Spring / Java를 통한 DI 설정방법

[Java를 통한 DI 설정방법]

: 어노테이션 이용하기

Student.java

public class Student {
    
    private String name;
    private int age;
    private ArrayList<String> hobbies;
    private double height;
    private double weight; // 필드 
    
    public Student(String name, int age, ArrayList<String> hobbies) {
        this.name = name;
        this.age = age;
        this.hobbies = hobbies; // name, age, hobbies만 생성자 선언
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
 
    public ArrayList<String> getHobbies() {
        return hobbies;
    }
 
    public void setHobbies(ArrayList<String> hobbies) {
        this.hobbies = hobbies;
    }
 
    public double getHeight() {
        return height;
    }
 
    public void setHeight(double height) {
        this.height = height;
    }
 
    public double getWeight() {
        return weight;
    }
 
    public void setWeight(double weight) { // 전체 setter, getter
        this.weight = weight;
    } 
}

*

5개의 필드 + 3개의 생성자 + 전체 setter, getter

ApplicationConfig.java

@Configuration
public class ApplicationConfig {
    
    @Bean
    public Student student1() {
        ArrayList<String> hobbies = new ArrayList<String>();
        hobbies.add("수영");
        hobbies.add("요리");
 
        Student student = new Student("yul", 100, hobbies);
        student.setHeight(170);
        student.setWeight(60);
        return student;
    }
    
    @Bean
    public Student student2() {
        ArrayList<String> hobbies = new ArrayList<String>();
        hobbies.add("음악");
        hobbies.add("독서");
 
        Student student = new Student("hong", 30, hobbies);
        student.setHeight(170);
        student.setWeight(60);
        return student;
        
    }
 
}

*

생소하고 낯설 뿐이지 어려운 것은 아니다.

그동안 xml파일에서 Bean으로 만들어주었던 부분을 java 애너테이션화 했을 뿐

@Configuration :

이 어노테이션은 설정파일로 쓸거라고 선언하는 것과 같다.

@Bean

xml에서 하나의 객체를 나타낸 것처럼 Bean 어노테이션을 쓰고

자바에서 인스턴스 객체 생성, 접근을 한 것처럼 똑같이 해주기만 하면 된다.

MainClass.java

public class MainClass {
 
    public static void main(String[] args) {
 
        AnnotationConfigApplicationContext ctx 
                    = new AnnotationConfigApplicationContext(ApplicationConfig.class);
        
        Student student1 = ctx.getBean("student1", Student.class);
        System.out.println("이름 : " + student1.getName());
        System.out.println("나이 : " + student1.getAge());
        System.out.println("취미 : " + student1.getHobbies());
        System.out.println("신장 : " + student1.getHeight());
        System.out.println("체중 : " + student1.getWeight());
        System.out.println("============================");
        
        Student student2 = ctx.getBean("student2", Student.class);
        System.out.println("이름 : " + student2.getName());
        System.out.println("나이 : " + student2.getAge());
        System.out.println("취미 : " + student2.getHobbies());
        System.out.println("신장 : " + student2.getHeight());
        System.out.println("체중 : " + student2.getWeight());
        
        ctx.close();
    }
 
}