策略模式Strategy

public interface Strategy {
    public double getPrice(double standardPrice);
}

public class OldCustomManyStrategy implements Strategy{
    @Override
    public double getPrice(double standardPrice) {
        System.out.println("老客户大批量，打8折");
        return standardPrice*0.8;
    }
}

public class OldCustomFewStrategy implements Strategy{
    @Override
    public double getPrice(double standardPrice) {
        System.out.println("老客户小批量，打85折");
        return standardPrice*0.85;
    }
}
public class NewCustomManyStrategy implements Strategy{
    @Override
    public double getPrice(double standardPrice) {
        System.out.println("新客户大批量，打9折");
        return standardPrice*0.9;
    }
}
public class NewCustomFewStrategy implements Strategy{
    @Override
    public double getPrice(double standardPrice) {
        System.out.println("新客户小批量，不打折");
        return standardPrice;
    }
}

/**
 * 负责和具体的算法交互
 * 如此，具体的算法和直接的客户端调用分离了，使得算法可以独立与客户端独立的变化
 * 如果使用Spring的依赖注入功能，可以通过配置文件动态的注入不同的策略对象，动态的切换不同的算法
 * @author tqq
 * @date 2021-04-02-10:39
 */
public class Context {
    private Strategy strategy;//当前采用的算法对象

    //通过构造器注入
    public Context(Strategy strategy) {
        this.strategy = strategy;
    }
    //通过set注入
    public void setStrategy(Strategy strategy) {
        this.strategy = strategy;
    }
    public void printPrice(double s){
        System.out.println("你的报价为："+strategy.getPrice(s));
    }
}

public class Client{
    public static void main(String[] args) {
        Strategy s1 = new OldCustomFewStrategy();
        Context context = new Context(s1);
        context.printPrice(100);
    }
}