Builder Pattern Code Review

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Download Description:builder pattern download
.NET Framework:3.5
..NET Language:C#
Date Published:2009-07-01
Download Size:9 KB

Define the Pattern Interface and Handler Objects

Define the IProductBuilder interface to be used as the "blueprint" for the main Builder classes.

interface IProductBuilder { FactoryProduct Product { get; }
void BuildFrame(); void BuildEngine(); void BuildWheels(); void BuildDoors(); }

This interface defines the methods required to construct a specific object.

The MotorCycleBuilder class (object) represents a Builder class.

class MotorCycleBuilder : IProductBuilder { public MotorCycleBuilder() { this.Product = new FactoryProduct("MotorCycle"); }
public FactoryProduct Product { get; private set; }
public void BuildFrame() { this.Product["frame"] = "MotorCycle Frame"; } public void BuildEngine() { this.Product["engine"] = "500 cc"; } public void BuildWheels() { this.Product["wheels"] = "2"; } public void BuildDoors() { this.Product["doors"] = "0"; } }

This class inherits from the IProductBuilder interface, and therefore implements the required methods to construct a MotorCycle object.

The VehicleBuilder class (object) represents a Builder class.

class VehicleBuilder : IProductBuilder { public VehicleBuilder() { this.Product = new FactoryProduct("Vehicle"); }
public FactoryProduct Product { get; private set; }
public void BuildFrame() { this.Product["frame"] = "Vehicle Frame"; } public void BuildEngine() { this.Product["engine"] = "2500 cc"; } public void BuildWheels() { this.Product["wheels"] = "4"; } public void BuildDoors() { this.Product["doors"] = "4"; } }

This class inherits from the IProductBuilder interface, and therefore implements the required methods to construct a Vehicle object.

The ScooterBuilder class (object) represents a Builder class.

class ScooterBuilder : IProductBuilder { public ScooterBuilder() { this.Product = new FactoryProduct("Scooter"); }
public FactoryProduct Product { get; private set; }
public void BuildFrame() { this.Product["frame"] = "Scooter Frame"; } public void BuildEngine() { this.Product["engine"] = "50 cc"; } public void BuildWheels() { this.Product["wheels"] = "2"; } public void BuildDoors() { this.Product["doors"] = "0"; } }

This class inherits from the IProductBuilder interface, and therefore implements the required methods to construct a Scooter object.

Define the Factory Director and Factory Product Objects

The FactoryDirector class (object) represents a Director class.

class FactoryDirector { public void Construct(IProductBuilder builder) { builder.BuildFrame(); builder.BuildEngine(); builder.BuildWheels(); builder.BuildDoors(); } }

This class invokes the methods associated with a specific Builder class to construct a particular object.

The FactoryProduct class (object) defines the details stored about a particular product.

class FactoryProduct { private StringDictionary parts = new StringDictionary(); private String productType = String.Empty;
public FactoryProduct(String type) { this.productType = type; }
public String this[String key] { get { return this.parts[key]; } set { this.parts[key] = value; } }
public void DisplayProduct() { Console.WriteLine("\n"); Console.WriteLine("Product Type: {0}", this.productType); Console.WriteLine("\tFrame: {0}", this.parts["frame"]); Console.WriteLine("\tEngine: {0}", this.parts["engine"]); Console.WriteLine("\tWheels: {0}", this.parts["wheels"]); Console.WriteLine("\tDoors: {0}", this.parts["doors"]); } }

Use the Builder Pattern

The Program class creates an instance of the FactoryDirector class, and creates instances of the different Builder classes.

class Program { static void Main(string[] args) { FactoryDirector director = new FactoryDirector();
ScooterBuilder sctBuilder = new ScooterBuilder(); VehicleBuilder vchBuilder = new VehicleBuilder(); MotorCycleBuilder mcyBuilder = new MotorCycleBuilder();
director.Construct(sctBuilder); sctBuilder.Product.DisplayProduct();
director.Construct(vchBuilder); vchBuilder.Product.DisplayProduct();
director.Construct(mcyBuilder); mcyBuilder.Product.DisplayProduct();
Console.Read(); } }

The Director class (object) constructs each builder object (product) and displays required output.