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java設計模式之簡單工廠

package com.jiangwg.psj.design;


import java.util.Scanner;

/**
 * @Auther: Peng Senjie
 * @Date: 2018-09-14
 * @Description: 簡單工廠模式
 */
public class Jiandangongchang {

    public static void main(String[] args) {
        //one();//一般
        //two();//進階:封裝。業務介面分開,複用性,
        //three();//繼承多型,鬆耦合,增加一個分支,如開根號演算法,為了不影響原來方法,
        four();//簡單工廠模式,加減演算法用一個類去代理
    }


    private static void one(){
        Scanner sc = new Scanner(System.in);
        System.out.println("請輸入數字A:");
        String numberA = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入運算子:");
        String strOperate = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入數字B:");
        String numberB = sc.nextLine();  //讀取字串型輸入
        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("被除數不能為0");
                }else {
                    result=v+v1;
                }
                break;
        }
        System.out.println("結果是:" + result);
    }

    private static void two(){
        Scanner sc = new Scanner(System.in);
        System.out.println("請輸入數字A:");
        String numberA = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入運算子:");
        String strOperate = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入數字B:");
        String numberB = sc.nextLine();  //讀取字串型輸入
        double result = Operation.getResult(numberA,numberB,strOperate);
        System.out.println("結果是:" + result);
    }

    private static void three(){
        Scanner sc = new Scanner(System.in);
        System.out.println("請輸入數字A:");
        String numberA = sc.nextLine();  //讀取字串型輸入
        //System.out.println("請輸入運算子:");
        //String strOperate = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入數字B:");
        String numberB = sc.nextLine();  //讀取字串型輸入
        OperationDiv operationMul = new OperationDiv();
        //todo:每次都要實列化物件(符號也沒了。),能不能根據符號自動實列話出相應的物件呢(用單獨類去代理例項化的過程)---》簡單工廠
        operationMul.setNewA(Double.parseDouble(numberA));
        operationMul.setNewB(Double.parseDouble(numberB));
        double result = operationMul.getResult();
        System.out.println("結果是:" + result);
    }

    private static void four(){
        Scanner sc = new Scanner(System.in);
        System.out.println("請輸入數字A:");
        String numberA = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入運算子:");
        String strOperate = sc.nextLine();  //讀取字串型輸入
        System.out.println("請輸入數字B:");
        String numberB = sc.nextLine();  //讀取字串型輸入
        OperationTwo op = OperationFactory.createOp(strOperate);
        op.setNewA(Double.parseDouble(numberA));
        op.setNewB(Double.parseDouble(numberB));
        double result = op.getResult();
        System.out.println("結果是:" + 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("被除數不能為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("被除數不能為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;
    }
}