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;
  	}
  }
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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;
  	}
  }
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• 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;
  	}  
  }
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• 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;
  	}  
  }
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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;
  	}
  }
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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);
  	}
  }
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2、工厂模式实现