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

 package com.designmode.simplefactory;

 public abstract class Operation {

     protected int numberA;
     protected int numberB;

     public void setValue(int numberA,int numberB){
         this.numberA=numberA;
         this.numberB=numberB;
     }

     public abstract int getResult();
 }

1.2、加法子类AddOperation

 package com.designmode.simplefactory;

 public class AddOperation extends Operation {

     @Override
     public int getResult() {
         // TODO Auto-generated method stub
         return this.numberA+this.numberB;
     }

 }

1.3、减法子类SubOperation

 package com.designmode.simplefactory;

 public class SunOperation extends Operation {

     @Override
     public int getResult() {
         // TODO Auto-generated method stub
         return this.numberA-numberB;
     }

 }

1.4、生成对象工厂

 package com.designmode.simplefactory;

 public class OperationFactory {

     /**
      * 创建对象工厂
      * @param operate 运算符
      * @return 运算对象
      */
     public static Operation createOperation(String operate){
         Operation operation = null;
         switch (operate) {
         case "+":
             operation = new AddOperation();
             break;
         case "-":
             operation = new SunOperation();
             break;
         default:
             System.out.println("请输入正确的运算符!");
             break;
         }
         return operation;
     }
 }

2、页面逻辑

 package com.designmode.simplefactory;

 import java.util.Scanner;

 public class OperationTest {

     @SuppressWarnings("resource")
     public static void main(String[] args) {
         Scanner reader = new Scanner(System.in);
         System.out.print("请您输入第一个数字：");
         int numberA = Integer.parseInt(reader.nextLine());
         System.out.print("请您输入运算符：");
         String operate = reader.nextLine();
         System.out.print("请您输入第二个数字：");
         int numberB = Integer.parseInt(reader.nextLine());

         Operation operation = OperationFactory.createOperation(operate); // 生成运算对象
         operation.setValue(numberA, numberB); // 设置numberA与numberB的值
         int result = operation.getResult(); // 获取运算结果
         System.out.println(numberA+operate+numberB+"="+result); // 打印运算结果
     }
 }