yilai/PercentageDiscountStrategy.java

/**
 * 百分比折扣策略，按照订单金额的百分比计算折扣
 */
package com.orderprocessing;

public class PercentageDiscountStrategy implements DiscountStrategy {
    private double percentage;
    
    /**
     * 构造方法
     * @param percentage 折扣百分比（如0.1表示10%折扣）
     */
    public PercentageDiscountStrategy(double percentage) {
        if (percentage < 0 || percentage > 1) {
            throw new IllegalArgumentException("折扣百分比必须在0到1之间");
        }
        this.percentage = percentage;
    }
    
    @Override
    public double calculateDiscount(Order order) {
        if (order == null) {
            return 0;
        }
        return order.getTotalAmount() * percentage;
    }
    
    public double getPercentage() {
        return percentage;
    }
    
    public void setPercentage(double percentage) {
        if (percentage < 0 || percentage > 1) {
            throw new IllegalArgumentException("折扣百分比必须在0到1之间");
        }
        this.percentage = percentage;
    }
}