Design Patterns study notes (b) - creator of the model (Creational Pattern)

Creator mode (Creational Pattern)

1. Simple factory pattern (Simple Factory)
   • Also known as static factory method pattern, it does not belong to one of 23 kinds of GOF design patterns

   Factory.creteObject(objectName);

2. Factory method model (plant model) (Factory Method)
   • A class does not know it needs an object of class: the client does not need to know the class name specific product category, you only need to know the corresponding plant
   • A class to specify which objects created by its subclasses
   • The delegate tasks to create objects of multiple plants in one sub-category, sub-category and then dynamically assigned as needed

   FactoryA.creteObject(); 
   FactoryB.creteObject(); 

3. Abstract factory mode (Mode Kit) (Abstract Factory)
   • Creating a series of related or dependent object's interface, without specifying their concrete classes
     (factory pattern generating only one object, abstract factory model generates a set of related objects)
   • When each of the abstract factory model class concrete factory creates only a target product, i.e. there is only one knot grade product, abstract factory model degenerates into the factory method pattern;
     
   • When the factory method abstract factory pattern combined with the plant-specific, providing a unified product factory to create objects and create objects as static factory method design methods, the factory method pattern degenerate into a simple factory pattern

   interface PcFactory{
       Mouse createMouse();
       Keyboard createKeyboard();
   }
   class HpFactory implements PcFactory{
       Mouse createMouse() return HpMouse();
       Keyboard createKeyboard() return HpKeyboard();
   }
   class DellFactory implements PcFactory{
       Mouse createMouse() return DellMouse();
       Keyboard createKeyboard() return DellKeyboard();
   }

4. Builder mode (generating mode) (Builder)
   • It represents the construct and its separation of a complex object, such that the same build process can create different representations
   • The construction and performance of complex objects separated from the object, so that the same construction process can create different representations

   //包含四个角色：
   //Builder：抽象建造者；ConcreteBuilder：具体建造者；
   //Director：指挥者；Product：产品角色
   ConcreteBuilder builder = new ConcreteBuilder();
   Director  director = new Director();
   director.setBuilder(builder);
   Product pd =  director.constuct();
   pd.show();

5. Prototype model (Prototype)
   • Definition: Use prototype instance of the specified object type to create, create new objects by copying this example
   • Application: Java using serialization and deserialization stream to achieve a deep clone
6. Singleton pattern (the Singleton)
   • Responsibilities singleton class too heavy, contrary to the "principle of the single function" to some extent.
     Because both as a singleton class factory role, provides factory methods, but also serves as a product role, contains a number of business methods, the product features and product creation itself fused together