优点：
1.不用自己再去new对象，工厂会根据给的标识，自动替你new出一个你想要的实现类对象。
2.一定程度上在加减乘除之间实现了解耦合。提高了代码的复用性和扩展性。
一、整体思想图：
二、代码实现
2.1 父类
package com.design.bean;
/**
* 简单工厂模式——父类（抽取固定模块）
* @author phoebe
*
*/
public class CaculateBean {
private double a;
private double b;
private double result;
public double getA() {
return a;
}
public void setA(double a) {
this.a = a;
}
public double getB() {
return b;
}
public void setB(double b) {
this.b = b;
}
public double getResult() {
return result;
}
public void setResult(double result) {
this.result = result;
}
}
2.2 加法模块：
package com.design.calimpl;
import com.design.bean.CaculateBean;
/**
* 加法模块
* @author phoebe
*
*/
public class Caculate_add extends CaculateBean {
@Override
public double getResult() {
return this.getA()+this.getB();
}
}
2.3减法模块/乘法模块/除法模块和加法模块一样
2.4产生具体实例化对象工厂
package com.design.factory;
import com.design.bean.CaculateBean;
import com.design.calimpl.Caculate_add;
import com.design.calimpl.Caculate_div;
import com.design.calimpl.Caculate_multi;
import com.design.calimpl.Caculate_sub;
import com.design.util.myException;
/**
* 控制具体采用哪一个实现类
* @author phoebe
*
*/
public class CaculateFactory {
public static CaculateBean getBeanFactory(String str){
switch(str){
case "+" :
return new Caculate_add();
case "-" :
return new Caculate_sub();
case "*" :
return new Caculate_multi();
case "/" :
return new Caculate_div();
default:
try {
throw new myException();
} catch (myException e) {
e.printStackTrace();
}
}
return null;
}
}
2.5测试代码
package com.design.test;
import java.util.Scanner;
import com.design.bean.CaculateBean;
import com.design.factory.CaculateFactory;
/**
* 测试
* @author phoebe
*
*/
public class Test {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
double a = sc.nextDouble();
double b = sc.nextDouble();
String tig = sc.next();
CaculateBean caculateBean = CaculateFactory.getBeanFactory(tig);
caculateBean.setA(a);
caculateBean.setB(b);
System.out.println(caculateBean.getResult());
}
}
