策略模式 Strategy Pattern

// 抽象策略角色
public interface SaleStrategy {
    double getRetailPrice(double tagPrice);
}
// 具体策略角色
public class PublicSaleStrategy implements SaleStrategy {
    @Override
    public double getRetailPrice(double tagPrice) {
        return tagPrice * 0.95D;
    }
}
public class SuperSaleStrategy implements SaleStrategy {
    @Override
    public double getRetailPrice(double tagPrice) {
        return tagPrice * 0.88D;
    }
}
public class BossStrategy implements SaleStrategy {
    @Override
    public double getRetailPrice(double tagPrice) {
        return tagPrice * 0.80D;
    }
}
// 环境角色
public class CarShop {
    private SaleStrategy saleStrategy;
    private double tagPrice = 100000.00D;
    public CarShop(SaleStrategy saleStrategy) {
        this.saleStrategy = saleStrategy;
    }
    public void getPrice() {
        System.out.println(saleStrategy.getRetailPrice(tagPrice));
    }
}
// 测试类
public class CarShopTest {
    @org.junit.Test
    public void getPrice() {
        SaleStrategy strategy = new PublicSaleStrategy();
        CarShop car = new CarShop(strategy);
        car.getPrice();
        strategy = new SuperSaleStrategy();
        car = new CarShop(strategy);
        car.getPrice();
        strategy = new BossStrategy();
        car = new CarShop(strategy);
        car.getPrice();
    }
}