简单工厂模式---计算器

前言：一点一点的积累吧。如果文章中，有不恰当的地方，还请指正。之前看过《大话设计模式》，今天通过手敲代码进一步加深理解简单工厂模式！

下面是我按照我的思路的实现，有的步骤，谁在前谁在后都无所谓。

1.抽象出相同的属性和方法。这里可以用接口，也可以用抽象类。在开发中接口用的比较多。

package ch06;

/**
 * @ClassName Operation
 * @Description TODO
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午8:52:43
 */
public abstract class Operation {
	private double numberA;
	private double numberB;
	
	public Operation(){
		
	}
	public Operation(double numberA,double numberB){
		this.numberA = numberA;
		this.numberB = numberB;
	}
	
	
	/**
	 * @param numberA the numberA to set
	 */
	public void setNumberA(double numberA) {
		this.numberA = numberA;
	}
	/**
	 * @param numberB the numberB to set
	 */
	public void setNumberB(double numberB) {
		this.numberB = numberB;
	}
	public double getNubmerA(){
		return this.numberA;
	}
	public double getNumberB(){
		return this.numberB;
	}
	public abstract double getResult();//需要重写的方法。
}

2.实现各种具体操作，比如简单的加减乘除。

package ch06;

/**
 * @ClassName Addtion
 * @Description 加法类
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午9:29:26
 */
public class Addtion extends Operation{

	public Addtion(){
		
	}
	/**
	 * @param numberA
	 * @param numberB
	 */
	public Addtion(double numberA, double numberB) {
		super(numberA, numberB);
		// TODO Auto-generated constructor stub
	}

	/* (non-Javadoc)
	 * @see ch06.Operation#getResult()
	 */
	@Override
	public double getResult() {
		// TODO Auto-generated method stub
		return super.getNubmerA()+super.getNumberB();
	}
	
}

package ch06;

/**
 * @ClassName Subtraction
 * @Description 减法类
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午9:26:31
 */
public class Subtraction extends Operation{

	public Subtraction(){
		
	}
	/**
	 * @param numberA
	 * @param numberB
	 */
	public Subtraction(double numberA, double numberB) {
		super(numberA, numberB);
		// TODO Auto-generated constructor stub
	}

	/* (non-Javadoc)
	 * @see ch06.Operation#getResult()
	 */
	@Override
	public double getResult() {
		// TODO Auto-generated method stub
		return super.getNubmerA()-super.getNumberB();
	}
	
}

package ch06;

/**
 * 
 * @ClassName Multiply
 * @Description 乘法类
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午10:58:42
 */
public class Multiply extends Operation{

	public Multiply(){
		
	}
	public Multiply(double numberA,double nubmerB){
		super(numberA,nubmerB);
	}
	/* (non-Javadoc)
	 * @see ch06.Operation#getResult()
	 */
	@Override
	public double getResult() {
		// TODO Auto-generated method stub
		return super.getNubmerA()*super.getNumberB();
	}
	
}

package ch06;

/**
 * @ClassName Divsion
 * @Description 除法类
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午10:58:32
 */
public class Divsion extends Operation{

	/* (non-Javadoc)
	 * @see ch06.Operation#getResult()
	 */
	@Override
	public double getResult() {
		// TODO Auto-generated method stub
		return super.getNubmerA()/super.getNumberB();
	}

}

3.利用静态工厂实例化具体的操作。

package ch06;

/**
 * @ClassName OperatorFactory
 * @Description 利用静态工厂实例化各种操作
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午9:34:33
 */
public class OperatorFactory {
	public static Operation createOperation(char operator){
		Operation ope = null;
		switch(operator){
			case '+': ope = new Addtion();break;
			case '-': ope = new Subtraction();break;
			case '*': ope = new Multiply();break;
			case '/': ope = new Divsion();break;
		}
		return ope;
	}
}

4.测试类；

整个程序中自己定义了构造函数，但是没有用到，原本想用过构造函数来给数值的。不能用抽象类来new一个对象，可以用它的非抽象子类来new对象。这也就是向上转型！

package ch06;

import java.util.Scanner;

/**
 * @ClassName ComputerTest
 * @Description TODO
 * @author XingZhaohu  [email protected]
 * @date 2016-4-9  下午9:44:18
 */
public class ComputerTest {
	public static void main(String[] args){
		/*
		 * 声明一下：只是为了简单的测试，并没有处理异常。
		 * */
		Operation ope = null;
		Scanner in = new Scanner(System.in);
		System.out.println("请输入数A：");
		double	numberA = in.nextDouble();
		System.out.println("请输入运算符：");
		char operator = in.next().charAt(0);//运算符
		ope = OperatorFactory.createOperation(operator);//利用静态工厂实例化对应得对象
		System.out.println("请输入数B：");
		double numberB = in.nextDouble();//数B
		ope.setNumberA(numberA);
		ope.setNumberB(numberB);
		System.out.printf("%f%c%f=%f",numberA,operator,numberB,ope.getResult());
		
		
	}
}