feat : SOLID - OCP 샘플 코드 구현

놀이터(예제 코드 작성)/solid-design-pattern-sample/README.md

@@ -17,6 +17,17 @@
 - 계좌에 입금할 수 있다.
 - 계좌에서 출금할 수 있다.
 
+### OCP(Open/Closed Principle)
+
+- 개방-폐쇄 원칙
+- 소프트웨어 요소는 확장에는 열려 있으나 변경에는 닫혀 있어야 한다.
+
+#### 구현 요구사항
+
+- 최초의 결제방식은 현금, 카드 두 가지가 있다.
+- 쿠폰 결제방식을 추가한다고 가정한다.
+- 쿠폰으로 결제할 경우 잔고가 차감되지 않는다.
+
 ## 참고자료
 
 - [SOLID (객체 지향 설계)](https://ko.wikipedia.org/wiki/SOLID_(%EA%B0%9D%EC%B2%B4_%EC%A7%80%ED%96%A5_%EC%84%A4%EA%B3%84)) 

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/CardPaymentService.kt

@@ -0,0 +1,20 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentRepository
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+import org.springframework.stereotype.Repository
+
+@Repository
+class CardPaymentService(
+    private val paymentRepository: PaymentRepository
+): PaymentServiceAfter {
+    override fun pay(request: PaymentRequestAfter): Payment {
+        println("카드 결제로 ${request.amount}원을 차감합니다.")
+        return paymentRepository.createPayment(request.amount, request.paymentType)
+    }
+
+    override fun getPaymentType(): PaymentType {
+        return PaymentType.CARD
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/CashPaymentService.kt

@@ -0,0 +1,20 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentRepository
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+import org.springframework.stereotype.Repository
+
+@Repository
+class CashPaymentService(
+    private val paymentRepository: PaymentRepository
+): PaymentServiceAfter {
+    override fun pay(request: PaymentRequestAfter): Payment {
+        println("현금드 결제로 ${request.amount}원을 차감합니다.")
+        return paymentRepository.createPayment(request.amount, request.paymentType)
+    }
+
+    override fun getPaymentType(): PaymentType {
+        return PaymentType.CASH
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/CouponPaymentService.kt

@@ -0,0 +1,20 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentRepository
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+import org.springframework.stereotype.Repository
+
+@Repository
+class CouponPaymentService(
+    private val paymentRepository: PaymentRepository
+): PaymentServiceAfter {
+    override fun pay(request: PaymentRequestAfter): Payment {
+        println("쿠폰 결제는 잔고 차감이 없습니다.")
+        return paymentRepository.createPayment(request.amount, request.paymentType)
+    }
+
+    override fun getPaymentType(): PaymentType {
+        return PaymentType.COUPON
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/PaymentController.kt

@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/payments")
+@RestController
+class PaymentController(
+    private val paymentServiceFactory: PaymentServiceFactory
+) {
+    @PostMapping("with-ocp")
+    fun pay(request: PaymentRequestAfter): Payment {
+        val paymentService = paymentServiceFactory.getPaymentService(request.paymentType)
+        return paymentService.pay(request)
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/PaymentRequestAfter.kt

@@ -0,0 +1,8 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+
+data class PaymentRequestAfter(
+    val amount: Int,
+    val paymentType: PaymentType
+)

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/PaymentServiceAfter.kt

@@ -0,0 +1,10 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+
+interface PaymentServiceAfter {
+    fun pay(request: PaymentRequestAfter): Payment
+
+    fun getPaymentType(): PaymentType
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/after/PaymentServiceFactory.kt

@@ -0,0 +1,27 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+import org.springframework.stereotype.Component
+
+@Component
+class PaymentServiceFactory(val paymentServices: List<PaymentServiceAfter>) {
+    fun getPaymentService(paymentType: PaymentType): PaymentServiceAfter {
+        return this.paymentServices.find { it.getPaymentType() == paymentType }
+            ?: throw NoSuchElementException("해당 결제방식에 대한 구현이 존재하지 않습니다.")
+    }
+}
+
+//@Component
+//class PaymentServiceFactory(
+//    private val cashPaymentService: CashPaymentService,
+//    private val cardPaymentService: CardPaymentService,
+//    private val couponPaymentService: CouponPaymentService
+//) {
+//    fun findPaymentService(paymentType: PaymentType): PaymentServiceAfter {
+//        return when (paymentType) {
+//            PaymentType.CASH -> cashPaymentService
+//            PaymentType.CARD -> cardPaymentService
+//            PaymentType.COUPON -> couponPaymentService
+//        }
+//    }
+//}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/before/PaymentControllerBefore.kt

@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.before
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/payments")
+@RestController
+class PaymentControllerBefore(
+    private val paymentServiceBefore: PaymentServiceBefore
+) {
+    @PostMapping("/none-ocp")
+    fun pay(@RequestBody request: PaymentRequestBefore): Payment {
+        return paymentServiceBefore.pay(request)
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/before/PaymentRequestBefore.kt

@@ -0,0 +1,8 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.before
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+
+data class PaymentRequestBefore(
+    val amount: Int,
+    val type: PaymentType
+)

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/before/PaymentServiceBefore.kt

@@ -0,0 +1,21 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.before
+
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.Payment
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentRepository
+import com.banjjoknim.soliddesignpatternsample.solid.ocp.common.PaymentType
+import org.springframework.stereotype.Service
+
+@Service
+class PaymentServiceBefore(
+    private val paymentRepository: PaymentRepository
+) {
+    fun pay(request: PaymentRequestBefore): Payment {
+        when (request.type) {
+            PaymentType.CASH -> println("현금 결제로 ${request.amount}원을 차감합니다.")
+            PaymentType.CARD -> println("카드 결제로 ${request.amount}원을 차감합니다.")
+            PaymentType.COUPON -> println("쿠폰 결제는 잔고 차감이 없습니다.")
+            // NewPaymentType -> ...
+        }
+        return paymentRepository.createPayment(request.amount, request.type)
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/common/Payment.kt

@@ -0,0 +1,12 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.common
+
+import javax.persistence.Entity
+import javax.persistence.Id
+
+@Entity
+class Payment(
+    val amount: Int,
+    val type: PaymentType,
+    @Id
+    val id: Long = 0L
+)

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/common/PaymentRepository.kt

@@ -0,0 +1,5 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.common
+
+interface PaymentRepository {
+    fun createPayment(amount: Int, paymentType: PaymentType): Payment
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/common/PaymentRepositoryStub.kt

@@ -0,0 +1,10 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.common
+
+import org.springframework.stereotype.Repository
+
+@Repository
+class PaymentRepositoryStub : PaymentRepository {
+    override fun createPayment(amount: Int, paymentType: PaymentType): Payment {
+        return Payment(amount = amount, type = paymentType)
+    }
+}

놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/ocp/common/PaymentType.kt

@@ -0,0 +1,7 @@
+package com.banjjoknim.soliddesignpatternsample.solid.ocp.common
+
+enum class PaymentType {
+    CASH,
+    CARD,
+    COUPON
+}