		ctx.close();
	}
}
16:26:48.214 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 1 bean definitions from class path resource [com/exam/spring06/context.xml]
16:26:48.216 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Refreshing org.springframework.context.support.GenericXmlApplicationContext@27fe3806
setSeq(int seq)
setSubject(String subject)
setSeq(int seq)
setSubject(String subject)
데이터 1
데이터 2
key1
key2
1 제목1
2 제목2
16:26:48.338 [main] DEBUG o.s.c.s.GenericXmlApplicationContext - Closing org.springframework.context.support.GenericXmlApplicationContext@27fe3806, started on Fri Jul 01 16:26:48 KST 2022

AOP

  • Aspect Oriented Programming : 관점 중심 프로그래밍

    객체 활용(생성, 소멸 관리)
    서블릿에서의 Filter 기능과 동일하다
    Filter : 전처리 / 후처리

Spring MVC(java ➡ JSP)

Q : 똑같으면 원래 기존꺼도 사용해도 좋잖아요?
분업화의 의미에서 서로 다르게 작업하려고 그렇게 썻다.

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