java设计模式之简单工厂

package com.jiangwg.psj.design;


import java.util.Scanner;

/**
 * @Auther: Peng Senjie
 * @Date: 2018-09-14
 * @Description: 简单工厂模式
 */
public class Jiandangongchang {

    public static void main(String[] args) {
        //one();//一般
        //two();//进阶：封装。业务界面分开，复用性，
        //three();//继承多态,松耦合，增加一个分支，如开根号算法，为了不影响原来方法,
        four();//简单工厂模式，加减算法用一个类去代理
    }


    private static void one(){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入数字A：");
        String numberA = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入运算符：");
        String strOperate = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入数字B：");
        String numberB = sc.nextLine();  //读取字符串型输入
        double result=0.0;
        double v = Double.parseDouble(numberA);
        double v1 = Double.parseDouble(numberB);
        switch (strOperate){
            case "+":
                result=v+v1;
                break;
            case "-":
                result=v+v1;
                break;
            case "*":
                result=v+v1;
                break;
            case "/":
                if(numberB.equals("0")){
                    System.out.println("被除数不能为0");
                }else {
                    result=v+v1;
                }
                break;
        }
        System.out.println("结果是：" + result);
    }

    private static void two(){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入数字A：");
        String numberA = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入运算符：");
        String strOperate = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入数字B：");
        String numberB = sc.nextLine();  //读取字符串型输入
        double result = Operation.getResult(numberA,numberB,strOperate);
        System.out.println("结果是：" + result);
    }

    private static void three(){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入数字A：");
        String numberA = sc.nextLine();  //读取字符串型输入
        //System.out.println("请输入运算符：");
        //String strOperate = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入数字B：");
        String numberB = sc.nextLine();  //读取字符串型输入
        OperationDiv operationMul = new OperationDiv();
        //todo:每次都要实列化对象（符号也没了。），能不能根据符号自动实列话出相应的对象呢(用单独类去代理实例化的过程)---》简单工厂
        operationMul.setNewA(Double.parseDouble(numberA));
        operationMul.setNewB(Double.parseDouble(numberB));
        double result = operationMul.getResult();
        System.out.println("结果是：" + result);
    }

    private static void four(){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入数字A：");
        String numberA = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入运算符：");
        String strOperate = sc.nextLine();  //读取字符串型输入
        System.out.println("请输入数字B：");
        String numberB = sc.nextLine();  //读取字符串型输入
        OperationTwo op = OperationFactory.createOp(strOperate);
        op.setNewA(Double.parseDouble(numberA));
        op.setNewB(Double.parseDouble(numberB));
        double result = op.getResult();
        System.out.println("结果是：" + result);
    }

}


class Operation {

          static double getResult(String numberA,String numberB,String strOperate){
             double result=0.0;
             double v = Double.parseDouble(numberA);
             double v1 = Double.parseDouble(numberB);
             switch (strOperate){
                 case "+":
                     result=v+v1;
                     break;
                 case "-":
                     result=v+v1;
                     break;
                 case "*":
                     result=v+v1;
                     break;
                 case "/":
                     if(numberB.equals("0")){
                         System.out.println("被除数不能为0");
                     }else {
                         result=v+v1;
                     }
                     break;
             }
             return result;
        }
 }

class OperationTwo{

    private double newA=0.0;
    private double newB=0.0;

    public double getNewA() {
        return newA;
    }

    public void setNewA(double newA) {
        this.newA = newA;
    }

    public double getNewB() {
        return newB;
    }

    public void setNewB(double newB) {
        this.newB = newB;
    }

    public  double getResult(){
        double result=0.0;
        return result;
    }

}

class OperationAdd extends OperationTwo{

    @Override
    public double getResult() {
        double result=0.0;
        result=getNewA()+getNewB();
        return result;
    }
}

class OperationSub extends OperationTwo{

    @Override
    public double getResult() {
        double result=0.0;
        result=getNewA()-getNewB();
        return result;
    }
}

class OperationMul extends OperationTwo{

    @Override
    public double getResult() {
        double result=0.0;
        result=getNewA()*getNewB();
        return result;
    }
}

class OperationDiv extends OperationTwo{

    @Override
    public double getResult() {
        double result=0.0;
        System.out.println("getnewb:"+getNewB());
        if(Double.doubleToLongBits(getNewB())==0){
            System.out.println("被除数不能为0");
        }else{
            result=getNewA()/getNewB();
        }
        return result;
    }
}

class OperationFactory{
    public static OperationTwo createOp(String strOperate){
        double result=0.0;
        OperationTwo otwo=null;
        switch (strOperate){
            case "+":
                otwo=new OperationAdd();
                break;
            case "-":
                otwo=new OperationSub();
                break;
            case "*":
                otwo=new OperationMul();
                break;
            case "/":
                otwo=new OperationDiv();
                break;
        }
        return otwo;
    }
}