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
}
}