JSON 형태로 직렬화를 하게 되면 generic 관련 데이터나 다른 primitive type 데이터를 잃게 될 때의 대처방식

GsonTest6_Generics_TypeToken.java

package com.sds.gson;

import java.lang.reflect.Type;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class GsonTest6_Generics_TypeToken {

	public GsonTest6_Generics_TypeToken() {
		Shape<Circle> shape = new Shape<Circle>();
		Circle circle = new Circle(5.0);
		shape.setShape(circle);
		
		// Type 을 정의한다
		Type shapeType = new TypeToken<Shape<Circle>>() {}.getType();
		
		Gson gson = new Gson();
		String json = gson.toJson(shape, shapeType);
		System.out.println("json = "+json);
		
		Shape shape1 = gson.fromJson(json, Shape.class);
		System.out.println(shape1.getShape().getClass());
		System.out.println(shape1.getShape().toString());
		System.out.println(shape1.getArea());
		
		Shape shape2 = gson.fromJson(json,  shapeType);
		System.out.println(shape2.getShape().getClass());
		System.out.println(shape2.getShape().toString());
		System.out.println(shape2.getArea());
	}

	public static void main(String[] args) {
		new GsonTest6_Generics_TypeToken();
	}

}

class Shape<T> {
	public T shape;

	public void setShape(T shape) {
		this.shape = shape;
	}

	public T getShape() {
		return shape;
	}

	public double getArea() {
		if (shape instanceof Circle) {
			return ((Circle) shape).getArea();
		} else {
			return 0.0;
		}
	}
}

class Circle {
	private double radius;
	
	public Circle(double radius) {
		this.radius = radius;
	}

	public String toString() {
		return "Circle";
	}

	public double getRadius() {
		return radius;
	}

	public void setRadius(double radius) {
		this.radius = radius;
	}

	public double getArea() {
		return (radius * radius * 3.14);
	}
}