Java设计模式之工厂设计模式

工厂模式（Factory Method）：定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到了子类。

1、业务逻辑

1.1、父类Operation

 1 package com.designmode.factory;
 2 
 3 public abstract class Operation {
 4 
 5     protected int numberA;
 6     protected int numberB;
 7     
 8     public void setValue(int numberA,int numberB){
 9         this.numberA=numberA;
10         this.numberB=numberB;
11     }
12     
13     public abstract int getResult();
14 }

1.2、加法类AddOperation

 1 package com.designmode.factory;
 2 
 3 public class AddOperation extends Operation {
 4 
 5     @Override
 6     public int getResult() {
 7         // TODO Auto-generated method stub
 8         return this.numberA+this.numberB;
 9     }
10 
11 }

1.3、减法类SubOperation

 1 package com.designmode.factory;
 2 
 3 public class SunOperation extends Operation {
 4 
 5     @Override
 6     public int getResult() {
 7         // TODO Auto-generated method stub
 8         return this.numberA-numberB;
 9     }
10 
11 }

1.4、工厂父类OperationFactory

 1 package com.designmode.factory;
 2 
 3 public interface OperationFactory {
 4 
 5     /**
 6      * 创建对象工程
 7      * @param operate
 8      * @return
 9      */
10     Operation createOperation(String operate);
11     
12 }

1.5、生成加法运算对象工厂AddOperation

 1 package com.designmode.factory;
 2 
 3 public class AddFactory implements OperationFactory {
 4 
 5     @Override
 6     public Operation createOperation(String operate) {
 7         // TODO Auto-generated method stub
 8         return new AddOperation();
 9     }
10     
11 }

1.6、生成减法运算对象工厂SubOperation

 1 package com.designmode.factory;
 2 
 3 public class SubFactory implements OperationFactory {
 4 
 5     @Override
 6     public Operation createOperation(String operate) {
 7         // TODO Auto-generated method stub
 8         return new SunOperation();
 9     }
10 
11 }

2、页面逻辑

 1 package com.designmode.factory;
 2 
 3 import java.util.Scanner;
 4 
 5 public class OperationTest {
 6 
 7     @SuppressWarnings("resource")
 8     public static void main(String[] args) {
 9         Scanner reader = new Scanner(System.in);
10         System.out.print("请您输入第一个数字：");
11         int numberA = Integer.parseInt(reader.nextLine());
12         System.out.print("请您输入运算符：");
13         String operate = reader.nextLine();
14         System.out.print("请您输入第二个数字：");
15         int numberB = Integer.parseInt(reader.nextLine());
16         
17         OperationFactory operationFactory = null;
18         switch (operate) {
19         case "+":
20             operationFactory = new AddFactory();
21             break;
22         case "-":
23             operationFactory = new SubFactory();
24             break;
25         default:
26             System.out.println("你输入错误，请重新输入!");
27             break;
28         }
29         Operation operation = operationFactory.createOperation(operate); // 生成运算对象
30         operation.setValue(numberA, numberB); // 设置numberA与numberB的值
31         int result = operation.getResult(); // 获取运算结果
32         System.out.println(numberA+operate+numberB+"="+result); // 打印运算结果
33     }
34 }