代理模式

//代理模式，用NPC帮我们做加法，减法；实际工作场景支付环境的切换，使用代理对象进行切换

public interface ICalc {
    public int calc(int i,int l);
}

public class Npc01 implements ICalc{
    @Override
    public int calc(int i, int l) {
        return i+l;
    }
}

public class Npc02 implements ICalc{
    @Override
    public int calc(int i, int l) {
        return i-l;
    }
}

public class Person {
    public ICalc iCalc;

    public int getNumber(int i,int l){
     return  iCalc.calc(i,l);
    }

}

Person person = new Person();
person.iCalc = new Npc01();
System.out.println(person.getNumber(1, 2));

person.iCalc = new Npc02();
System.out.println(person.getNumber(1, 2));