Design Mode: java

Design Mode: java

I. Creation Mode

Mode name	Definition	Usage Frequency	Learning Difficulty
Simple factory Mode (Simple Factory Pattern)	Defines a factory class. It can return instances of different classes according to different parameters. The created instances usually share the same parent class.	★★☆☆☆	★★★☆☆
Factory method mode (Factory Method Pattern)	Define an interface for creating objects, but let the subclass decide which class to instantiate. The factory method mode delays the instantiation of a class to its subclass.	★★☆☆☆	★★★★★
Abstract Factory Model (Abstract Factory Pattern)	Provides an interface for creating a series of related or mutually dependent objects without specifying their specific classes.	★★★★☆	★★★★★
Builder Mode (Builder Pattern)	Separates the construction of a complex object from its representation, so that different representations can be created during the same construction process.	★★★★☆	★★☆☆☆
Prototype (Prototype Pattern)	Use the prototype instance to specify the type of the object to be created, and copy the prototype to create a new object.	★★★☆☆	★★★☆☆
Singleton Mode (Singleton Pattern)	Make sure that a class has only one instance and provides a global access point to access this unique instance.	★☆☆☆☆	★★★★☆

2. Structure and Implementation of the simple factory Model

(1) Structure of the simple factory Model

Customers who want to buy a milkshake pizza or a bacon pizza will use the factory to buy it. If this function is implemented first.

1) create a form first

2) Step 2: create a product parent class

// The product's parent class // The keyword used for the abstract method is abstract public abstract class Pizza {public abstract string say ();}

3) Step 3: Create a subclass of the milkshake pizza

Note: The parent class must be inherited.

Public class chees: Pizza {public override string say () {return "I'm a milkshake Pizza ";}}

4) Step 4: create a sub-class of bacon

Public class pg: Pizza {public override string say () {return "I'm a bacon Pizza ";}}

5) Step 5: Create a factory

// Abstract class factory public abstract class Fack {// static parent class public static Pizza st (string Type) {Pizza pizza = null; switch (Type) {case "milkshake Pizza ": pizza = new chees (); break; case "bacon pizza": pizza = new pg (); break; default: break;} return pizza ;}}

6) Click the order button of the main form to write the following code:

Private void btOk_Click (object sender, EventArgs e) {int num1 = Convert. toInt32 (txtLfet. text); string Signature = cb. text; int num2 = Convert. toInt32 (txtRight. text); // 04. call the static method of the Factory, input the type, and obtain the return value Operator part = Factory. cu (partial); part. numLeft = num1; part. numRight = num2; int result = 0; // 05. call the Calc () corresponding to the parent variable to complete the calculation and receive the return value try {result = part. calc ();} catch (Exception ex) {MessageBox. show (ex. message);} // 06. label1.Text = result is displayed in the Label. toString ();}

Iii. Singleton Mode