java - 我正在尝试使用 Java 8 在下面的代码片段中实现策略设计模式。寻找更好的实现方法？

Question

我有以下服务实现:-

package Java8.controller;

import java.util.function.Function;

public class ServiceImpl implements ITicket {

    Function<Integer,Double> ticketCal;

    public ServiceImpl(Function<Integer,Double> ticketCal){
        this.ticketCal= ticketCal;
    }

    @Override
    public double calculateFare(int quantity) {
        return ticketCal.apply(quantity);
    }

}

以下是我创建的策略:-

躺椅票攻略:-

package Java8.controller;

import java.util.function.Function;

public interface ReclinerTicketStrategy {

    default Function<Integer,Double> reclinerTicketStrategy(){

        return (noOfTickets)->{
            return noOfTickets * 200.00;
        };
    }
}

VIP票攻略:-

package Java8.controller;

import java.util.function.Function;

public interface VipTicketStrategy {

    default Function<Integer,Double> vipTicketStrategy(){

         return (noOfTickets)->{
             return noOfTickets*400.00;
        };

    }
}

下面是使用该策略的主类:-

package Java8.controller;

public class Main implements ReclinerTicketStrategy {

    public Main(){

        ITicket ticketsVip = new ServiceImpl(reclinerTicketStrategy());
        System.out.println(ticketsVip.calculateFare(5));

}

    public static void main(String args[]){
        Main main = new Main();
    }


}

我的问题是，这是否是将策略函数作为默认方法放置在界面中的正确方法？或者有更好的方法吗？

Answer 1

策略应该实现服务所需的抽象。在这种情况下，服务需要 Function<Integer,Double>那么一个策略就是……

class ReclinerTicketStrategy implements Function<Integer,Double> {
    @Override
    public Double apply(Integer noOfTickets) {
        return noOfTickets * 200.0;
    }
}

然后服务被实例化为，
ITicket reclinerTicket = new ServiceImpl(new ReclinerTicketStrategy());

当然，如果不需要复用策略，那么一个lambda就足够了。
ITicket reclinerTicket = new ServiceImpl(noOfTickets -> noOfTickets * 200.0);