Java Design Patterns--creating patterns--factory methods

Factory method Definition:

　　

1 Factory Method2 3 Overview4 defines an interface for creating objects, letting subclasses decide which class to instantiate. FactoryMethod defers the instantiation of a class to its subclasses. 5 6 Applicability7     1. When a class does not know the class of the object it must create. 8 9     2when a class wants to specify the object it creates by its subclasses. Ten  One     3when a class delegates the responsibility of creating an object to one of several helper subclasses, and you want to set which helper subclass is the agent this information is localized.  A participants -     1. Product - an interface that defines the objects created by the factory method.  the  -     2. Concreteproduct - implement the Product interface.  -  +     3. Creator - declares a factory method that returns an object of type product.  + Creator can also define a default implementation of a factory method that returns a default Concreteproduct object.  A You can call the factory method to create a product object.  at  -     4. Concretecreator -Redefine the factory method to return a concreteproduct instance.

Test code:

1  Public classTest {2 3      Public Static voidMain (string[] args) {4Iworkfactory studentworkfactory =Newstudentworkfactory ();5 studentworkfactory.getwork (). DoWork ();6         7Iworkfactory teacherworkfactory =Newteacherworkfactory ();8 teacherworkfactory.getwork (). DoWork ();9     }Ten  One}

1  Public Interface iworkfactory {23work    getwork (); 4 }

 1  public  interface   work { 2   void   DoWork ();  4 } 

 1  public  class  Studentworkfactory implements   Iworkfactory {      2  3  public   work getwork () { 4  return  new   Studentwork ();  5   6  7 } 

1  Public class Implements Work {23      Public void doWork () {4         SYSTEM.OUT.PRINTLN ("Students do homework!") ); 5     }67 }

1  Public class Implements iworkfactory {23      Public Work Getwork () {4         return New teacherwork (); 5     }67 }

1  Public class Implements Work {23      Public void doWork () {4         System.out.println ("The teacher approves the work!") ); 5     }67 }

Java Design Patterns--creating patterns--factory methods