建造者模式

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

下面是Builder的结构图：

 

下面演示一个Demo：

创建一个产品类，由多个部件组成：

public class Product {List<String> parts = new ArrayList<String>();public void add(String part) {parts.add(part);}public void show() {System.out.println("产品创建：");for(String str : parts)System.out.println(str);}}

 

Builder接口：

public interface Builder {public void buildPartA();public void buildPartB();public Product getResult();}

 

两个具体的建造类：

class ConcreteBuilder1 implements Builder{private Product product = new Product();@Overridepublic void buildPartA() {product.add("部件A");}@Overridepublic void buildPartB() {product.add("部件B");}@Overridepublic Product getResult() {return product;}}class ConcreteBuilder2 implements Builder {private Product product = new Product();@Overridepublic void buildPartA() {product.add("部件C");}@Overridepublic void buildPartB() {product.add("部件D");}@Overridepublic Product getResult() {return product;}}

 

Director指挥类：

public class Director {public void construct(Builder builder) {builder.buildPartA();builder.buildPartB();}}

 

客户端：

public class Client {public static void main(String[] args) {Director director = new Director();Builder builder1 = new ConcreteBuilder1();Builder builder2 = new ConcreteBuilder2();director.construct(builder1);Product product1 = builder1.getResult();product1.show();director.construct(builder2);Product product2 = builder2.getResult();product2.show();}}