Java学习笔记——设计模式之一.简单工厂

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　　　　　　　　　　　　　　　　　——蜀道难

类图：

定义Operation类

package cn.no1.simplefactory;

public abstract class Operation {

    private double numA;
    private double numB;

    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 abstract double calculate ();
}

定义其四个子类

package cn.no1.simplefactory;

public class OperationAdd extends Operation{

    @Override
    public double calculate() {
        // TODO Auto-generated method stub
        return this.getNumA() + this.getNumB();
    }

}
public class OperationSub extends Operation {

    @Override
    public double calculate() {
        // TODO Auto-generated method stub
        return this.getNumA()-this.getNumB();
    }

}
public class OperationMultiply extends Operation{

    @Override
    public double calculate() {
        // TODO Auto-generated method stub
        return this.getNumA()*this.getNumB();
    }
    
}
public class OperationDivide extends Operation{

    @Override
    public double calculate() {
        // TODO Auto-generated method stub
        return this.getNumA()/this.getNumB();
    }

}

定义工厂类

package cn.no1.simplefactory;

public class OperationFactory {

    public static Operation createOperation(String operator){
        Operation operation = null;
        switch (operator) {
        case "+":
            operation = new OperationAdd();
            break;
        case "-":
            operation = new OperationSub();
            break;
        case "*":
            operation = new OperationMultiply();
            break;
        case "/":
            operation = new OperationDivide();
            break;
　　　　 }
        return operation;
    }
}

测试类:

package cn.no1.simplefactory;

import java.util.Scanner;

public class _Test {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入数字1:");
        double numA = sc.nextDouble();
        System.out.println("输入数字2:");
        double numB = sc.nextDouble();
        System.out.println("输入操作符:");
        String operator = sc.next();
        sc.close();
        Operation operation = OperationFactory.createOperation(operator);
        operation.setNumA(numA);
        operation.setNumB(numB);
        double result = operation.calculate();
        System.out.println("计算结果是:"+result);
    }
}