设计模式之——简单工厂设计模式

来源：互联网发布：网络课程运营编辑：程序博客网时间：2024/05/01 23:43

简单工厂模式严格意义上不是一种设计模式，它是工厂设计模式的一个特殊实现，又称为静态工厂方法模式，说白了就是由一个工厂对象决定创建出哪一种产品类的实例。一个是工厂类Creator负责生产产品的逻辑判断，一个是产品接口（或者抽象类）IProduct定义了产品通用的属性/操作，为了使工厂类能够知道我们需要哪一种产品，我们需要在创建产品时传递给工厂类一个参数，去表明我们想要创建哪种产品。下面是范例：

举个栗子，如果我们想写一个计算器，首先写出了加法运算，然后又想写一个减法......这么多运算如果扩展起来维护肯定捉襟见肘。所以我们考虑，这些都是运算，我定义一个抽象类Operation,里面直接返回运算的结果，具体如何实现的由实现它的子类具体实现，然后定义一个生产运算的工厂，当需要什么运算给工厂发送个信号生产出相应的运算。这样如果新的运算扩展只需要继承“运算”类，自己该怎么实现就怎么实现，各个运算间互不影响，维护起来也方便。

运算抽象类Operation

package com.zndroid.dm.FactoryModel.EasyFactory;/** * Created by luzhenyu on 2016/8/15. */public abstract class Operation {    protected double numA;    protected double numB;    public void setNumA(double numA) {        this.numA = numA;    }    public void setNumB(double numB) {        this.numB = numB;    }    public abstract double getResult();}

具体运算实现

package com.zndroid.dm.FactoryModel.EasyFactory.impl;import com.zndroid.dm.FactoryModel.EasyFactory.Operation;/** * Created by luzhenyu on 2016/8/15. */public class AddOperator extends Operation {    @Override    public double getResult() {        return numA + numB;    }}

package com.zndroid.dm.FactoryModel.EasyFactory.impl;import com.zndroid.dm.FactoryModel.EasyFactory.Operation;/** * Created by luzhenyu on 2016/8/15. */public class DivisionOperator extends Operation {    @Override    public double getResult() {        return numA / numB;    }}

运算工厂Factory

package com.zndroid.dm.FactoryModel.EasyFactory;import com.zndroid.dm.FactoryModel.EasyFactory.impl.AddOperator;import com.zndroid.dm.FactoryModel.EasyFactory.impl.DivisionOperator;/** * Created by luzhenyu on 2016/8/13. */public class Easyfactory {    public static Operation createOperation (String operator) {        Operation mOpration = null;        if ("".equals(operator) || null == operator)            return null;        switch (operator){            case "+":                mOpration = new AddOperator();                break;            case "/":                mOpration = new DivisionOperator();                break;        }        return mOpration;    }}

使用：

package com.lzy.zndroid;import com.zndroid.dm.FactoryModel.EasyFactory.Easyfactory;import com.zndroid.dm.FactoryModel.EasyFactory.Operation;import com.zndroid.dm.SingletonModel.SingletonModel;public class Demo {    public static void main(String[] args){        log("========================================");        SingletonModel s1 = SingletonModel.getInstance();        SingletonModel s2 = SingletonModel.getInstance();        log("" + (s1 == s2));        log("----------------我是分割线-----------------");        Operation addOperator = Easyfactory.createOperation("+");        addOperator.setNumA(100);        addOperator.setNumB(150);        log(addOperator.getResult() + "");        Operation divisionOperator = Easyfactory.createOperation("/");        divisionOperator.setNumA(888);        divisionOperator.setNumB(4);        //Demo暂时不考虑被除数为“0”的情况        log(divisionOperator.getResult() + "");        log("----------------我是分割线-----------------");        log("========================================");    }    private static void log(String msg) {        System.out.println("[ " + msg + " ]");    }}

总闻到一点不好的味道，代码出现在哪里呢？

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