// specifies an abstract interface for creating parts of a product object.
//为创建对象的一个部分指定一个接口
public interface builder{
void buildparta();
void buildpartb();
product getresult();
}
// constructs and assembles parts of the product by impementing the builder interface.
// defines and keeps track of the representation it creates.
// provides an interface for retrieving the product.
public class concretebuilder1 : builder{
private product m_product;
