【设计模式_4】FactoryMethod工厂方法

梦里梦外; 2022-10-06 10:00 138阅读 0赞

## 一、简介 ##

以Template模板方法架构获取产生对象实例的工厂就是Factory Method Pattern。  
父类：规定对象的创建方法，但不深入到较为具体的类名；  
子类：所有具体的完整内容都放子类。

## 二、示例 ##

建立一个生产身份证的工厂

<table> 
 <thead> 
  <tr> 
   <th>类名</th> 
   <th>包名</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>Product</td> 
   <td>framework</td> 
   <td>抽象类-定义抽象方法use()</td> 
  </tr> 
  <tr> 
   <td>Factory</td> 
   <td>framework</td> 
   <td>抽象类-实现方法create</td> 
  </tr> 
  <tr> 
   <td>IDCard</td> 
   <td>idcard</td> 
   <td>抽象类-实现方法use()</td> 
  </tr> 
  <tr> 
   <td>IDCardFactory</td> 
   <td>idcard</td> 
   <td>普通类-实现方法createProduct、engineerProduct</td> 
  </tr> 
 </tbody> 
</table>

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FkaWRhczc0ODkxNDk2_size_16_color_FFFFFF_t_70]  
**Factory抽象工厂**

package FactoryMethod.framework;
    
    public abstract class Factory { 
        public final Product create(String owner){ 
            Product p = createProduct(owner);
            registerProduct(p);
            return p;
        }
        protected abstract Product createProduct(String owner);
        protected abstract void registerProduct(Product product);
    }

**IDCardFactory**

package FactoryMethod.idcard;
    
    import FactoryMethod.framework.Factory;
    import FactoryMethod.framework.Product;
    
    import java.util.Vector;
    
    public class IDCardFactory extends Factory { 
        private Vector owners = new Vector();
    
        @Override
        protected Product createProduct(String owner) { 
            return new IDCard(owner);
        }
    
        @Override
        protected void registerProduct(Product product) { 
            owners.add(((IDCard)product).getOwner());
        }
        public Vector getOwners(){ 
            return owners;
        }
    }

**Product**

package FactoryMethod.framework;
    
    public abstract class Product { 
        public abstract void use();
    }

**IDCard**

package FactoryMethod.idcard;
    
    import FactoryMethod.framework.Product;
    
    public class IDCard extends Product { 
        private String owner;
        public IDCard(String owner){ 
            System.out.println("ConstructIDCard:"+owner);
            this.owner = owner;
        }
        @Override
        public void use() { 
            System.out.println("UseIDCard:"+owner);
        }
        public String getOwner(){ 
            return owner;
        }
    }

**TestFactoryMethod**

package FactoryMethod.idcard;
    
    import FactoryMethod.framework.Factory;
    import FactoryMethod.framework.Product;
    
    public class TestFactoryMethod { 
        public static void main(String[] args) { 
            Factory factory = new IDCardFactory();
            Product card1 = factory.create("001");
            Product card2 = factory.create("002");
            Product card3 = factory.create("003");
            card1.use();
            card2.use();
            card3.use();
        }
    }

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