设计模式（五）建造

1、产品类：

public class Product {

	private String bottom;
	private String center;
	private String top;

	public Product() {
	}

	public void setBottom(String bottom) {
		this.bottom = bottom;
	}

	public void setCenter(String center) {
		this.center = center;
	}

	public void setTop(String top) {
		this.top = top;
	}

	public void show() {
		System.out.println("这是一间漂亮的房子！"+" 地基："+bottom+"  主体："+center+"  屋顶："+top);
	}

}

2.建造者类

public class Builder {
	
	private static final int  READY=0;
	private static final int  BOTTOM_IS_OK=1;
	private static final int  CENTER_IS_OK=2;
	private static final int  TOP_IS_OK=3;
	
	private int state=READY;
	
	private Product product = new Product();

	public void buildBottom(){
		if(state==READY){
			System.out.println("建造地基！");
			product.setBottom("钢筋混凝土");
			state=BOTTOM_IS_OK;
		}
	}
	
	public void buildCenter(){
		if(state==BOTTOM_IS_OK){
			System.out.println("建造主体！");
			product.setCenter("钢结构组件");
			state=CENTER_IS_OK;
		}
	}
	
	public void buildTop(){
		if(state==CENTER_IS_OK){
			System.out.println("建造屋顶！");
			product.setTop("木结构组件");
			state=TOP_IS_OK;
		}
	}

	public Product getProduct() {
		if(state!=TOP_IS_OK){
			product=null;
		}
		return product;
	}

3.导演类

public class Director {

	public Product build() {
		
		Builder builder=new Builder();
		
		builder.buildBottom();
		builder.buildCenter();
		builder.buildTop();
		
		Product product = builder.getProduct();
		
		return product;
	}
}

4.消费者

public class Customer {

	public static void main(String[] args) {
		
		Director director=new Director();
		Product product=director.build();
		
		if(product==null){
			System.out.println("房子没有建好！");
		}else{
			product.show();
		}

	}

}