设计模式-策略模式

策略模式，多判断情况：根据顾客判断打折优惠

定义接口，抽象策略角色，以供策略角色使用
public interface Strategy {
	public double getPrice(double standardPrice);
}

角色1
public class NewCustomerFewStrategy implements Strategy {
	@Override
	public double getPrice(double standardPrice) {
		System.out.println("不打折，原价");
		return standardPrice;
	}
}

角色2
public class NewCustomerManyStrategy implements Strategy {

	@Override
	public double getPrice(double standardPrice) {
		System.out.println("打九折");
		return standardPrice*0.9;
	}
}

定义和策略角色交互的环境。构造方法用多态的方式接收策略角色
public class Context {
	private Strategy strategy;	//当前采用的算法对象
	//可以通过构造器来注入
	public Context(Strategy strategy) {
		super();
		this.strategy = strategy;
	}
	//可以通过set方法来注入
	public void setStrategy(Strategy strategy) {
		this.strategy = strategy;
	}
	public void pringPrice(double s){
		System.out.println("您该报价："+strategy.getPrice(s));
	}
}

使用
public class Client {
	public static void main(String[] args) {
		
		Strategy s1 = new OldCustomerManyStrategy();
		Context ctx = new Context(s1);
		ctx.pringPrice(500);
	}
}