工厂方法模式

最新推荐文章于 2025-10-17 10:18:55 发布

原创最新推荐文章于 2025-10-17 10:18:55 发布 · 178 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#设计模式

设计模式专栏收录该内容

19 篇文章

订阅专栏

1.案例1-计算器实现

接上文简单方法模式例子：

https://blog.youkuaiyun.com/single_wolf_wolf/article/details/78702232

工厂方法模式结果图如下：

新增公共工厂接口和每种操作的工厂类

//工厂方式模式-简单工厂进阶
public interface IFactory {

    public Operation createOperation();
}


//加减乘除各自建立一个工厂类
public class AddFactory implements  IFactory {

    @Override
    public Operation createOperation(){
        return new OperationAdd();
    }
}


public class SubFactory implements IFactory {

    @Override
    public Operation createOperation(){
        return new OperationSub();
    }
}


public class MulFactory implements IFactory {

    @Override
    public Operation createOperation(){
        return  new OperationMul();
    }
}


public class DivFactory implements IFactory {

    @Override
    public Operation createOperation(){
        return new OperationDiv();
    }
}

测试一下：

public class ClientMainTest {

    public static  void main(String[] args){
        IFactory iFactory = new AddFactory();
        Operation operation = iFactory.createOperation();
        operation.set_numberA(2);
        operation.set_numberB(5);
        System.out.println(operation.getResult());
    }
}

/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA CE.app/Contents/lib/idea_rt.jar=50111:/Applications/IntelliJ IDEA CE.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/tools.jar:/Users/liuxuwei/IdeaProjects/dahuadesignmodel/out/production/dahuadesignmodel factorymethodmodel5.ClientMainTest
7.0

Process finished with exit code 0

同样一个案例，简单工厂模式比工厂模式简单很多，那么，为什么还会有工厂模式呢？

原因如下：

简单工厂模式最大的优点是在于工厂类中包含了必要的逻辑判断，根据客户端的选择条件动态实例化相关的类，对于客户端来说，去除了产品的依赖。

工厂方法模式，定义了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子类。

如果我们给此方法增加一个功能，求X得Y次方，如果按照简单工厂模式，需要修改运算工厂类中的case分支，从而违背了开发-封闭原则，如果是工厂方法模式，我们只是需要增加该功能的运算类和运算工厂类就可以了，是扩展了变化，而不是修改了变化，符合开发-封闭原则。

但是就此案例来说，简单工厂模式，把内部逻辑判断放到了工厂类中进行，工厂方法模式，是放到了客户端进行，即在客户端进行选择具体使用哪个具体的运算。

2.例子2 《大话设计模式》中雷锋工厂

大学生，社区志愿者都可以是雷锋，以此建立了雷锋工厂

public class LeiFeng {

    public void Sweep(){
        System.out.println("扫地");
    }

    public void Wash(){
        System.out.println("洗衣服");
    }

    public void BuyRice(){
        System.out.println("买米");
    }

}


public interface IFactory {

    public LeiFeng createLeiFeng();
}

public class UnderGraduate  extends  LeiFeng{

}

public class UnderGraduateFactory implements IFactory {

    @Override
    public LeiFeng createLeiFeng(){
        return new UnderGraduate();
    }
}

public class Volunteer extends  LeiFeng {
}


public class VolunteerFactory implements IFactory {

    @Override
    public LeiFeng createLeiFeng(){
        return new Volunteer();
    }
}

public class LeifengTestMain {

    public static  void main(String[] args){
        IFactory factory = new UnderGraduateFactory();
        LeiFeng student = factory.createLeiFeng();
        student.BuyRice();
        student.Sweep();
        student.Wash();

        IFactory factory2 = new VolunteerFactory();
        LeiFeng volunteer = factory2.createLeiFeng();
        volunteer.Wash();
        volunteer.Sweep();
        volunteer.BuyRice();
    }
}

结果：

买米
扫地
洗衣服
洗衣服
扫地
买米

Process finished with exit code 0

参考《大话设计模式》