【1】基本概念
建造(Builder)模式是一种对象构建的设计模式，它可以将复杂对象的建造过程抽象出来（抽象类别），使这个抽象过程的不同实现方法可以构造出不同表现（属性）的对象。
【2】简单分析
我们先来看一下该设计模式的UML结构图
上图是Strategy 模式的结构图,让我们可以进行更方便的描述:
下面以一个简单的例子来展示该模式，先看下代码结构图：
3.1 先创建一个Product类--产品类：
package com.andyidea.patterns.product; /** * Product--产品类 * @author Andy.Chen * */ public 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; } }3.2 创建抽象建造者类：PizzaBuilder.java
package com.andyidea.patterns.builder; import com.andyidea.patterns.product.Pizza; /** * Builder类--抽象建造者类 * @author Andy.Chen * */ public 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(); }3.3 创建具体建造者类
HawaiianPizzaBuilder.java源码：
package com.andyidea.patterns.concretebuilder; import com.andyidea.patterns.builder.PizzaBuilder; /** * ConcreteBuilder类--具体建造者类 * @author Andy.Chen * */ public class HawaiianPizzaBuilder extends PizzaBuilder { @Override public void buildDough() { System.out.println("Hawaiian-Dough"); pizza.setDough("Hawaiian-Dough"); } @Override public void buildSauce() { System.out.println("Hawaiian-Sauce"); pizza.setSauce("Hawaiian-Sauce"); } @Override public void buildTopping() { System.out.println("Hawaiian-Topping"); pizza.setTopping("Hawaiian-Topping"); } }SpicyPizzaBuilder.java源码：
package com.andyidea.patterns.concretebuilder; import com.andyidea.patterns.builder.PizzaBuilder; /** * ConcreteBuilder类--具体建造者类 * @author Andy.Chen * */ public class SpicyPizzaBuilder extends PizzaBuilder { @Override public void buildDough() { System.out.println("Spicy-Dough"); pizza.setDough("Spicy-Dough"); } @Override public void buildSauce() { System.out.println("Spicy-Sauce"); pizza.setSauce("Spicy-Sauce"); } @Override public void buildTopping() { System.out.println("Spicy-Topping"); pizza.setTopping("Spicy-Topping"); } }3.4 创建指挥者(Director)类：Waiter.java
package com.andyidea.patterns.director; import com.andyidea.patterns.builder.PizzaBuilder; import com.andyidea.patterns.product.Pizza; /** * Director类--指挥者类 * @author Andy.Chen * */ public 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(); } }3.5 测试类：BuilderClient.java
package com.andyidea.patterns.client; import com.andyidea.patterns.builder.PizzaBuilder; import com.andyidea.patterns.concretebuilder.HawaiianPizzaBuilder; import com.andyidea.patterns.concretebuilder.SpicyPizzaBuilder; import com.andyidea.patterns.director.Waiter; import com.andyidea.patterns.product.Pizza; public class BuilderClient { public static void main(String[] args) { System.out.println("Welcome to Andy.Chen Blog!" +"\n" +"Builder Patterns." +"\n"); Waiter waiter = new Waiter(); PizzaBuilder hawaiian_pizzabuilder = new HawaiianPizzaBuilder(); PizzaBuilder spicy_pizzabuilder = new SpicyPizzaBuilder(); System.out.println("------------HawaiianPizza------------"); waiter.setPizzaBuilder(hawaiian_pizzabuilder); waiter.constructPizza(); System.out.println("------------SpicyPizza------------"); waiter.setPizzaBuilder(spicy_pizzabuilder); waiter.constructPizza(); Pizza pizza = waiter.getPizza(); } }【4】程序运行结果：
Welcome to Andy.Chen Blog! Builder Patterns. ------------HawaiianPizza------------ Hawaiian-Dough Hawaiian-Sauce Hawaiian-Topping ------------SpicyPizza------------ Spicy-Dough Spicy-Sauce Spicy-Topping通过上面我们可以看到：建造者模式的好处就是使得建造代码与表示代码分离，由于建造者隐藏了该产品是如何组装的，所以若需要改变一个产品的内部表示，只需要再定义一个具体的建造者就可以了。
