建造者模式

第一步：创建一个产品，及产品的各个部件；

public class Product {

    List<String> parts = new ArrayList<String>();

    public void addPart(String part) {
        if (StringUtils.isNotBlank(part)) {
            parts.add(part);
        }
    }

    public void showParts() {
        for (String part : parts) {
            System.out.println(part);
        }
    }
}

第二步：创建一个抽象建造者，把产品的各个部件分离出来分别构建

public abstract class AbstractBuilder {

    public abstract void buildA();
    public abstract void buildB();
    public abstract Product getProduct();
}

第三步：创建具体建造者

public class ConcreteBuilder1 extends AbstractBuilder {

    private Product product;
    @Override
    public void buildA() {
        product.addPart("部件A");
    }

    @Override
    public void buildB() {
        product.addPart("部件B");
    }

    @Override
    public Product getProduct() {
        return product;
    }

}

public class ConcreteBuilder2 extends AbstractBuilder {

    private Product product;
    @Override
    public void buildA() {
        product.addPart("部件C");
    }

    @Override
    public void buildB() {
        product.addPart("部件D");
    }

    @Override
    public Product getProduct() {
        return product;
    }

}

第四步：创建指挥者

public class Director {

    public void control(AbstractBuilder builder) {
        builder.buildA();
        builder.buildB();
    }
}

第五步：指挥者指挥创建者创建产品，完成不同产品创建

public static void main(String[] args) {
        Director director = new Director();
        AbstractBuilder builder1 = new ConcreteBuilder1();
        AbstractBuilder builder2 = new ConcreteBuilder2();
        director.control(builder1);
        Product p1 = builder1.getProduct();
        p1.showParts();
        director.control(builder2);
        Product p2 = builder2.getProduct();
        p2.showParts();
}