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
    }
}