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@Overridepublic 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@Overridepublic 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@Overridepublic 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