工厂模式（初学）

工厂模式

1、简单工厂模式

• 是一种创建型设计模式，旨在通过一个工厂类（简单工厂）来封装对象的实例化过程

运算类

public class Operation {   //这个是父类
	private double num1;  //运算器中的两个值
	private double num2;
	public double getNum1() {
		return num1;
	}
	public void setNum1(double num1) {
		this.num1 = num1;
	}
	public double getNum2() {
		return num2;
	}
	public void setNum2(double num2) {
		this.num2 = num2;
	}
	
	public double getResult() {  //用于子类获取结果
		double result = 0;
		return result;
	}
}

加减乘类

public class OperationAdd extends Operation{  //加法

	@Override
	public double getResult() {
		double result = 0;
		result = super.getNum1() + super.getNum2();  //从父类获取值
		return result;
	}
}

public class OperationSub extends Operation{ //减法

	@Override
	public double getResult() { 
		double result = 0;
		result = super.getNum1() - super.getNum2();  //从父类获取值
		return result;
	}  
}

public class OperationMul extends Operation{//乘法

	@Override
	public double getResult() {
		double result = 0;
		result = super.getNum1() * super.getNum2();  //从父类获取值
		return result;
	}  
}

工厂类

public class OperationFactory {
	
	public static Operation createOperation(String operate) {    //这个是个工厂类
		
		Operation op = null;   //这个为null是因为要通过符号来确定子类对象
		switch (operate) {     //判断符号，实例合适的对象
		case "+":
			op = new OperationAdd();
			break;
		case "-":
			op = new OperationSub();
			break;
		case "*":
			op = new OperationMul();
			break;
		}
		return op;
	}
}

Main

public class Main {
	public static void main(String[] args) {
		Operation op = new OperationAdd();
		op = OperationFactory.createOperation("*");   //只要输出合适的计算符号，工厂类就会实例出该有的对象
		op.setNum1(1);
		op.setNum2(2);
		double rusult = op.getResult();
		System.out.println(rusult);
	}
}

2、工厂模式实现