创建型模式：Builder（生成器）-优快云博客

本文深入探讨了构建模式这一软件设计模式的核心概念，它通过抽象对象构造步骤来实现不同实现方式构建不同对象的表现形式。具体展示了如何在产品（如披萨）的构建过程中运用构建者模式，并通过实例介绍了抽象接口、具体构建者和导演角色的职责。

The builder pattern is an object creation software design pattern. The intention is to abstract steps of construction of objects so that different implementations of these steps can construct different representations of objects. Often, the builder pattern is used to build products in accordance with the composite pattern.

Builder
Abstract interface for creating objects (product).
Concrete Builder
Provides implementation for Builder. It is an object able to construct other objects. Constructs and assembles parts to build the objects.

/** "Product" */
 class Pizza {
   private String dough = "";
   private String sauce = "";
   private String topping = "";
 
   public void setDough (String dough)     { this.dough = dough; }
   public void setSauce (String sauce)     { this.sauce = sauce; }
   public void setTopping (String topping) { this.topping = topping; }
 }
 
 
 /** "Abstract Builder" */
 abstract class PizzaBuilder {
   protected Pizza pizza;
 
   public Pizza getPizza() { return pizza; }
   public void createNewPizzaProduct() { pizza = new Pizza(); }
 
   public abstract void buildDough();
   public abstract void buildSauce();
   public abstract void buildTopping();
 }
 
 /** "ConcreteBuilder" */
 class HawaiianPizzaBuilder extends PizzaBuilder {
   public void buildDough()   { pizza.setDough("cross"); }
   public void buildSauce()   { pizza.setSauce("mild"); }
   public void buildTopping() { pizza.setTopping("ham+pineapple"); }
 }
 
 /** "ConcreteBuilder" */
 class SpicyPizzaBuilder extends PizzaBuilder {
   public void buildDough()   { pizza.setDough("pan baked"); }
   public void buildSauce()   { pizza.setSauce("hot"); }
   public void buildTopping() { pizza.setTopping("pepperoni+salami"); }
 }
 
 
 ''/** "Director" */''
 class Waiter {
   private PizzaBuilder pizzaBuilder;
 
   public void setPizzaBuilder (PizzaBuilder pb) { pizzaBuilder = pb; }
   public Pizza getPizza() { return pizzaBuilder.getPizza(); }
 
   public void constructPizza() {
     pizzaBuilder.createNewPizzaProduct();
     pizzaBuilder.buildDough();
     pizzaBuilder.buildSauce();
     pizzaBuilder.buildTopping();
   }
 }
 
 /** A customer ordering a pizza. */
 class BuilderExample {
   public static void main(String[] args) {
     Waiter waiter = new Waiter();
     PizzaBuilder hawaiian_pizzabuilder = new HawaiianPizzaBuilder();
     PizzaBuilder spicy_pizzabuilder = new SpicyPizzaBuilder();
 
     waiter.setPizzaBuilder ( hawaiian_pizzabuilder );
     waiter.constructPizza();
 
     Pizza pizza = waiter.getPizza();
   }
 }