Factory mode (factory pattern) detailed

Factory method Pattern: Defines an interface for creating objects, but subclasses decide which class to instantiate. The factory method lets classes defer instantiation to subclasses.

Including:

The Creator parent class (creator), which contains methods for creating objects (instead of new specific objects, creating different objects through parameters), and some basic methods;

The concrete creator (concrete creator), inherits the creator parent class, implements the method of creating the object, and different parameters can create different objects;

The Product class parent (product), which contains the basic use method of the product, is used by the basic method of the Creator parent class (creator);

The specific product (concrete creator), inherits the product class parent class, customizes the specific product for the specific creator (concrete creator) to create;

Specific methods:

1. The Product class is the parent class (product), which contains some basic methods of the product.

Code:

/** * @time May 26, 2014 * * * Package factory;  
      
Import java.util.ArrayList;  
    /** * @author C.l.wang */Public abstract class Pizza {String name; String Dough; Raw dough String sauce; Sauce arraylist<string> toppings = new arraylist<string> ();  
        decorated void Prepare () {SYSTEM.OUT.PRINTLN ("preparing" + name);  
        System.out.println ("tossing dough ..." + dough);  
        System.out.println ("adding sauce ..." + sauce);  
        SYSTEM.OUT.PRINTLN ("Adding toppings:");  
        for (int i=0; i<toppings.size (); ++i) {System.out.println ("" + toppings.get (i));  
    } void Bake () {System.out.println ("Bake for minutes at 350");  
    void Cut () {System.out.println ("cutting the pizza into diagonal slices"); } void Box () {System.out.println ("place Pizza in official PizzastorE box ");  
    Public String GetName () {return name; }  
}

2. Specific product categories (concrete product), specific product customization methods.

Code:

/** * @time May 26, 2014 */package factory;  
        /** * @author C.l.wang * */public class Nystylecheesepizza extends Pizza {public Nystylecheesepizza () {  
        Name = "NY Style sauce and Cheese Pizza";  
        Dough = "Thin crust dough";  
              
        sauce = "marinara sauce";  
    Toppings.add ("grated Reggiano Cheese");  
      
}/** * @time May 26, 2014 * * * Package factory; /** * @author C.l.wang * */public class Chicagostylecheesepizza extends Pizza {public Chicagostylecheesepizz  
        A () {name = "Chicago Style Deep Dish Cheese Pizza";  
        Dough = "Extra thick crust dough";  
              
        sauce = "plum tomato sauce";  
    Toppings.add ("shredded mozzarella Cheese");  
    } void Cut () {System.out.println ("cutting the pizza into square slices"); }  
}

3. Creator parent Class (creator), the specific use method, the method that invokes the Product class parent (product), provides a different specific product class (concrete product) based on the parameters.

Code:

/** 
 * @time May 26, 2014 * * *
package factory;  
      
/** 
 * @author C.l.wang 
 * 
 *
/Public abstract class Pizzastore {public  
    Pizza Orderpizza (String Item) {  
        Pizza Pizza;  
        Pizza = Createpizza (item);  
              
        Pizza.prepare ();  
        Pizza.bake ();  
        Pizza.cut ();  
        Pizza.box ();  
              
        return pizza;  
    }  
          
    Abstract Pizza Createpizza (String item);  

4. Specific creator (concrete creator), creating different specific products (concrete product) through parameters.

Code:

/** * @time May 26, 2014 * * * Package factory; /** * @author C.l.wang * */public class Nypizzastore extends Pizzastore {/* (non-javadoc) * @se E factory.  Pizzastore#createpizza (java.lang.String) */@Override Pizza Createpizza (String Item) {//TODO auto-generated method Stub if (item.equals ("cheese")) {return new Nystylecheesepi  
        Zza ();  
    else return null;  
      
}/** * @time May 26, 2014 * * * Package factory; 
     /** * @author C.l.wang * */public class Chicagopizzastore extends Pizzastore {* * (Non-javadoc) * @see Factory. Pizzastore#createpizza (java.lang.String) */@Override Pizza Createpizza (String Item) {//TODO Aut o-generated method Stub if (item.equals ("cheese")) {return new CHICAGOSTYLECHEESEP  
        Izza ();  
    else return null;  
      }
} 

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5. Test, create a different specific creator (concrete creator), that is, the factory, by calling the function parameters, select a different product to use.

Code:

/** 
 * @time May 26, 2014 * * *
package factory;  
      
/** 
 * @author C.l.wang * */Public
class Pizzatestdrive {  
      
    /** 
     * @param 
     args
    * * public static void Main (string[] args) {  
        //TODO auto-generated method stub  
        Pizzastore nystore = new Nypizzastor E ();  
        Pizzastore Chicagostore = new Chicagopizzastore ();  
              
        Pizza Pizza = Nystore.orderpizza ("cheese");  
        System.out.println ("Ethan ordered a" + pizza.getname () + "\ n");  
              
        Pizza = Chicagostore.orderpizza ("cheese");  
        System.out.println ("Joel ordered a" + pizza.getname () + "\ n");  
    }  
      

6. Output:

Preparing NY Style sauce and Cheese Pizza  
tossing dough ... Thin crust dough  
adding sauce ... Marinara sauce  
Adding toppings: grated reggiano Cheese bake for "minutes at" cutting the  
pizza into  
D iagonal slices Place  
pizza in official Pizzastore box  
Ethan ordered a NY Style sauce and Cheese pizza  
      
G Chicago Style Deep Dish Cheese Pizza tossing  
... Extra Thick crust dough  
adding sauce ... Plum tomato sauce  
adding toppings: shredded mozzarella Cheese bake for "minutes at" cutting the  
p Izza into the square slices place  
pizza in official Pizzastore box  
Joel ordered a Chicago Style Deep Dish Cheese Za

Object-Oriented design principles:

Dependency inversion principle: to rely on abstraction, do not rely on specific classes.

Guiding principles:

1. A variable cannot hold a reference to a specific class.

2. Do not allow classes to derive from specific classes.

3. Do not overwrite methods that have been implemented in the base class.