[Java] 스프링(Spring) 컨테이너(Container)와 빈(Bean)의 생명 주기(Life Cycle) 및 범위(Scope)

지난 시간에 스프링(Spring)의

DI(Dependency Injection)와

IOC 컨테이너(Container)를 학습했습니다

아직 안보고 오셨다면

아래의 링크 ↓↓

2020/09/23 - [Java] - [Java] 스프링(Spring) DI(Dependency Injection)과 IOC 컨테이너(Container)

[Java] 스프링(Spring) DI(Dependency Injection)과 IOC 컨테이너(Container)

오늘은 스프링의 컨테이너와 빈(Bean) 객체의

생명 주기(Life Cycle)와 범위(Scope)를 보겠습니다

1. applicationCTX.xml

<?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.xsd">

	<bean id="calculator" class="com.example.demo.Calculator" />
	
	<bean id="myCalculator" class="com.example.demo.MyCalculator" scope="singleton">
		<property name="calculator">
			<ref bean="calculator"/>
		</property>
		<property name="firstNum" value="10" />
		<property name="secondNum" value="2"></property>
	</bean>
</beans>

2. Calculator.java

package com.example.demo;

public class Calculator {
	public void addition(int firstNum, int secondNum) {
		System.out.println("addition()");
		int result = firstNum + secondNum;
		System.out.println(firstNum + " + " + secondNum + " = " + result);
	}
	
	public void subtraction(int firstNum, int secondNum) {
		System.out.println("subtraction()");
		int result = firstNum - secondNum;
		System.out.println(firstNum + " - " + secondNum + " = " + result);
	}
	
	public void multiplication(int firstNum, int secondNum) {
		System.out.println("multiplication()");
		int result = firstNum * secondNum;
		System.out.println(firstNum + " * " + secondNum + " = " + result);
	}
	
	public void division(int firstNum, int secondNum) {
		System.out.println("division()");
		if ( secondNum == 0 ) {
			System.out.println("It cannot be divided by zero.");
		}
		int result = firstNum / secondNum;
		System.out.println(firstNum + " / " + secondNum + " = " + result);
	}
}

3. MyCalculator.java

package com.example.demo;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
public class MyCalculator implements InitializingBean, DisposableBean {

	Calculator calculator;
	private int firstNum;
	private int secondNum;
	
	public MyCalculator() {

	}

	public void add() {
		calculator.addition(firstNum, secondNum);
	}
	
	public void sub() {
		calculator.subtraction(firstNum, secondNum);
	}
	
	public void mul() {
		calculator.multiplication(firstNum, secondNum);
	}
	
	public void div() {
		calculator.division(firstNum, secondNum);
	}
	
	public void setCalculator(Calculator calculator) {
		this.calculator = calculator;
	}
	
	public void setFirstNum(int firstNum) {
		this.firstNum = firstNum;
	}
	
	public void setSecondNum(int secondNum) {
		this.secondNum = secondNum;
	}

	@Override
	public void destroy() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("destroy()");
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("afterPropertiesSet()");
	}
}

4. MainClass.java

package com.example.demo;
import org.springframework.context.support.GenericXmlApplicationContext;
public class MainClass {
	public static void main(String[] args) {
		String configLocation = "classpath:applicationCTX.xml";
		GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
		ctx.load(configLocation);
		ctx.refresh();
		MyCalculator myCalculator1 = ctx.getBean("myCalculator", MyCalculator.class);
		
		myCalculator1.add();
		myCalculator1.sub();
		myCalculator1.mul();
		myCalculator1.div();
		
		MyCalculator myCalculator2 = ctx.getBean("myCalculator", MyCalculator.class);
		myCalculator2.add();
		myCalculator2.sub();
		myCalculator2.mul();
		myCalculator2.div();
		
		if ( myCalculator1 == myCalculator2 ) {
			System.out.println("myCalculator1 == myCalculator2");
		} else {
			System.out.println("myCalculator1 != myCalculator2");
		}
		
		ctx.close();
	}
}

위의 코드에서 컨테이너의 생명주기를

살펴보면 아래와 같습니다

빈(Bean)의 경우는

컨테이너가 소멸할 때 자동 소멸하게 되는데요

만약 빈만 소멸하게 하려면

위의 코드에서는 destroy()를 호출하면되겠죠?

또 빈이 초기화 또는 소멸할 때

호출되는 afterPropertiesSet()과 destory()를

InitializingBean, DisposableBean 인터페이스를

구현함으로써 정의할 수 있습니다

이 방법 외에도

@PostConstruct, @PreDestroy

이노테이션을 사용할 수 있는데요

아래의 코드를 참고하세요~

1. applicationCTX.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">

	<context:annotation-config />
	
	<bean id="calculator" class="com.example.demo.Calculator" />
	
	<bean id="myCalculator" class="com.example.demo.MyCalculator" scope="singleton">
		<property name="calculator">
			<ref bean="calculator"/>
		</property>
		<property name="firstNum" value="10" />
		<property name="secondNum" value="2"></property>
	</bean>
</beans>

2. MyCalculator.java

package com.example.demo;
import javax.annotation.*;
public class MyCalculator {

	Calculator calculator;
	private int firstNum;
	private int secondNum;
	
	public MyCalculator() {

	}

	public void add() {
		calculator.addition(firstNum, secondNum);
	}
	
	public void sub() {
		calculator.subtraction(firstNum, secondNum);
	}
	
	public void mul() {
		calculator.multiplication(firstNum, secondNum);
	}
	
	public void div() {
		calculator.division(firstNum, secondNum);
	}
	
	public void setCalculator(Calculator calculator) {
		this.calculator = calculator;
	}
	
	public void setFirstNum(int firstNum) {
		this.firstNum = firstNum;
	}
	
	public void setSecondNum(int secondNum) {
		this.secondNum = secondNum;
	}
	
	@PostConstruct
	public void initMethod() {
		System.out.println("initMethod()");
	}
	
	@PreDestroy
	public void destoryMethod() {
		System.out.println("destoryMethod()");
	}
}

마지막으로 빈의 범위(Scope)는

xml 파일에 scope으로 설정이 가능한데요

위의 코드에서는 singleton으로 설정했습니다

singleton 패턴에 대해 잘 모르신다면

아래의 링크 ↓↓

2020/06/14 - [Java] - [Design Pattern] 싱글톤(Singleton) 패턴과 프로토타입(Prototype) 패턴

[Design Pattern] 싱글톤(Singleton) 패턴과 프로토타입(Prototype) 패턴

이상으로 오늘의 학습을 마치겠습니다

그럼 이만-_-