C#说明设计模式（三）生成器模式

创建型的设计模式：(builder 生成器模式)
Definition (定义)
  Separate the construction of a complex object from its representation so that the same construction process can create different representations.
（将一个复合对象的的结构和对象的呈现分开，这样，相同的结构可以生成不同的显示）

说明：
Builder (VehicleBuilder) 指定生成器接口为了建立产品对象的各个部分。
specifies an abstract interface for creating parts of a product object
ConcreteBuilder (MotorCycleBuilder , CarBuilder)架构和聚集产品的各个部分用于完成生成器的接口
.constructs and assembles parts of the product by implementing the Builder interface
Director ( Shop ) 建立对象用生成器接口
.constructs an object using the Builder interface
Product ( Vehicle ) 在结构下呈现对象。生成器生成产品内部呈现方式，并且定义了执行过程通过它的组合
实例：
在一个商店(Shop)里,管理员决定了商品的呈现方式用一种固定的风格.进来商店的商品(Product)让营销员(Director)按照规格生成(Builder)摆放每个具体的商品摆放地址。

原文:
Participants

The classes and/or objects participating in this pattern are: Builder  (VehicleBuilder) specifies an abstract interface for creating parts of a Product object ConcreteBuilder  (MotorCycleBuilder, CarBuilder, ScooterBuilder) constructs and assembles parts of the product by implementing the Builder interface defines and keeps track of the representation it creates provides an interface for retrieving the product Director  (Shop) constructs an object using the Builder interface Product  (Vehicle) represents the complex object under construction. ConcreteBuilder builds the product's internal representation and defines the process by which it's assembled includes classes that define the constituent parts, including interfaces for assembling the parts into the final result

UML代码:

using System;
using System.Collections;

// "Director"

class Director
{
  // Methods
  public void Construct( Builder builder )
  {
    builder.BuildPartA();
    builder.BuildPartB();
  }
}

// "Builder"

abstract class Builder
{
  // Methods
  abstract public void BuildPartA();
  abstract public void BuildPartB();
  abstract public Product GetResult();
}

// "ConcreteBuilder1"

class ConcreteBuilder1 : Builder
{
  // Fields
  private Product product;

  // Methods
  override public void BuildPartA()
  {
    product = new Product();
    product.Add( "PartA" );
  }

  override public void BuildPartB()
  {
    product.Add( "PartB" );
  }

  override public Product GetResult()
  {
    return product;
  }
}

// "ConcreteBuilder2"

class ConcreteBuilder2 : Builder
{
  // Fields
  private Product product;

  // Methods
  override public void BuildPartA()
  {
    product = new Product();
    product.Add( "PartX" );
  }

  override public void BuildPartB()
  {
    product.Add( "PartY" );
  }

  override public Product GetResult()
  {
    return product;
  }
}

// "Product"

class Product
{
  // Fields
  ArrayList parts = new ArrayList();
 
  // Methods
  public void Add( string part )
  {
    parts.Add( part );
  }

  public void Show()
  {
    Console.WriteLine( "\nProduct Parts -------" );
    foreach( string part in parts )
      Console.WriteLine( part );
  }
}
/// <summary>
/// Client test
/// </summary>
public class Client
{
  public static void Main( string[] args )
  {
    // Create director and builders
    Director director = new Director( );

    Builder b1 = new ConcreteBuilder1();
    Builder b2 = new ConcreteBuilder2();

    // Construct two products
    director.Construct( b1 );
    Product p1 = b1.GetResult();
    p1.Show();

    director.Construct( b2 );
    Product p2 = b2.GetResult();
    p2.Show();
  }
}

RealWorld代码


using System;
using System.Collections;

// "Director"

class Shop
{
  // Methods
  public void Construct( VehicleBuilder vehicleBuilder )
  {
    vehicleBuilder.BuildFrame();
    vehicleBuilder.BuildEngine();
    vehicleBuilder.BuildWheels();
    vehicleBuilder.BuildDoors();
  }
}

// "Builder"

abstract class VehicleBuilder
{
  // Fields
  protected Vehicle vehicle;

  // Properties
  public Vehicle Vehicle
  {
    get{ return vehicle; }
  }

  // Methods
  abstract public void BuildFrame();
  abstract public void BuildEngine();
  abstract public void BuildWheels();
  abstract public void BuildDoors();
}

// "ConcreteBuilder1"

class MotorCycleBuilder : VehicleBuilder
{
  // Methods
  override public void BuildFrame()
  {
    vehicle = new Vehicle( "MotorCycle" );
    vehicle[ "frame" ] = "MotorCycle Frame";
  }

  override public void BuildEngine()
  {
    vehicle[ "engine" ] = "500 cc";
  }

  override public void BuildWheels()
  {
    vehicle[ "wheels" ] = "2";
  }

  override public void BuildDoors()
  {
    vehicle[ "doors" ] = "0";
  }
}

// "ConcreteBuilder2"

class CarBuilder : VehicleBuilder
{
  // Methods
  override public void BuildFrame()
  {
    vehicle = new Vehicle( "Car" );
    vehicle[ "frame" ] = "Car Frame";
  }

  override public void BuildEngine()
  {
    vehicle[ "engine" ] = "2500 cc";
  }

  override public void BuildWheels()
  {
    vehicle[ "wheels" ] = "4";
  }

  override public void BuildDoors()
  {
    vehicle[ "doors" ] = "4";
  }
}

// "ConcreteBuilder3"

class ScooterBuilder : VehicleBuilder
{
  // Methods
  override public void BuildFrame()
  {
    vehicle = new Vehicle( "Scooter" );
    vehicle[ "frame" ] = "Scooter Frame";
  }

  override public void BuildEngine()
  {
    vehicle[ "engine" ] = "none";
  }

  override public void BuildWheels()
  {
    vehicle[ "wheels" ] = "2";
  }

  override public void BuildDoors()
  {
    vehicle[ "doors" ] = "0";
  }
}

// "Product"

class Vehicle
{
  // Fields
  private string type;
  private Hashtable parts = new Hashtable();

  // Constructors
  public Vehicle( string type )
  {
    this.type = type;
  }

  // Indexers
  public object this[ string key ]
  {
    get{ return parts[ key ]; }
    set{ parts[ key ] = value; }
  }

  // Methods
  public void Show()
  {
    Console.WriteLine( "\n---------------------------");
    Console.WriteLine( "Vehicle Type: "+ type );
    Console.WriteLine( " Frame : " + parts[ "frame" ] );
    Console.WriteLine( " Engine : "+ parts[ "engine"] );
    Console.WriteLine( " #Wheels: "+ parts[ "wheels"] );
    Console.WriteLine( " #Doors : "+ parts[ "doors" ] );
  }
}

/// <summary>
/// BuilderApp test
/// </summary>
public class BuilderApp
{
  public static void Main( string[] args )
  {
    // Create shop and vehicle builders
    Shop shop = new Shop();
    VehicleBuilder b1 = new ScooterBuilder();
    VehicleBuilder b2 = new CarBuilder();
    VehicleBuilder b3 = new MotorCycleBuilder();

    // Construct and display vehicles
    shop.Construct( b1 );
    b1.Vehicle.Show();

    shop.Construct( b2 );
    b2.Vehicle.Show();

    shop.Construct( b3 );
    b3.Vehicle.Show();
  }
}