建造者模式（Java與Kotlin版）

 1 class Product {
 2     private String name;
 3     private int price;
 4 
 5     public void setName(String name_arg) {
 6         name = name_arg;
 7     }
 8 
 9     public void setPrice(int price_arg) {
10         price = price_arg;
11     }
12 
13     public void show() {
14         System.out.println("名字: " + name + ", 價格： " + price);
15     }
16 }

除了兩個屬性的set方法，還定義了一個打印屬性的show方法。

Director：

 1 class Director {
 2     AbstractBuilder builder;
 3 
 4     public void setBuilder(AbstractBuilder builder_arg) {
 5         builder = builder_arg;
 6     }
 7 
 8     public Product construct() {
 9         builder.buildName();
10         builder.buildPrice();
11 
12         return builder.getProduct();
13     }
14 }

經過設置的建造者，建立產品實例並返回。

AbstractBuilder：

1 abstract class AbstractBuilder {
2     abstract public void buildName();
3     abstract public void buildPrice();
4     abstract public Product getProduct();
5 }

定義了三個抽象方法，用於設置產品屬性及獲取實例。

ConcreteBuilder1與ConcreteBuilder2：

 1 class ConcreteBuilder1 extends AbstractBuilder {
 2     private Product product;
 3 
 4     public ConcreteBuilder1() {
 5         product = new Product();
 6     }
 7 
 8     public void buildName() {
 9         product.setName("套餐1");
10     }
11 
12     public void buildPrice() {
13         product.setPrice(1);
14     }
15 
16     public Product getProduct() {
17         return product;
18     }
19 }

 1 class ConcreteBuilder2 extends AbstractBuilder {
 2     private Product product;
 3 
 4     public ConcreteBuilder2() {
 5         product = new Product();
 6     }
 7 
 8     public void buildName() {
 9         product.setName("套餐2");
10     }
11 
12     public void buildPrice() {
13         product.setPrice(2);
14     }
15 
16     public Product getProduct() {
17         return product;
18     }
19 }

具體建造者，實現產品的建立。

測試代碼：

 1 public class BuilderPattern {
 2     public static void main(String[] args) {
 3         System.out.println("Builder Pattern");
 4 
 5         Product product;
 6 
 7         Director director = new Director();
 8 
 9         AbstractBuilder builder1 = new ConcreteBuilder1();
10         director.setBuilder(builder1);
11         product = director.construct();
12         product.show();
13 
14         AbstractBuilder builder2 = new ConcreteBuilder2();
15         director.setBuilder(builder2);
16         product = director.construct();
17         product.show();
18     }
19 }

輸出：

3.2 Kotlin

Product：

 1 class Product {
 2     private var name: String? = null
 3     private var price: Int = 0
 4 
 5     fun setName(name_arg : String) {
 6         name = name_arg
 7     }
 8 
 9     fun setPrice(price_arg : Int) {
10         price = price_arg
11     }
12 
13     fun show() {
14         println("名字: $name, 價格： $price")
15     }
16 }

Director：

 1 class Director {
 2     private var builder: AbstractBuilder? = null
 3 
 4     fun setBuilder(builder_arg: AbstractBuilder) {
 5         builder = builder_arg
 6     }
 7 
 8     fun construct(): Product {
 9         builder?.buildName()
10         builder?.buildPrice()
11 
12         return builder!!.getProduct()
13     }
14 }

AbstractBuilder：

1 abstract class AbstractBuilder {
2     abstract fun buildName()
3     abstract fun buildPrice()
4     abstract fun getProduct(): Product
5 }

ConcreteBuilder1與ConcreteBuilder2：

 1 class ConcreteBuilder1 : AbstractBuilder() {
 2     private val product: Product
 3 
 4     init {
 5         product = Product()
 6     }
 7 
 8     override fun buildName() {
 9         product.setName("套餐1")
10     }
11 
12     override fun buildPrice() {
13         product.setPrice(1)
14     }
15 
16     override fun getProduct(): Product {
17         return product
18     }
19 }

 1 class ConcreteBuilder2 : AbstractBuilder() {
 2     private val product: Product
 3 
 4     init {
 5         product = Product()
 6     }
 7 
 8     override fun buildName() {
 9         product.setName("套餐2")
10     }
11 
12     override fun buildPrice() {
13         product.setPrice(2)
14     }
15 
16     override fun getProduct(): Product {
17         return product
18     }
19 }

測試代碼：

 1 fun main(array: Array<String>) {
 2     println("Builder Pattern")
 3 
 4     var product: Product? = null
 5 
 6     val director = Director()
 7 
 8     val builder1 = ConcreteBuilder1()
 9     director.setBuilder(builder1)
10     product = director.construct()
11     product.show()
12 
13     val builder2 = ConcreteBuilder2()
14     director.setBuilder(builder2)
15     product = director.construct()
16     product.show()
17 }