DI - 2

스프링 프로퍼티 설정

 

- 자바쪽의 ArrayList 대신에 프로퍼티에서 <list>를 사용해도 됨

 

스프링 컨테이너

 

예제

예제 1

 

<java>

 

//BMICalculator - 비만도를 측정
package com.javalec.spring_4_1;
 
public class BMICalculator {
    private double lowWeight;
    private double normal;
    private double overWeight;
    private double obesity;
    
    public void bmiCalculation(double weight, double height) {
        double h = height * 0.01;
        double result = weight / (h*h);
        
        System.out.println("BMI 지수 : "+(int)result);
        
        if (result > obesity) {
            System.out.println("비만입니다.");
        }else if (result > overWeight) {
            System.out.println("과체중입니다.");            
        }else if (result > normal) {
            System.out.println("정상입니다.");            
        }else {
            System.out.println("저체중입니다.");            
        }
    }
    
    public double getLowWeight() {
        return lowWeight;
    }
    public void setLowWeight(double lowWeight) {
        this.lowWeight = lowWeight;
    }
    public double getNormal() {
        return normal;
    }
    public void setNormal(double normal) {
        this.normal = normal;
    }
    public double getOverWeight() {
        return overWeight;
    }
    public void setOverWeight(double overWeight) {
        this.overWeight = overWeight;
    }
    public double getObesity() {
        return obesity;
    }
    public void setObesity(double obesity) {
        this.obesity = obesity;
    }
}
 
//MyInfo - 나의 정보
package com.javalec.spring_4_1;
 
import java.util.ArrayList;
 
public class MyInfo {
    private String name;
    private double height;
    private double weight;    
    private ArrayList<String> hobbys;
    private BMICalculator bmiCalculator;
    
    public void bmiCalculation() {
        bmiCalculator.bmiCalculation(weight, height);
    }
    
    public void getInfo() {
        System.out.println("이름: "+name);
        System.out.println("키: "+height);
        System.out.println("몸무게: "+weight);
        System.out.println("취미: "+hobbys);
        
        bmiCalculation();
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public double getHeight() {
        return height;
    }
    public void setHeight(double height) {
        this.height = height;
    }
    public double getWeight() {
        return weight;
    }
    public void setWeight(double weight) {
        this.weight = weight;
    }
    public ArrayList<String> getHobbys() {
        return hobbys;
    }
    public void setHobbys(ArrayList<String> hobbys) {
        this.hobbys = hobbys;
    }
    public BMICalculator getBmiCalculator() {
        return bmiCalculator;
    }
    public void setBmiCalculator(BMICalculator bmiCalculator) {
        this.bmiCalculator = bmiCalculator;
    }
}
 
 

 

<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 class="com.javalec.spring_4_1.BMICalculator" id="bmiCalculator">
        <property name="lowWeight" value="18.5"></property>
        <property name="normal" value="23"></property>
        <property name="overWeight">
            <value>25</value>
        </property>
        <property name="obesity">
            <value>30</value>
        </property>
    </bean>
    <bean class="com.javalec.spring_4_1.MyInfo" id="myInfo">
        <property name="name">
            <value>홍길동</value>
        </property>
        <property name="height">
            <value>187</value>
        </property>
        <property name="weight">
            <value>84</value>
        </property>
        <property name="hobbys">
            <list>
                <value>수영</value>
                <value>요리</value>
                <value>독서</value>
            </list>
        </property>
        <property name="bmiCalculator">
            <ref bean="bmiCalculator"/>
        </property>
    </bean>
</beans>
 

 

- bmiCalculator에 위의 모든 값들이 세팅됨

 

<MainClass.java>

 

package com.javalec.spring_4_1;
 
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
 
public class MainClass {
    public static void main(String[] args) {
        String configLoc = "classpath:myInfoCTX.xml";
        AbstractApplicationContext ctx =  new GenericXmlApplicationContext(configLoc);
        MyInfo myInfo = ctx.getBean("myInfo",MyInfo.class);
        myInfo.getInfo();
        ctx.close();        
    }
}

 

 

- MyInfo 클래스에 있는 getInfo() 메서드에 모든 정보가 담겼기 때문에 getInfo() 메서드를 호출

 

DI 활용 - 의존관계

 

생성자를 사용해서 student1 세팅

setter를 통해서 student2 세팅

 

예제

 

<java>

 

//Student 
package com.javalec.spring_5_1;
 
public class Student {
    private String name;
    private String age;
    private String gradeNum;
    private String classNum;
    
    //필드 값을 사용해서 생성자 만든다
    public Student(String name, String age, String gradeNum, String classNum) {
        this.name = name;
        this.age = age;
        this.gradeNum = gradeNum;
        this.classNum = classNum;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String getGradeNum() {
        return gradeNum;
    }
    public void setGradeNum(String gradeNum) {
        this.gradeNum = gradeNum;
    }
    public String getClassNum() {
        return classNum;
    }
    public void setClassNum(String classNum) {
        this.classNum = classNum;
    }
}
 
//StudentInfo 
package com.javalec.spring_5_1;
 
public class StudentInfo {
    private Student student;
    
    //생성자
    public StudentInfo(Student student) {
        this.student = student;
    }
    
    //Studnet클래스 타입의 객체를 통해서 학생 정보 출력
    public void getStudentInfo() {
        System.out.println("이름 : "+student.getName());
        System.out.println("나이 : "+student.getAge());
        System.out.println("학년 : "+student.getGradeNum());
        System.out.println("반 : "+student.getClassNum());
        System.out.println("=========================");
    }
 
    public void setStudent(Student student) {
        this.student = student;
    }
}
 
//MainClass
package com.javalec.spring_5_1;
 
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
 
public class MainClass {
    public static void main(String[] args) {
        String configLoc = "classpath:applicationCTX.xml";
        AbstractApplicationContext ctx = new GenericXmlApplicationContext(configLoc);
        StudentInfo studentInfo = ctx.getBean("studentInfo",StudentInfo.class);
        //StudentInfo메서드가 홍길동 정보를 가지고 있기 때문에 홍길동 출력(student1)
        studentInfo.getStudentInfo();
        
        Student student2 = ctx.getBean("student2",Student.class);
        //student2 정보를 세팅
        studentInfo.setStudent(student2);
        studentInfo.getStudentInfo();
        ctx.close();
    }
}

 

<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 class="com.javalec.spring_5_1.Student" id="student1">
    <!-- 생성자를 사용하여 필드에 값 세팅 -->
    <!-- 값 넣는 방식의 아래의 두 방식 중 어떤 방식 사용해도 상관 없음 -->
        <constructor-arg>
            <value>홍길동</value>
        </constructor-arg>
        <constructor-arg>
            <value>10살</value>
        </constructor-arg>
        <constructor-arg>
            <value>3학년</value>
        </constructor-arg>
        <constructor-arg>
            <value>2반</value>
        </constructor-arg>
    </bean>
    
    <bean class="com.javalec.spring_5_1.Student" id="student2">
        <constructor-arg value="홍길순"></constructor-arg>
        <constructor-arg value="9살"></constructor-arg>
        <constructor-arg value="2학년"></constructor-arg>
        <constructor-arg value="1반"></constructor-arg>
    </bean>
    
    <bean class="com.javalec.spring_5_1.StudentInfo" id="studentInfo">
        <constructor-arg>
            <ref bean="student1"/>
        </constructor-arg>
    </bean>
</beans>

 

 

DI 사용에 따른 장점

 

하나의 id에 여러 클래스를 세팅할 수 있음

 

예제

<인터페이스>

 

package com.javalec.spring_5_2;
 
public interface Pencil {
    //3가지 종류의 연필을 이 인터페이스로부터 
    //상속받아 메서드 오버라이딩
    public void use();
}

 

<클래스>

 

//Pencil4B 
package com.javalec.spring_5_2;
 
public class Pencil4B implements Pencil{
    @Override
    public void use() {
        System.out.println("4B 입니다.");
    }
}
 
//Pencil6B 
package com.javalec.spring_5_2;
 
public class Pencil6B implements Pencil{
 
    @Override
    public void use() {
        System.out.println("6B 입니다.");
    }
    
}
 
//Pencil6BWithEraser 
package com.javalec.spring_5_2;
 
public class Pencil6BWithEraser implements Pencil{
 
    @Override
    public void use() {
        System.out.println("6B이고, 지우개가 있습니다.");
    }
    
}
 
//MainClass 
package com.javalec.spring_5_2;
 
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
 
public class MainClass {
    public static void main(String[] args) {        
        AbstractApplicationContext ctx = new GenericXmlApplicationContext("classpath:applicationCTX.xml");
        //인터페이스 이름으로 클래스를 받아줌
        //참조변수의 이름만 바꾸면 여러 클래스를 사용 가능
        Pencil pencil = ctx.getBean("pencil",Pencil.class);
        pencil.use();
        
        Pencil pencil2 = ctx.getBean("pencil2",Pencil.class);
        pencil2.use();
        
        Pencil pencil3 = ctx.getBean("pencil3",Pencil.class);
        pencil3.use();
    }
}

 

<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 class="com.javalec.spring_5_2.Pencil6BWithEraser" id="pencil"></bean>
    <bean class="com.javalec.spring_5_2.Pencil6B" id="pencil2"></bean>
    <bean class="com.javalec.spring_5_2.Pencil4B" id="pencil3"></bean>
 
</beans>

 

문제 1 - 반지름과 원의 넓이

 

<클래스>

 

//Circle 
package com.javalec.spring_ex5_1;
 
public class Circle {
    private int radius;
    
    public void process(int radius) {
        System.out.println("원의 면적은: "+radius*radius*3.14);
    }
    
    public int getRadius() {
        return radius;
    }
 
    public void setRadius(int radius) {
        this.radius = radius;
    }
 
    public Circle(int radius) {
        this.radius = radius;
    }
}
 
//CircleInfo 
package com.javalec.spring_ex5_1;
 
public class CircleInfo {
    private Circle circle;
 
    public void setCircle(Circle circle) {
        this.circle = circle;
    }
 
    public CircleInfo(Circle circle) {
        this.circle = circle;
    }
    
    public void getCircleInfo() {
        if (circle!=null) {
            int radius = circle.getRadius();
            System.out.println("반지름: "+radius);
            circle.process(radius);
        }
    }
}
 
//MainCircle 
package com.javalec.spring_ex5_1;
 
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
 
public class MainCircle {
    public static void main(String[] args) {
        String configLoc = "classpath:circleCTX.xml";
        AbstractApplicationContext ctx = new GenericXmlApplicationContext(configLoc);
        CircleInfo circleInfo = ctx.getBean("circleInfo",CircleInfo.class);
        circleInfo.getCircleInfo();
        
        Circle circle2 = ctx.getBean("circle2",Circle.class);
        circleInfo.setCircle(circle2);
        circleInfo.getCircleInfo();
    }
}

 

<circleCTX.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 class="com.javalec.spring_ex5_1.Circle" id="circle1">
        <constructor-arg>
            <value>10</value>
        </constructor-arg>
    </bean>
    <bean class="com.javalec.spring_ex5_1.Circle" id="circle2">
        <constructor-arg>
            <value>5</value>
        </constructor-arg>
    </bean>
    <bean class="com.javalec.spring_ex5_1.CircleInfo" id="circleInfo">
        <constructor-arg>
            <ref bean="circle1"/>
        </constructor-arg>
    </bean>
</beans>