Java设计模式之工厂模式案例详解

工厂模式（Factory Pattern）是Java中最常用的设计模式之一。这种类型的设计模式属于创建型模式，它提供了一种创建对象的最佳方式。本文将通过案例详细讲解一下工厂模式，需要的可以参考一下

分类

1.简单工厂模式

2.工厂方法模式

3.抽象工厂模式

案例

需求

根据蛋糕的不同口味，分别创建苹果味和香蕉味的蛋糕实例

方案一:简单工厂模式

定义蛋糕父类

/** * 蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class Cake { }

定义苹果味的蛋糕

/** * 苹果蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class AppleCake extends Cake{ public AppleCake(){ System.out.println("创建了苹果蛋糕实例"); } }

定义香蕉味的蛋糕

/** * 香蕉蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class BananaCake extends Cake{ public BananaCake(){ System.out.println("创建了香蕉蛋糕实例"); } }

定义蛋糕工厂类

/** * 蛋糕工厂 * @author:liyajie * @createTime:2022/2/14 10:16 * @version:1.0 */ public class CakeFactory { public Cake createCake(String type){ if("apple".equals(type)){ return new AppleCake(); }else if("banana".equals(type)){ return new BananaCake(); }else { return null; } } }

定义测试类

/** * 测试类 * @author:liyajie * @createTime:2022/2/14 10:25 * @version:1.0 */ public class Test { public static void main(String[] args) { CakeFactory cakeFactory = new CakeFactory(); cakeFactory.createCake("apple"); cakeFactory.createCake("banana"); } }

查看结果：

方案二:工厂方法模式

定义蛋糕父类

/** * 蛋糕父类 * @author:liyajie * @createTime:2022/2/14 10:44 * @version:1.0 */ public abstract class Cake { }

定义苹果蛋糕

/** * 苹果蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class AppleCake extends Cake { public AppleCake(){ System.out.println("创建了苹果蛋糕实例"); } }

定义香蕉蛋糕

/** * 香蕉蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class BananaCake extends Cake { public BananaCake(){ System.out.println("创建了香蕉蛋糕实例"); } }

定义蛋糕工厂类该类主要是定义了createCake抽象方法，并且在无参构造函数中进行调用，具体的实现是在子类里进行实例化的

/** * 蛋糕工厂类 * @author:liyajie * @createTime:2022/2/14 11:55 * @version:1.0 */ public abstract class CakeFactory { abstract Cake createCake(); public CakeFactory() { createCake(); } }

定义苹果蛋糕工具类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 11:58 * @version:1.0 */ public class AppleCakeFactory extends CakeFactory{ @Override public Cake createCake() { return new AppleCake(); } }

定义香蕉蛋糕工具类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 11:58 * @version:1.0 */ public class BananaCakeFactory extends CakeFactory{ @Override public Cake createCake() { return new BananaCake(); } }

定义测试类

/** * 测试类 * @author:liyajie * @createTime:2022/2/14 12:02 * @version:1.0 */ public class Test { public static void main(String[] args) { AppleCakeFactory appleCakeFactory = new AppleCakeFactory(); BananaCakeFactory bananaCakeFactory = new BananaCakeFactory(); } }

查看结果

方案三:抽象工厂模式

定义蛋糕父类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 10:44 * @version:1.0 */ public abstract class Cake { }

定义苹果蛋糕

/** * 苹果蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class AppleCake extends Cake { public AppleCake(){ System.out.println("创建了苹果蛋糕实例"); } }

定义香蕉蛋糕

/** * 香蕉蛋糕 * @author:liyajie * @createTime:2022/2/14 10:17 * @version:1.0 */ public class BananaCake extends Cake { public BananaCake(){ System.out.println("创建了香蕉蛋糕实例"); } }

定义蛋糕工厂类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 11:55 * @version:1.0 */ public interface CakeFactory { Cake createCake(); }

定义苹果蛋糕工厂类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 11:58 * @version:1.0 */ public class AppleCakeFactory implements CakeFactory { @Override public Cake createCake() { return new AppleCake(); } }

定义香蕉蛋糕工厂类

/** * @desc: * @author:liyajie * @createTime:2022/2/14 11:58 * @version:1.0 */ public class BananaCakeFactory implements CakeFactory { @Override public Cake createCake() { return new BananaCake(); } }

定义蛋糕工厂生成器

/** * @desc: * @author:liyajie * @createTime:2022/2/14 17:46 * @version:1.0 */ public class FactoryProducter { CakeFactory cakeFactory; public FactoryProducter(CakeFactory cakeFactory){ setCakeFactory(cakeFactory); } public void setCakeFactory(CakeFactory cakeFactory){ this.cakeFactory = cakeFactory; cakeFactory.createCake(); } }

定义测试类

/** * 测试类 * @author:liyajie * @createTime:2022/2/14 12:02 * @version:1.0 */ public class Test { public static void main(String[] args) { new FactoryProducter(new AppleCakeFactory()); new FactoryProducter(new BananaCakeFactory()); } }

查看结果

对比分析

方案一：简单工厂模式，工厂类是只有一个，只需要改动这一个地方避免了业务逻辑的代码和创建对象的代码大量耦合，降低耦合让代码更加条理清晰，更加优雅
方案二：工厂方法模式是简单工厂模式的衍生，定义一个创建对象的抽象方法，由子类决定要实例化的类，将对象实例化延迟到子类，实现了可扩展，层次结构更复杂，可以应用到更复杂的场合
方案三：抽象工厂模式，定义一个接口来用于创建相关的或者具有依赖关系的对象簇，将实例化对象的细节提取出来，放到工厂角色，由工厂角色负责具体的创建细节，解耦合，提高项目可扩展性和可维护性