三种工厂模式介绍

简单工厂模式

定义

简单工厂模式（Simple Factory Pattern）是指由一个工厂对象决定创建出哪一种产品类的实例

属于创建型模式，但它不属于GOF23种设计模式

适用场景

工厂类负责创建的对象较少
客户端只需要传入工厂类的参数，对于如何创建对象的逻辑不需要关心

优点

只需要传入一个正确的参数，就可以获取你所需要的对象，无须知道其创建的细节

缺点

• 工厂类的职责相对过重，增加新的产品时需要修改工厂类的判断逻辑，违背开闭原则

• 不易于扩展过于复杂的产品结构

类图

相关代码

ICourse.java

package simpleFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/14
 * Time: 23:26
 * Description: 课程接口类
 */
public interface ICourse {
    
    
    /**
     * 录制视频
     */
    void record();
}

JavaCourse.java

package simpleFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/14
 * Time: 23:27
 * Description: No Description
 */
public class JavaCourse implements ICourse {
    
    
    public void record() {
    
    
        System.out.println("录制Java课程");
    }
}

PythonCourse.java

package simpleFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/14
 * Time: 23:29
 * Description: No Description
 */
public class PythonCourse implements ICourse{
    
    
    public void record() {
    
    
        System.out.println("录制Python课程");
    }
}

CourseFactory.java

package simpleFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/14
 * Time: 23:31
 * Description: No Description
 */
public class CourseFactory {
    
    
    public ICourse create(Class<? extends ICourse> clazz) {
    
    
        try {
    
    
            if (null != clazz) {
    
    
                return clazz.newInstance();
            }
        } catch (IllegalAccessException e) {
    
    
            e.printStackTrace();
        } catch (InstantiationException e) {
    
    
            e.printStackTrace();
        }
        return null;
    }
}

SimpleFactoryMain.java

package simpleFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/14
 * Time: 23:30
 * Description: No Description
 */
public class SimpleFactoryMain {
    
    
    public static void main(String[] args) {
    
    
        CourseFactory factory = new CourseFactory();
        ICourse javaCourse = factory.create(JavaCourse.class);
        javaCourse.record();
        ICourse pythonCourse = factory.create(PythonCourse.class);
        pythonCourse.record();
    }
}

工厂方法模式

定义

工厂方法模式（Factory Method Pattern）是指定义一个创建对象的接口，但实现这个接口的类来决定实例化哪个类，工厂方法让类的实例化推迟到子类中进行

属于创造型设计模式

适用场景

• 创建对象需要大量重复的代码
• 客户端（应用层）不依赖于产品类实例如何被创建、实现等细节
• 一个类通过其子类来指定创建哪个对象

优点

• 用户只需关心所需产品对应的工厂，无须关心创建细节

• 加入新产品不符合开闭原则，提高了系统的可扩展性

缺点

• 类的个数容易过多，增加了代码结构的复杂度
• 增加了系统的抽象性和理解难度

类图

相关代码

IPay.java

package task;

public interface IPay {
    
    
    void pay();
}

IIPayOut.java

package task;

public interface IIPayOut extends IPay {
    
    
}

IIPayIn.java

package task;

public interface IIPayIn extends IPay {
    
    
}

OtherIPay.java

package task;

public class OtherIPay implements IIPayOut {
    
    

    public void pay() {
    
    
        System.out.println("其他国外支付");
    }
}

AppleIPay.java

package task;

public class AppleIPay implements IIPayOut {
    
    
    public void pay() {
    
    
        System.out.println("苹果支付");
    }
}

WeIPay.java

package task;

public class WeIPay implements IIPayIn {
    
    
    public void pay() {
    
    
        System.out.println("微信支付");
    }
}

UniIPay.java

package task;

public class UniIPay implements IIPayIn {
    
    
    public void pay() {
    
    
        System.out.println("银联支付");
    }
}

AliIPay.java

package task;

public class AliIPay implements IIPayIn {
    
    
    public void pay() {
    
    
        System.out.println("支付宝支付！");
    }
}

IPayFactory.java

package task;

public interface IPayFactory {
    
    
    IPay create();
}

IPayOutFactory.java

package task;

public interface IPayOutFactory extends IPayFactory{
    
    
}

IPayInFactory.java

package task;

public interface IPayInFactory extends IPayFactory{
    
    
}

OtherPayFactory.java

package task;

public class OtherPayFactory implements IPayOutFactory{
    
    
    public IIPayOut create() {
    
    
        return new OtherIPay();
    }
}

ApplePayFactory.java

package task;

public class ApplePayFactory implements IPayOutFactory{
    
    
    public IIPayOut create() {
    
    
        return new AppleIPay();
    }
}

WePayFactory.java

package task;

public class WePayFactory implements IPayInFactory{
    
    
    public IIPayIn create() {
    
    
        return new WeIPay();
    }
}

AliPayFactory.java

package task;

public class AliPayFactory implements IPayInFactory{
    
    
    public IIPayIn create() {
    
    
        return new AliIPay();
    }
}

UniPayFactory.java

package task;

public class UniPayFactory implements IPayInFactory{
    
    
    public IIPayIn create() {
    
    
        return new UniIPay();
    }
}

TaskMain.java

package task;

public class TaskMain {
    
    
    public static void main(String[] args) {
    
    
        IPayInFactory factoryIn = new AliPayFactory();
        IPay payIn = factoryIn.create();
        payIn.pay();

        IPayOutFactory factoryOut = new ApplePayFactory();
        IPay payOut = factoryOut.create();
        payOut.pay();
    }
}

抽象工厂模式

定义

抽象工厂模式（Abastract Factory Pattern）是指提供一个创建一系列相关或相互依赖对象的接口，无须指定他们具体的类

属于创建型设计模式

适用场景

• 客户端（应用层）不依赖于产品类实例如何被创建、实现等细节
• 强调一系列相关的产品对象（属于同一产品族）一起使用创建对象需要大量重复的代码
• 提供一个产品类的库，所有的产品以同样的接口出现，从而使客户端不依赖于具体实现

优点

• 具体产品在应用层代码隔离，无须关心创建细节
• 将一个系列的产品族统一到一起创建

缺点

• 规定了所有可能被创建的产品集合，产品族中扩展新的产品困难，需要修改抽象工厂的接口
• 增加了系统的抽象性和理解难度

类图

相关代码

IVideo.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:13
 * Description: No Description
 */
public interface IVideo {
    
    
    void record();
}

JavaVideo.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:27
 * Description: No Description
 */
public class JavaVideo implements IVideo{
    
    
    @Override
    public void record() {
    
    
        System.out.println("录制Java视频");
    }
}

PythonVideo.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:28
 * Description: No Description
 */
public class PythonVideo implements IVideo{
    
    
    @Override
    public void record() {
    
    
        System.out.println("录制python视频");
    }
}

INote.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:12
 * Description: No Description
 */
public interface INote {
    
    
    void edit();
}

JavaNote.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:14
 * Description: No Description
 */
public class JavaNote implements INote {
    
    

    @Override
    public void edit() {
    
    
        System.out.println("记录Java笔记");
    }
}

PythonNote.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:26
 * Description: No Description
 */
public class PythonNote implements INote {
    
    

    @Override
    public void edit() {
    
    
        System.out.println("记录python笔记");
    }
}

CourseFactory.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 14:29
 * Description: No Description
 */
public abstract class CourseFactory {
    
    

    public void init(){
    
    
        System.out.println("初始化");
    }

    protected abstract INote createNote();

    protected abstract IVideo createVideo();
}

JavaCourseFactory.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 15:21
 * Description: No Description
 */
public class JavaCourseFactory extends CourseFactory {
    
    

    public INote createNote() {
    
    
        super.init();
        return new JavaNote();
    }

    public IVideo createVideo() {
    
    
        super.init();
        return new JavaVideo();
    }
}

PythonCourseFactory.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 15:21
 * Description: No Description
 */
public class PythonCourseFactory extends CourseFactory {
    
    

    public INote createNote() {
    
    
        super.init();
        return new PythonNote();
    }


    public IVideo createVideo() {
    
    
        super.init();
        return new PythonVideo();
    }
}

AbstractFactoryMain.java

package abstractFactory;

/**
 * Created with IntelliJ IDEA.
 * User: 轩辕龙儿
 * Date: 2021/3/17
 * Time: 15:22
 * Description: No Description
 */
public class AbstractFactoryMain {
    
    
    public static void main(String[] args) {
    
    

        JavaCourseFactory factory = new JavaCourseFactory();
        factory.createNote().edit();
        factory.createVideo().record();

    }
}