package com.dp.simpleFactory;

//计算器作为抽象类  定义一个计算需要什么    子类继承了两个数字      并且要有自己的计算实现方法
public abstract class  Calculator {
     protected double numberA=0;
     protected double numberB=0;
    public double getNumberA() {
        return numberA;
    }
    public void setNumberA(double numberA) {
        this.numberA = numberA;
    }
    public double getNumberB() {
        return numberB;
    }
    public void setNumberB(double numberB) {
        this.numberB = numberB;
    }    
     
    
    public abstract double getResult() throws Exception;    
}


class CalculatorAdd extends Calculator 
{
    @Override
    public double getResult() {
        double result=numberA+numberB;
        return result;
    }
}


class CalculatorMinus extends Calculator 
{
    @Override
    public double getResult() {
        double result=numberA-numberB;
        return result;
    }
}



class CalculatorMultiply extends Calculator 
{
    @Override
    public double getResult() {
        double result=numberA*numberB;
        return result;
    }
}



class CalculatorDivide extends Calculator 
{
    @Override
    public double getResult() throws Exception {
        double result=numberA/numberB;
        if(numberB==0)
            throw new Exception("除数不能为0");
        return result;
    }
}


//问题是:怎么根据输入而得到指定的类？

//使用简单工厂设计模式   根据操作符得到某个类(根据xx条件得到XX类)
class CalculatorFactory
{
    public static Calculator createCalculator(String operate)
    {
       Calculator cal=null;
       switch(operate)
       {
       case "+":
               cal=new CalculatorAdd();
               break;
         
       case "-":
             cal=new CalculatorMinus();
             break;
             
             
       case "*":
             cal=new CalculatorMultiply();
             break;
             
       case "/":
             cal=new CalculatorDivide();
             break;
       }
       return cal;
    }
}

package com.dp.simpleFactory;

import java.util.Scanner;
/**
 * 客户端
 * 
 *
 */
public class Client {
   public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        System.out.println("请输入数字A");
        String numberA=in.next();
        System.out.println("请输入运算符号(ex:+ - * /)");
        String operate=in.next();
        System.out.println("请输入数字B");
        String numberB=in.next();
    //根据输入的符号得到具体的实现子类 使用到多态
        Calculator cal=CalculatorFactory.createCalculator(operate);
        cal.setNumberA(Double.parseDouble(numberA));
        cal.setNumberB(Double.parseDouble(numberB));
        double result=0;
        
        try {
            result = cal.getResult();
        } catch (Exception e) {
            System.out.println("除数不能为0");
        }
        System.out.println(result);
    
   }
}