设计模式之策略模式

/**
 * 抽象策略接口
 */
public interface IStrategy {
    /**
     * 定义一个计算商品价格的接口
     * @param orginPrice
     * @return
     */
    double calPrice(double orginPrice);
}

/**
 * 普通会员策略实现
 * 没有优惠，按原价计算
 */
public class NormalStrategy implements IStrategy {
    @Override
    public double calPrice(double orginPrice) {
        return orginPrice;
    }
}

/**
 * 黄金会员策略实现
 * 按9折计价
 */
public class GoldStrategy implements IStrategy{
    @Override
    public double calPrice(double orginPrice) {
        return orginPrice * 0.9;
    }
}

/**
 * Plus 会员策略实现
 * Plus 按8折计价，如果折后价大于100，可以使用10块钱的优惠券
 */
public class PlusStrategy implements IStrategy {
    @Override
    public double calPrice(double orginPrice) {
        double reamPrice = orginPrice * 0.8;
        if (reamPrice > 100) {
            reamPrice = reamPrice - 10;
        }
        return reamPrice;
    }
}

/**
 * 包装算法策略的使用
 */
public class Context {
    private IStrategy strategy;

    public IStrategy getStrategy() {
        return strategy;
    }

    public void setStrategy(IStrategy strategy) {
        this.strategy = strategy;
    }

    /**
     * 调用具体策略计算商品价格
     * @param orginPrice
     * @return
     */
    public double calPrice(double orginPrice) {
        return strategy.calPrice(orginPrice);
    }
}

/**
 * 模拟客户端调用策略
 */
public class MainTest {
    public static void main(String[] args) {
        IStrategy normalStrategy = new NormalStrategy();
        IStrategy goldStrategy = new GoldStrategy();
        IStrategy plusStrategy = new PlusStrategy();

        Context context = new Context();
        context.setStrategy(normalStrategy);
        double result = context.calPrice(153.32);
        System.out.println("normal price= " + result);

        context.setStrategy(goldStrategy);
        result = context.calPrice(153.32);
        System.out.println("gold price= " + result);

        context.setStrategy(plusStrategy);
        result = context.calPrice(153.32);
        System.out.println("plus price= " + result);
    }
}

4、运行结果