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🌈 백엔드/스프링 프레임워크

스프링_애너테이션

소소한 알마 2023. 7. 20. 17:54
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[5] 스프링 DI - 객체 속성 

환경설정 파일을 만든다 

 

(1) proteotype 과 singleton 

prototype : 참조할때마다 새로운 자바빈 객체를 생성하여 주소값이 달라진다

singleton : 참조할때 항상 같은 객체의 주소값을 참조한다 , 생략할수 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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
   	   
       //prototype : 요청할때마다 new bean 객체 생성 
       <bean id ="car" class ="com.fastcapus.ch3.car" scppe="proteotype"/>
      
       // singleton : 컨테이너 당 하나의 객체만 생성 
  	   <bean id ="engine" class ="com.fastcapus.ch3.Engine" scppe="singleton"/>
       
       // singleton은 생략 가능 
  	   <bean id ="door" class ="com.fastcapus.ch3.Door"/>

</beans>
package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;

class Car{}
class Engine{}
class Door{}

public class SpringDiTest {

    public static void main(String[] args) {
    
    	//환경설정파일
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        
        Car car = (Car) ac.getBean("car"); // byName. 
        //Car car = ac.getBean("car", Car.class); 위와 똑같은 다른방법1 (타입도 기재했기때문에 형변환 안해도됨)
        //Car car2 = (Car) ac.getBean(Car.class); 위와 똑같은 다른방법2 (타입)

        Engine engine = (Engine) ac.getBean("engine"); // byName
        Engine engine = (Engine) ac.getBean(Engine.class); // byType - 같은 타입이 3개라서 에러
        Door door = (Door) ac.getBean("door");

   
        System.out.println("car = " + car);
    }
}

 

(2) 객체의 속성을 부여한다 : 직접 부여 

<?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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
   	   
       <bean id ="car" class ="com.fastcapus.ch3.car">
  	   <bean id ="engine" class ="com.fastcapus.ch3.Engine">
  	   <bean id ="door" class ="com.fastcapus.ch3.Door"/>

</beans>
package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;

class Car{

	// 부여할 속성을 정의한다 
 	String color;
    int oil;
    Engine engine;
    Door[] doors;

    public void setColor(String color) {
        this.color = color;
    }

    public void setOil(int oil) {
        this.oil = oil;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public void setDoors(Door[] doors) {
        this.doors = doors;
    }

    @Override
    public String toString() {
        return "Car{" +
                "color='" + color + '\'' +
                ", oil=" + oil +
                ", engine=" + engine +
                ", doors=" + Arrays.toString(doors) +
                '}';
    }
}

public class SpringDiTest {

    public static void main(String[] args) {
    
    	
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        
        Car car = (Car) ac.getBean("car"); // byName. 

        Engine engine = (Engine) ac.getBean("engine"); // byName
        Engine engine = (Engine) ac.getBean(Engine.class); // byType - 같은 타입이 3개라서 에러
        Door door = (Door) ac.getBean("door");

        
        // 속성 값 적용
        car.setColor("red");
        car.setOil(100);
        car.setEngine(engine);
        car.setDoors(new Door[]{ ac.getBean("door", Door.class), (Door)ac.getBean("door")});
        
        System.out.println("car = " + car);
    }
}

 

(3) 객체의 속성을 부여한다 : 파일에 속성 참조 

클래스에 입력하는 대신 파일에 속성을 부여하여 참조시킨다 

<?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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
   	   
       
       <bean id ="car" class ="com.fastcapus.ch3.car">
       		<property name ="color" value="red"/>
      		<property name ="oil" value="100"/>
       		<property name ="engine" ref="engine"/>
      		<property name ="doors">
            	<array value-type="com.fastcapus.ch3.Door">
            		<ref bean="door"/>
                    <ref bean="door"/>
                </array> 
           </property>     
       </bean>
       
  	   <bean id ="engine" class ="com.fastcapus.ch3.Engine">
  	   <bean id ="door" class ="com.fastcapus.ch3.Door"/>

</beans>
package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;


class Car{

	String color;
    int oil;
    Engine engine;
    Door[] doors;
  

    public void setColor(String color) {
        this.color = color;
    }

    public void setOil(int oil) {
        this.oil = oil;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public void setDoors(Door[] doors) {
        this.doors = doors;
    }

    @Override
    public String toString() {
        return "Car{" +
                "color='" + color + '\'' +
                ", oil=" + oil +
                ", engine=" + engine +
                ", doors=" + Arrays.toString(doors) +
                '}';
    }
}

public class SpringDiTest {

    public static void main(String[] args) {
    
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        
        Car car = (Car) ac.getBean("car"); // byName. 

        Engine engine = (Engine) ac.getBean("engine"); // byName
        Engine engine = (Engine) ac.getBean(Engine.class); // byType - 같은 타입이 3개라서 에러
        Door door = (Door) ac.getBean("door");
        
        System.out.println("car = " + car);
    }
}

 

(4) 객체의 속성을 부여한다 : 생성자에 속성 참조 

파일에 생성자로 속성을 부여하여 참조시킨다

위에 property 대신에 constructor-arg 생성자를 통해 설정할수도 있다 . 대신 클래스에 생성자를 만들어야한다

<?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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 
       <bean id ="car" class ="com.fastcapus.ch3.car">
       		
            <constructor-arg name ="color" value="red"/>
      		<constructor-arg name ="oil" value="100"/>
       		<constructor-arg name ="engine" ref="engine"/>
      		<constructor-arg name ="doors">
            	<array value-type="com.fastcapus.ch3.Door">
            		<ref bean="door"/>
                    <ref bean="door"/>
                </array> 
           </constructor-arg>     
       </bean>
       
  	   <bean id ="engine" class ="com.fastcapus.ch3.Engine"/>
  	   <bean id ="door" class ="com.fastcapus.ch3.Door"/>

</beans>
package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;


class Car{
   
    public Car() {} 
    public Car(String color, int oil, Engine engine, Door[] doors) {
        this.color = color;
        this.oil = oil;
        this.engine = engine;
        this.doors = doors;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public void setOil(int oil) {
        this.oil = oil;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public void setDoors(Door[] doors) {
        this.doors = doors;
    }

    @Override
    public String toString() {
        return "Car{" +
                "color='" + color + '\'' +
                ", oil=" + oil +
                ", engine=" + engine +
                ", doors=" + Arrays.toString(doors) +
                '}';
    }
}

public class SpringDiTest {

    public static void main(String[] args) {
    
    	
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        
        Car car = (Car) ac.getBean("car"); // byName. 
       
        Engine engine = (Engine) ac.getBean("engine"); // byName
        Engine engine = (Engine) ac.getBean(Engine.class); // byType - 같은 타입이 3개라서 에러
        Door door = (Door) ac.getBean("door");
      
        System.out.println("car = " + car);
    }
}

(5) 객체의 속성을 부여한다 : component-scan , Autowired , Value 

<?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.xsd">
    <context:component-scan base-package="com.fastcampus.ch3">
       
       //ch3에 있는 같은 이름의 car가 있어서 충돌났음 . 제외하라는 명령어 
       <context:exclude-filter type="regex" expression="com.fastcampus.ch3.diCopy*.*"/>
    
    </context:component-scan>
    <context:annotation-config/>
</beans>
package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;

@Component("engine") class Engine{}    
// <bean id="engine" class="com.fastcampus.ch3.Engine"/> 와 같다

@Component class SuperEngine extends Engine {}
@Component class TurboEngine extends Engine{}
@Component class Door{}

@Component
class Car{
    @Value("red") String color;
    @Value("100") int oil;
    
    @Autowired  Engine engine;   
    // byType - 타입으로 먼저 검색, 여러개면 이름으로 검색. -  superEngine, turboEngine
    
    @Autowired Door[] doors;

    public Car() {} // 기본 생성자를 꼭 만들어주자
    public Car(String color, int oil, Engine engine, Door[] doors) {
        this.color = color;
        this.oil = oil;
        this.engine = engine;
        this.doors = doors;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public void setOil(int oil) {
        this.oil = oil;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public void setDoors(Door[] doors) {
        this.doors = doors;
    }

    @Override
    public String toString() {
        return "Car{" +
                "color='" + color + '\'' +
                ", oil=" + oil +
                ", engine=" + engine +
                ", doors=" + Arrays.toString(doors) +
                '}';
    }
}

public class SpringDiTest {
    public static void main(String[] args) {
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        Car car = (Car) ac.getBean("car"); // byName. 아래와 같은 문장
        Car car = ac.getBean("car", Car.class); // byName
        Car car2 = (Car) ac.getBean(Car.class); // byType

        Engine engine = (Engine) ac.getBean("engine"); // byName
        //Engine engine = (Engine) ac.getBean(Engine.class); 
        // byType - Engine.class 으로 같은 타입이 3개라서 에러가뜸 (engine, superEngine,turboEngine)
        Door door = (Door) ac.getBean("door");

        car.setColor("red");
        car.setOil(100);
        car.setEngine(engine);
        car.setDoors(new Door[]{ ac.getBean("door", Door.class), (Door)ac.getBean("door")});
        System.out.println("car = " + car);
    }
}

 

만약에 engine이 Component가 되지 않는다면 

@Autowired할때 engine은 검색되지 않고 , superEngine 과 turboEngine 만 검색되므로 Engine의 키 값인 engine을 찾을수 없어 오류가 뜬다. 이경우 어떤 타입이 우선인지 @Qualifier를 입력한다 

 

package com.fastcampus.ch3;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;

class Engine{}    

@Component class SuperEngine extends Engine {}
@Component class TurboEngine extends Engine{}
@Component class Door{}

@Component
class Car{
    @Value("red") String color;
    @Value("100") int oil;
    
    @Autowired
    @Qualifier("superEngine") Engine engine;   
    /*위와 같은 type으로 찾는 방식 대신 아래의 name으로 찾는 방식도 사용가능하다 
    @Resouce(name="superEngine") Engine engine;
    */ 
    
    
    @Autowired Door[] doors;

    public Car() {} 
    public Car(String color, int oil, Engine engine, Door[] doors) {
        this.color = color;
        this.oil = oil;
        this.engine = engine;
        this.doors = doors;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public void setOil(int oil) {
        this.oil = oil;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public void setDoors(Door[] doors) {
        this.doors = doors;
    }

    @Override
    public String toString() {
        return "Car{" +
                "color='" + color + '\'' +
                ", oil=" + oil +
                ", engine=" + engine +
                ", doors=" + Arrays.toString(doors) +
                '}';
    }
}

public class SpringDiTest {
    public static void main(String[] args) {
        ApplicationContext ac = new GenericXmlApplicationContext("config.xml");
        Car car = (Car) ac.getBean("car"); // byName. 아래와 같은 문장
        Car car = ac.getBean("car", Car.class); // byName
        Car car2 = (Car) ac.getBean(Car.class); // byType

        Engine engine = (Engine) ac.getBean("engine"); // byName
        //Engine engine = (Engine) ac.getBean(Engine.class); 
        // byType - Engine.class 으로 같은 타입이 3개라서 에러가뜸 (engine, superEngine,turboEngine)
        Door door = (Door) ac.getBean("door");

        car.setColor("red");
        car.setOil(100);
        car.setEngine(engine);
        car.setDoors(new Door[]{ ac.getBean("door", Door.class), (Door)ac.getBean("door")});
        System.out.println("car = " + car);
    }
}

 

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