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
    }
}