DI 불편함을 느끼는 코드

spring/di/Program.java

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+package spring.di;
+
+import spring.di.entity.Exam;
+import spring.di.entity.NewlecExam;
+import spring.di.ui.ExamConsole;
+import spring.di.ui.GridExamConsole;
+import spring.di.ui.InlineExamConsole;
+
+public class Program {
+
+	public static void main(String[] args) {
+
+		Exam exam = new NewlecExam();
+		ExamConsole console = new InlineExamConsole(exam); // DI
+		//ExamConsole console = new GridExamConsole(exam);
+
+		/*
+			new InlineExamConsole(exam)
+			new FridExamConsole(exam)
+			
+			같은 메서드를 호출하게되는 위 코드의 수정을 대신해줄 수 있도록 하는 기능이 Spring의 DI다.
+
+		 */
+		console.print();
+
+	}
+
+}

spring/di/entity/Exam.java

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+package spring.di.entity;
+
+public interface Exam {
+	int total();
+	float avg();
+}

spring/di/entity/NewlecExam.java

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+package spring.di.entity;
+
+public class NewlecExam implements Exam {
+
+	private int kor;
+	private int eng;
+	private int math;
+	private int com;
+	
+	@Override
+	public int total() {
+		// TODO Auto-generated method stub
+		return kor+eng+math+com;
+	}
+
+	@Override
+	public float avg() {
+		// TODO Auto-generated method stub
+		return total() / 4.0f;
+	}
+
+}

spring/di/ui/ExamConsole.java

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+package spring.di.ui;
+
+public interface ExamConsole {
+	void print();
+}

spring/di/ui/GridExamConsole.java

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+package spring.di.ui;
+
+import spring.di.entity.Exam;
+
+public class GridExamConsole implements ExamConsole {
+
+	private Exam exam;		
+	
+	public GridExamConsole(Exam exam) {		
+		this.exam = exam;
+	}
+	@Override
+	public void print() {
+		System.out.println("┌──────────┬──────────┐");
+		System.out.println("│   total  │    avg   │");
+		System.out.println("├──────────┼──────────┤");
+		 System.out.printf("│   %3d  │    %3.2f   │\n", exam.total(), exam.avg());
+		System.out.println("└──────────┴──────────┘");
+	}
+
+}

spring/di/ui/InlineExamConsole.java

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+package spring.di.ui;
+
+import spring.di.entity.Exam;
+
+public class InlineExamConsole implements ExamConsole {
+
+	private Exam exam;		
+	
+	public InlineExamConsole(Exam exam) {		
+		this.exam = exam;
+	}
+
+	@Override
+	public void print() {
+		System.out.printf("total is %d, avg is %f\n", exam.total(), exam.avg());
+	}
+
+}