打折

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 price * 95 / 100;
+    }
+}

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

@@ -7,22 +7,7 @@ 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 static int calculatePrice(DiscountStrategy strategy, int price, User user) {
+        return strategy.discount(price,user);
     }
 }