工厂模式在开发中的运用

写一个简单的计算器

　　缺点：完全面向过程设计，缺少代码重用

加法运算

//加法运算,返回结果
public class AddOperation extends Operation {

    public double getResult() {
        double result = this.getNum1() + this.getNum2();
        return result;
    }
}

减法运算

//减法运算
public class SubtractionOperation extends Operation {

    public double getResult() {
        double result = this.getNum1() - this.getNum2();
        return result;
    }
}

运算类

//运算类 抽象类
public abstract class Operation {
    private double num1;
    private double num2;

    public double getNum1() {
        return num1;
    }

    public void setNum1(double num1) {
        this.num1 = num1;
    }

    public double getNum2() {
        return num2;
    }

    public void setNum2(double num2) {
        this.num2 = num2;
    }

    public abstract double getResult();
}

运算工厂接口

//运算工厂接口
public interface OperationFactory {
    public Operation getOperation();
}

主方法测试

import java.util.Scanner;
//主方法测试
public class MainClass {
    public static void main(String[] args) {
        //1.接受控制台输入
        System.out.println("---计算器程序---");
        System.out.println("输入第一个操作数");
        Scanner scanner = new Scanner(System.in);
        String strNum1 = scanner.nextLine();
        
        System.out.println("输入运算符");
        String oper = scanner.nextLine();
        
        System.out.println("输入第二个操作数");
        String strNum2 = scanner.nextLine();
        double result = 0;
        double num1 = Double.parseDouble(strNum1);
        double num2 = Double.parseDouble(strNum2);
        
        //2.进行运算
        if("+".equals(oper)) {
            OperationFactory factory = new AddOperationFactory();
            Operation operation = factory.getOperation();
            operation.setNum1(num1);
            operation.setNum2(num2);
            result = operation.getResult();
        }
        
        //3.返回结果
        System.out.println(strNum1 + oper + strNum2 + "=" + result);
    }
}