设计模式 - 行为型模式 - 策略模式

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//电影票类：环境类
class MovieTicket {
    private double price;
    private Discount discount; //维持一个对抽象折扣类的引用

    public void setPrice(double price) {
        this.price = price;
    }

    //注入一个折扣类对象
    public void setDiscount(Discount discount) {
        this.discount = discount;
    }

    public double getPrice() {
        //调用折扣类的折扣价计算方法
        return discount.calculate(this.price);
    }
}

//折扣类：抽象策略类
interface Discount {
    public double calculate(double price);
}

//学生票折扣类：具体策略类
class StudentDiscount implements Discount {
    public double calculate(double price) {
        System.out.println("学生票：");
        return price * 0.8;
    }
}

//儿童票折扣类：具体策略类
class ChildrenDiscount implements Discount {
    public double calculate(double price) {
        System.out.println("儿童票：");
        return price - 10;
    }
}

//VIP会员票折扣类：具体策略类
class VIPDiscount implements Discount {
    public double calculate(double price) {
        System.out.println("VIP票：");
        System.out.println("增加积分！");
        return price * 0.5;
    }
}

class Client {
    public static void main(String args[]) {
        MovieTicket mt = new MovieTicket();
        double originalPrice = 60.0;
        double currentPrice;
        mt.setPrice(originalPrice);
        System.out.println("原始价为：" + originalPrice);
        System.out.println("---------------------------------");
        Discount discount;
        discount = (Discount) XMLUtil.getBean(); //读取配置文件并反射生成具体折扣对象
        mt.setDiscount(discount); //注入折扣对象
        currentPrice = mt.getPrice();
        System.out.println("折后价为：" + currentPrice);
    }
}