【设计模式】用Java实现策略模式

// 定义排序策略接口
interface SortingStrategy {
    void sort(int[] array);
}
// 实现具体的排序策略类
class BubbleSortStrategy implements SortingStrategy {
    public void sort(int[] array) {
        System.out.println("Sorting array using Bubble Sort.");
        // 实现具体的冒泡排序算法
    }
}
class QuickSortStrategy implements SortingStrategy {
    public void sort(int[] array) {
        System.out.println("Sorting array using Quick Sort.");
        // 实现具体的快速排序算法
    }
}
// 定义客户端类，使用策略进行排序
class SortClient {
    private SortingStrategy sortingStrategy;
    public void setSortingStrategy(SortingStrategy sortingStrategy) {
        this.sortingStrategy = sortingStrategy;
    }
    public void performSort(int[] array) {
        sortingStrategy.sort(array);
    }
}
// 使用示例
public class Main {
    public static void main(String[] args) {
        SortClient client = new SortClient();
        // 使用冒泡排序策略
        SortingStrategy bubbleSortStrategy = new BubbleSortStrategy();
        client.setSortingStrategy(bubbleSortStrategy);
        int[] array = {5, 2, 8, 1, 9};
        client.performSort(array);
        // 使用快速排序策略
        SortingStrategy quickSortStrategy = new QuickSortStrategy();
        client.setSortingStrategy(quickSortStrategy);
        int[] anotherArray = {10, 7, 3, 6, 4};
        client.performSort(anotherArray);
    }
}

// 定义策略接口
interface DiscountStrategy {
    double applyDiscount(double amount);
}
// 实现具体的策略类
class ChristmasDiscountStrategy implements DiscountStrategy {
    public double applyDiscount(double amount) {
        System.out.println("Applying Christmas discount.");
        return amount * 0.8; // 打八折
    }
}
class BlackFridayDiscountStrategy implements DiscountStrategy {
    public double applyDiscount(double amount) {
        System.out.println("Applying Black Friday discount.");
        return amount * 0.7; // 打七折
    }
}
// 定义客户端类，使用策略进行折扣计算
class ShoppingCart {
    private DiscountStrategy discountStrategy;
    public void setDiscountStrategy(DiscountStrategy discountStrategy) {
        this.discountStrategy = discountStrategy;
    }
    public double calculateTotalAmount(double amount) {
        double discountedAmount = discountStrategy.applyDiscount(amount);
        // 其他计算逻辑...
        return discountedAmount;
    }
}
// 使用示例
public class Main {
    public static void main(String[] args) {
        ShoppingCart cart = new ShoppingCart();
        // 使用圣诞折扣策略
        DiscountStrategy christmasDiscount = new ChristmasDiscountStrategy();
        cart.setDiscountStrategy(christmasDiscount);
        double amount = 100.0;
        double totalAmount = cart.calculateTotalAmount(amount);
        System.out.println("Total amount after discount: " + totalAmount);
        // 使用黑色星期五折扣策略
        DiscountStrategy blackFridayDiscount = new BlackFridayDiscountStrategy();
        cart.setDiscountStrategy(blackFridayDiscount);
        amount = 200.0;
        totalAmount = cart.calculateTotalAmount(amount);
        System.out.println("Total amount after discount: " + totalAmount);
    }
}