Java设计模式之简单工厂设计模式

　　简单工厂将业务逻辑部分和界面逻辑部分分离开来，降低了界面逻辑和业务逻辑的耦合度，符合面向对象迪米特法则。下面以一个加法减法运算器为例，各位读者可以自行按照这种设计方式设计出一个小小的运算器。

1、业务逻辑

1.1、父类Operation

 1 package com.designmode.simplefactory;
 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、加法子类AddOperation

 1 package com.designmode.simplefactory;
 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、减法子类SubOperation

 1 package com.designmode.simplefactory;
 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、生成对象工厂

 1 package com.designmode.simplefactory;
 2 
 3 public class OperationFactory {
 4 
 5     /**
 6      * 创建对象工厂
 7      * @param operate 运算符
 8      * @return 运算对象
 9      */
10     public static Operation createOperation(String operate){
11         Operation operation = null;
12         switch (operate) {
13         case "+":
14             operation = new AddOperation();
15             break;
16         case "-":
17             operation = new SunOperation();
18             break;
19         default:
20             System.out.println("请输入正确的运算符!");
21             break;
22         }
23         return operation;
24     }
25 }

2、页面逻辑

 1 package com.designmode.simplefactory;
 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         Operation operation = OperationFactory.createOperation(operate); // 生成运算对象
18         operation.setValue(numberA, numberB); // 设置numberA与numberB的值
19         int result = operation.getResult(); // 获取运算结果
20         System.out.println(numberA+operate+numberB+"="+result); // 打印运算结果
21     }
22 }