使用策略模式对打折系统进行重构

src/main/java/com/github/hcsp/polymorphism/Discount95Strategy.java

@@ -1,3 +1,8 @@
 package com.github.hcsp.polymorphism;
 
-public class Discount95Strategy {}
+public class Discount95Strategy extends DiscountStrategy{
+    @Override
+    public int discount(int price, User user) {
+        return (int)(price*0.95);
+    }
+}

src/main/java/com/github/hcsp/polymorphism/NoDiscountStrategy.java

@@ -1,3 +1,8 @@
 package com.github.hcsp.polymorphism;
 
-public class NoDiscountStrategy {}
+public class NoDiscountStrategy extends DiscountStrategy{
+    @Override
+    public int discount(int price, User user) {
+        return price;
+    }
+}

src/main/java/com/github/hcsp/polymorphism/OnlyVipDiscountStrategy.java

@@ -1,3 +1,12 @@
 package com.github.hcsp.polymorphism;
 
-public class OnlyVipDiscountStrategy {}
+public class OnlyVipDiscountStrategy extends DiscountStrategy {
+    @Override
+    public int discount(int price, User user) {
+        if (user.isVip()) {
+            return (int) (price * 0.95);
+        } else {
+            return price;
+        }
+    }
+}

src/main/java/com/github/hcsp/polymorphism/PriceCalculator.java

@@ -7,22 +7,24 @@ public class PriceCalculator {
     // OnlyVipDiscountStrategy 只有VIP打95折，其他人保持原价
     // 重构后的方法签名：
     // public static int calculatePrice(DiscountStrategy strategy, int price, User user)
-    public static int calculatePrice(String discountStrategy, int price, User user) {
-        switch (discountStrategy) {
-            case "NoDiscount":
-                return price;
-            case "Discount95":
-                return (int) (price * 0.95);
-            case "OnlyVip":
-                {
-                    if (user.isVip()) {
-                        return (int) (price * 0.95);
-                    } else {
-                        return price;
-                    }
-                }
-            default:
-                throw new IllegalStateException("Should not be here!");
-        }
+    public int calculatePrice(DiscountStrategy discountStrategy, int price, User user) {
+        return discountStrategy.discount(price,user);
+
+//        switch (discountStrategy) {
+//            case "NoDiscount":
+//                return price;
+//            case "Discount95":
+//                return (int) (price * 0.95);
+//            case "OnlyVip":
+//                {
+//                    if (user.isVip()) {
+//                        return (int) (price * 0.95);
+//                    } else {
+//                        return price;
+//                    }
+//                }
+//            default:
+//                throw new IllegalStateException("Should not be here!");
+//        }
     }
 }