Factory Method Pattern

Factory Method Pattern에 대해 설명하는 페이지입니다.

Posted Oct 11, 2023

By HyunJinNo

Tags

Design Pattern, Java

1. Introduction

• Purpose
  • Exposes a method for creating objects, allowing subclasses to control the actual creation process.
• Use When
  • A class will not know what classes it will be required to create.
  • Subclasses may specify what objects should be created.
  • Parent classes wish to defer creation to their subclasses.
• Characteristics
  • Uses inheritance to decide the object to be instantiated.
  • Defines an interface for creating an object, but lets subclasses decide which class to instantiate.
  • Lets a class defer instantiation to subclasses.

2. How to Use (Example)

• Product

  java

  1public abstract class MyProduct {
  2    String name;
  3
  4    public String getName() {
  5        return name;
  6    }
  7}

• Concrete Products

  java

  1public class ProductA extends MyProduct {
  2    public ProductA() {
  3        name = "ProductA";
  4    }
  5}
  6
  7public class ProductB extends MyProduct {
  8    public ProductB() {
  9        name = "ProductB";
  10    }
  11}
  12
  13public class ProductC extends MyProduct {
  14    public ProductC() {
  15        name = "ProductC";
  16    }
  17}
  18
  19public class ProductD extends MyProduct {
  20    public ProductD() {
  21        name = "ProductD";
  22    }
  23}

• Creator

  java

  1public abstract class MyCreator {
  2    public MyProduct orderProduct(String type) {
  3        Product product = createProduct(type);
  4        return product;
  5    }
  6
  7    protected abstract MyProduct createProduct(String type);
  8}

• Concrete Creators

  java

  1public class CreatorAB extends MyCreator {
  2    public MyProduct createProduct(String type) {
  3        Product product;
  4        if (type.equals("A")) {
  5            product = new ProductA();
  6        } else if (type.equals("B")) {
  7            product = new ProductB();
  8        }
  9        return product;
  10    }
  11}
  12
  13public class CreatorCD extends MyCreator {
  14    public MyProduct createProduct(String type) {
  15        Product product;
  16        if (type.equals("C")) {
  17            product = new ProductC();
  18        } else if (type.equals("D")) {
  19            product = new ProductD();
  20        }
  21        return product;
  22    }
  23}