<div id="readability-page-1" class="page"><div><h2 data-ke-size="size26">Strategy Design&nbsp;Pattern&nbsp;</h2>
<p data-ke-size="size16">대부분의 기능은 동일하지만, 타입에 따라 일부 동작만 다르게 처리해야하는 경우, 유용한 디자인 패턴이다.&nbsp;</p>
<p data-ke-size="size16">본 글에서는 결제 방법 (토스 혹은 포인트 결제)에 따라 장바구니 기능이 다르게 동작하는 예제를 설명할 것이다.&nbsp;</p>
<h2 data-ke-size="size26">Diagram&nbsp;</h2>
<figure data-ke-mobilestyle="widthOrigin" data-filename="스크린샷 2023-02-11 오후 1.52.02.png" data-origin-width="1872" data-origin-height="1116"><span data-url="https://blog.kakaocdn.net/dn/bEzAGv/btrYSOAGiTp/mdDnl55U2ckqlBtXjy6UdK/img.png" data-lightbox="lightbox"><img src="https://blog.kakaocdn.net/dn/bEzAGv/btrYSOAGiTp/mdDnl55U2ckqlBtXjy6UdK/img.png" onerror="this.onerror=null; this.src='//t1.daumcdn.net/tistory_admin/static/images/no-image-v1.png'; this.srcset='//t1.daumcdn.net/tistory_admin/static/images/no-image-v1.png';" data-filename="스크린샷 2023-02-11 오후 1.52.02.png" data-origin-width="1872" data-origin-height="1116"></span></figure>


<h2 data-ke-size="size26">Example</h2>
<pre id="code_1676089560487" data-ke-language="java" data-ke-type="codeblock"><code>public interface PaymentStrategy {

	public void pay(int amount);
}</code></pre>

<pre id="code_1676089645966" data-ke-language="java" data-ke-type="codeblock"><code>public class PointStrategy implements PointStrategy {

	private String userId;
	
	public PointStrategy(String userId){
		this.userId=userId;
	}
	@Override
	public void pay(int amount) {
		System.out.println(amount +" paid with point");
	}

}</code></pre>
<pre id="code_1676089676953" data-ke-language="java" data-ke-type="codeblock"><code>public class TosssStrategy implements PaymentStrategy {

	private String orderId;
	
	public TosssStrategy(String orderId){
		this.orderNo=orderNo;
	}
	
	@Override
	public void pay(int amount) {
		System.out.println(amount + " paid using Toss.");
	}

}</code></pre>
<pre id="code_1676090378836" data-ke-language="java" data-ke-type="codeblock"><code>@Getter
@AllArgsConstructor
public class Item {
	private String id;
	private Money price;
}</code></pre>
<pre id="code_1676090451296" data-ke-language="java" data-ke-type="codeblock"><code>public class ShoppingCart {

	private List&lt;Item&gt; items;
	
	public ShoppingCart(){
		this.items=new ArrayList&lt;Item&gt;();
	}
	
	public void addItem(Item item){
		this.items.add(item);
	}
	
	public void removeItem(Item item){
		this.items.remove(item);
	}
	
	public int calculateTotal(){
		int sum = 0;
		for(Item item : items){
			sum += item.getPrice();
		}
		return sum;
	}
	
	public void pay(PaymentStrategy paymentMethod){
		int amount = calculateTotal();
		paymentMethod.pay(amount);
	}
}</code></pre>
<pre id="code_1676090502402" data-ke-language="java" data-ke-type="codeblock"><code>public class ShoppingCartTest {

	public static void main(String[] args) {
		ShoppingCart cart = new ShoppingCart();
		
		Item item1 = new Item("1234",10);
		Item item2 = new Item("5678",40);
		
		cart.addItem(item1);
		cart.addItem(item2);
		
		// 토스 결제인 경우
		cart.pay(new TossStrategy("1"));
		
		// 포인트 결제인 경우
		cart.pay(new PointStrategy("1"));
	}

}</code></pre>

<h2 data-ke-size="size26">Reference</h2>
<p data-ke-size="size16"><a href="https://www.digitalocean.com/community/tutorials/strategy-design-pattern-in-java-example-tutorial" target="_blank" rel="noopener">https://www.digitalocean.com/community/tutorials/strategy-design-pattern-in-java-example-tutorial</a></p>
<p data-ke-size="size16">머메이드 다이어그램</p>
<pre id="code_1676091111327" data-ke-language="java" data-ke-type="codeblock"><code>---
title: PaymentStrategy
---
classDiagram
    class Item{
        -String id
        -Money price
        +getId()
        +getPrice()
    }
    class ShoppingCart{
        -List&lt;Item&gt; items
        +addItem(Item item)
        +removeItem(Item item)
        +calculateTotal()
        +pay(PaymentStrategy paymentMethod)

    }
    class PaymentStrategy 
    &lt;&lt;interface&gt;&gt; PaymentStrategy
    PaymentStrategy : pay()    
    class TosstStrategy{
        +pay()
    }
    class PointStrategy{
        +pay()
    }
    PaymentStrategy &lt;|-- TosstStrategy : implements
    PaymentStrategy &lt;|-- PointStrategy : implements</code></pre>
</div></div>

복세편살

Strategy Design Pattern 
대부분의 기능은 동일하지만, 타입에 따라 일부 동작만 다르게 처리해야하는 경우, 유용한 디자인 패턴이다. 
본 글에서는 결제 방법 (토스 혹은 포인트 결제)에 따라 장바구니 기능이 다르게 동작하는 예제를 설명할 것이다. 
Diagram 
 
Example
public interface PaymentStrategy {
	public void pay(int amount);
}
 
public class PointStrategy implements PointStrategy {
	private String userId;
	
	public PointStrategy(String userId){
		this.userId=userId;
	}
	@Override
	public void pay(int amount) {
		System.out.println(amount +" paid with point");
	}
}
public class TosssStrategy implements PaymentStrategy {
	private String orderId;
	
	public TosssStrategy(String orderId){
		this.orderNo=orderNo;
	}
	
	@Override
	public void pay(int amount) {
		System.out.println(amount + " paid using Toss.");
	}
}
@Getter
@AllArgsConstructor
public class Item {
	private String id;
	private Money price;
}
public class ShoppingCart {
	private List<Item> items;
	
	public ShoppingCart(){
		this.items=new ArrayList<Item>();
	}
	
	public void addItem(Item item){
		this.items.add(item);
	}
	
	public void removeItem(Item item){
		this.items.remove(item);
	}
	
	public int calculateTotal(){
		int sum = 0;
		for(Item item : items){
			sum += item.getPrice();
		}
		return sum;
	}
	
	public void pay(PaymentStrategy paymentMethod){
		int amount = calculateTotal();
		paymentMethod.pay(amount);
	}
}
public class ShoppingCartTest {
	public static void main(String[] args) {
		ShoppingCart cart = new ShoppingCart();
		
		Item item1 = new Item("1234",10);
		Item item2 = new Item("5678",40);
		
		cart.addItem(item1);
		cart.addItem(item2);
		
		// 토스 결제인 경우
		cart.pay(new TossStrategy("1"));
		
		// 포인트 결제인 경우
		cart.pay(new PointStrategy("1"));
	}
}
 
Reference
https://www.digitalocean.com/community/tutorials/strategy-design-pattern-in-java-example-tutorial
머메이드 다이어그램
---
title: PaymentStrategy
---
classDiagram
    class Item{
        -String id
        -Money price
        +getId()
        +getPrice()
    }
    class ShoppingCart{
        -List<Item> items
        +addItem(Item item)
        +removeItem(Item item)
        +calculateTotal()
        +pay(PaymentStrategy paymentMethod)
    }
    class PaymentStrategy 
    <<interface>> PaymentStrategy
    PaymentStrategy : pay()    
    class TosstStrategy{
        +pay()
    }
    class PointStrategy{
        +pay()
    }
    PaymentStrategy <|-- TosstStrategy : implements
    PaymentStrategy <|-- PointStrategy : implements
 
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디자인패턴 - Strategy Design Pattern

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