工厂模式在开发中的运用

写一个简单的计算器

　　缺点：完全面向过程设计，缺少代码重用

加法运算

1 //加法运算,返回结果
2 public class AddOperation extends Operation {
3 
4     public double getResult() {
5         double result = this.getNum1() + this.getNum2();
6         return result;
7     }
8 }

减法运算

1 //减法运算
2 public class SubtractionOperation extends Operation {
3 
4     public double getResult() {
5         double result = this.getNum1() - this.getNum2();
6         return result;
7     }
8 }

运算类

 1 //运算类 抽象类
 2 public abstract class Operation {
 3     private double num1;
 4     private double num2;
 5 
 6     public double getNum1() {
 7         return num1;
 8     }
 9 
10     public void setNum1(double num1) {
11         this.num1 = num1;
12     }
13 
14     public double getNum2() {
15         return num2;
16     }
17 
18     public void setNum2(double num2) {
19         this.num2 = num2;
20     }
21 
22     public abstract double getResult();
23 }

运算工厂接口

1 //运算工厂接口
2 public interface OperationFactory {
3     public Operation getOperation();
4 }

主方法测试

 1 import java.util.Scanner;
 2 //主方法测试
 3 public class MainClass {
 4     public static void main(String[] args) {
 5         //1.接受控制台输入
 6         System.out.println("---计算器程序---");
 7         System.out.println("输入第一个操作数");
 8         Scanner scanner = new Scanner(System.in);
 9         String strNum1 = scanner.nextLine();
10         
11         System.out.println("输入运算符");
12         String oper = scanner.nextLine();
13         
14         System.out.println("输入第二个操作数");
15         String strNum2 = scanner.nextLine();
16         double result = 0;
17         double num1 = Double.parseDouble(strNum1);
18         double num2 = Double.parseDouble(strNum2);
19         
20         //2.进行运算
21         if("+".equals(oper)) {
22             OperationFactory factory = new AddOperationFactory();
23             Operation operation = factory.getOperation();
24             operation.setNum1(num1);
25             operation.setNum2(num2);
26             result = operation.getResult();
27         }
28         
29         //3.返回结果
30         System.out.println(strNum1 + oper + strNum2 + "=" + result);
31     }
32 }