【模式UML图】
【模式代码(JAVA语言实现)】
//服务员
//食物套餐
//生产套餐抽象类
//套餐A
//套餐B
//客户端
public class Client
{
public static void main(String args[])
{
//动态确定套餐种类
MealBuilder mb=(MealBuilder)XMLUtil.getBean();
//服务员是指挥者
KFCWaiter waiter=new KFCWaiter();
//服务员准备套餐
waiter.setMealBuilder(mb);
//客户获得套餐
Meal meal=waiter.construct();
System.out.println("套餐组成:");
System.out.println(meal.getFood());
System.out.println(meal.getDrink());
}
}
//提取配置文件
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
import java.io.*;
public class XMLUtil
{
//该方法用于从XML配置文件中提取具体类类名,并返回一个实例对象
public static Object getBean()
{
try
{
//创建文档对象
DocumentBuilderFactory dFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = dFactory.newDocumentBuilder();
Document doc;
doc = builder.parse(new File("config.xml"));
//获取包含类名的文本节点
NodeList nl = doc.getElementsByTagName("className");
Node classNode=nl.item(0).getFirstChild();
String cName=classNode.getNodeValue();
//通过类名生成实例对象并将其返回
Class c=Class.forName(cName);
Object obj=c.newInstance();
return obj;
}
catch(Exception e)
{
e.printStackTrace();
return null;
}
}
}
//配置文件config
<?xml version="1.0"?>
<config>
<className>SubMealBuilderB</className>
</config>