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

 package com.designmode.factory;

 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、加法类AddOperation

 package com.designmode.factory;

 public class AddOperation extends Operation {

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

 }

1.3、减法类SubOperation

 package com.designmode.factory;

 public class SunOperation extends Operation {

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

 }

1.4、工厂父类OperationFactory

 package com.designmode.factory;

 public interface OperationFactory {

     /**
      * 创建对象工程
      * @param operate
      * @return
      */
     Operation createOperation(String operate);

 }

1.5、生成加法运算对象工厂AddOperation

 package com.designmode.factory;

 public class AddFactory implements OperationFactory {

     @Override
     public Operation createOperation(String operate) {
         // TODO Auto-generated method stub
         return new AddOperation();
     }

 }

1.6、生成减法运算对象工厂SubOperation

 package com.designmode.factory;

 public class SubFactory implements OperationFactory {

     @Override
     public Operation createOperation(String operate) {
         // TODO Auto-generated method stub
         return new SunOperation();
     }

 }

2、页面逻辑

 package com.designmode.factory;

 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());

         OperationFactory operationFactory = null;
         switch (operate) {
         case "+":
             operationFactory = new AddFactory();
             break;
         case "-":
             operationFactory = new SubFactory();
             break;
         default:
             System.out.println("你输入错误，请重新输入!");
             break;
         }
         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
     }
 }