单一原则+工厂模式

package com.single;

/**
 * @author: 肖德子裕
 * @date: 2018/9/26 11:27
 * @description: 单一设计原则
 */
public class Coluculator {
    private double numA=0;
    private double numB=0;

    public double getNumA() {
        return numA;
    }

    public void setNumA(double numA) {
        this.numA = numA;
    }

    public double getNumB() {
        return numB;
    }

    public void setNumB(double numB) {
        this.numB = numB;
    }

    public double getResult(){
        double result=0;
        return result;
    }
}

package com.single;

import com.single.calculate.OperationAdd;
import com.single.calculate.OperationDiv;
import com.single.calculate.OperationMul;
import com.single.calculate.OperationSub;

/**
 * @author: 肖德子裕
 * @date: 2018/9/26 11:57
 * @description: 工厂
 */
public class OperationFactory {
    public static Coluculator creatOperate(String operate){
        Coluculator coluculator=null;
        switch (operate){
            case "+":
                coluculator=new OperationAdd();
                break;
            case "-":
                coluculator=new OperationSub();
                break;
            case "*":
                coluculator=new OperationMul();
                break;
            case "/":
                coluculator=new OperationDiv();
                break;
                default:
                    throw new RuntimeException("运算符不合法");
        }
        return coluculator;
    }
}

package com.single.calculate;

import com.single.Coluculator;

/**
 * @author: 肖德子裕
 * @date: 2018/9/26 11:49
 * @description: 加法运算
 */
public class OperationAdd extends Coluculator {
    @Override
    public double getResult() {
       double result=0;
       return result=getNumA()+getNumB();
    }
}

package com.single.calculate;

import com.single.Coluculator;

/**
 * @author: 肖德子裕
 * @date: 2018/9/26 11:49
 * @description: 除法运算
 */
public class OperationDiv extends Coluculator {
    @Override
    public double getResult() {
       double result=0;
       if(getNumB()==0){
          throw new RuntimeException("分母不能为0");
       }
       return result=getNumA()/getNumB();
    }
}

package com.single;

import org.junit.Test;

/**
 * @author: 肖德子裕
 * @date: 2018/9/26 11:41
 * @description: 测试四则运算
 */
public class Main {
    @Test
    public void testAdd(){
        Coluculator coluculator=OperationFactory.creatOperate("+");
        coluculator.setNumA(20);
        coluculator.setNumB(20);
        double result=coluculator.getResult();
        System.out.println(result);
    }

    @Test
    public void testSub(){
        Coluculator coluculator=OperationFactory.creatOperate("-");
        coluculator.setNumA(40);
        coluculator.setNumB(20);
        double result=coluculator.getResult();
        System.out.println(result);
    }

    @Test
    public void testMul(){
        Coluculator coluculator=OperationFactory.creatOperate("*");
        coluculator.setNumA(40);
        coluculator.setNumB(20);
        double result=coluculator.getResult();
        System.out.println(result);
    }

    @Test
    public void testDiv(){
        Coluculator coluculator=OperationFactory.creatOperate("/");
        coluculator.setNumA(40);
        coluculator.setNumB(20);
        double result=coluculator.getResult();
        System.out.println(result);
    }
}