建造者模式(Builder Pattern)

模式定义

造者模式(Builder Pattern)：将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

UML类图

• Builder：抽象建造者
• ConcreteBuilder：具体建造者
• Director：指挥者

• Product：产品角色

  代码结构

  public static class BuilderApp
  {
      public static void Run()
      {
          Director director = new Director();
  
          Builder b1 = new ConcreteBuilder1();
          Builder b2 = new ConcreteBuilder2();
  
          director.Construct(b1);
          Product p1 = b1.GetResult();
          p1.Show();
  
          director.Construct(b2);
          Product p2 = b2.GetResult();
          p2.Show();
      }
  }
  
  public class Product
  {
      private List<string> _parts = new List<string>();
  
      public void Add(string part)
      {
          _parts.Add(part);
      }
  
      public void Show()
      {
          Console.WriteLine("\n Product Parts -----");
  
          foreach (string part in _parts)
          {
              Console.WriteLine(part);
          }
      }
  }
  
  public abstract class Builder
  {
      public abstract void BuildPartA();
      public abstract void BuildPartB();
      public abstract Product GetResult();
  }
  
  public class ConcreteBuilder1 : Builder
  {
      private Product _product = new Product();
      public override void BuildPartA()
      {
          _product.Add("PartA");
      }
  
      public override void BuildPartB()
      {
          _product.Add("PartB");
      }
  
      public override Product GetResult()
      {
          return _product;
      }
  }
  
  public class ConcreteBuilder2 : Builder
  {
      private Product _product = new Product();
      public override void BuildPartA()
      {
          _product.Add("PartX");
      }
  
      public override void BuildPartB()
      {
          _product.Add("PartY");
      }
  
      public override Product GetResult()
      {
          return _product;
      }
  }
  
  public class Director
  {
      public void Construct(Builder builder)
      {
          builder.BuildPartA();
          builder.BuildPartB();
      }
  }

  情景模式

  本次再拿麦当劳举例（不过我是比较喜欢吃中餐的）。麦当劳中的经典套餐有：鸡腿套餐、巨无霸套餐。套餐做为产品（Product）有汉堡、小食、饮品组成，厨师为具体建造者（ConcreteBuilder），顾客为指挥者（Director）。

  public static class BuilderRealWorldApp
  {
      public static void Run()
      {
          Customer customer = new Customer();
  
          Cook b1 = new ChickenPackageCook();
          Cook b2 = new BigMacCook();
  
          customer.Construct(b1);
          Package p1 = b1.GetResult();
          p1.Show();
  
          customer.Construct(b2);
          Package p2 = b2.GetResult();
          p2.Show();
      }
  }
  
  public class Package
  {
      private string _name = string.Empty;
      private List<string> _parts = new List<string>();
  
      public void Add(string part)
      {
          _parts.Add(part);
      }
  
      public Package(string name)
      {
          _name = name;
      }
  
      public void Show()
      {
          Console.WriteLine("\n {0} Parts is as below: -----",_name);
  
          foreach (string part in _parts)
          {
              Console.WriteLine(part);
          }
      }
  }
  
  public abstract class Cook
  {
      public abstract void Burger();
      public abstract void Snack();
      public abstract void Drink();
      public abstract Package GetResult();
  }
  
  public class ChickenPackageCook : Cook
  {
      private Package _product = new Package("Chicken Package");
      public override void Burger()
      {
          _product.Add("Chicken Burger");
      }
  
      public override void Snack()
      {
          _product.Add("French fries");
      }
      public override void Drink()
      {
          _product.Add("Milk");
      }
  
      public override Package GetResult()
      {
          return _product;
      }
  
  
  }
  
  public class BigMacCook : Cook
  {
      private Package _product = new Package("Big Mac Package");
      public override void Burger()
      {
          _product.Add("Big Mac Burger");
      }
  
      public override void Snack()
      {
          _product.Add("Vegetables");
      }
      public override void Drink()
      {
          _product.Add("Cola");
      }
  
      public override Package GetResult()
      {
          return _product;
      }
  }
  
  public class Customer
  {
      public void Construct(Cook builder)
      {
          builder.Burger();
          builder.Snack();
          builder.Drink();
      }
  }