objectpoolfactory.java

疯狂Java讲义_源码(含Java设计模式CHM

import java.util.*;
import java.io.*;
/**
 * Description:
 * <br/>Copyright (C), 2008-2010, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class ObjectPoolFactory
{
	//定义一个对象池,前面是对象名，后面是实际对象
	private Map<String ,Object> objectPool = 
		new HashMap<String , Object>();
	//定义一个创建对象的方法，
	//该方法只要传入一个字符串类名，程序可以根据该类名生成Java对象
	private Object createObject(String clazzName)
		throws InstantiationException , IllegalAccessException
		,ClassNotFoundException
	{
		//根据字符串来获取对应的Class对象
		Class<?> clazz =Class.forName(clazzName);
		//使用clazz对应类的默认构造器创建实例
		return clazz.newInstance();		
	}
	//该方法根据指定文件来初始化对象池，
	//它会根据配置文件来创建对象
	public void initPool(String fileName)
		throws InstantiationException , IllegalAccessException
		,ClassNotFoundException
	{
		FileInputStream fis = null;
		try
		{
			fis = new FileInputStream(fileName);
			Properties props = new Properties();
			props.load(fis);
			for (String name : props.stringPropertyNames())
			{
				//每取出一对属性名－属性值对，就根据属性值创建一个对象
				//调用createObject创建对象，并将对象添加到对象池中
				objectPool.put(name , 
					createObject(props.getProperty(name))); 
			}
 
		}
		catch (IOException ex)
		{
			System.out.println("读取" + fileName + "异常");
		}
		finally
		{
			try
			{
				if (fis != null)
				{
					fis.close();
				}
			}
			catch (IOException ex)
			{
				ex.printStackTrace();
			}
		}
	}
	public Object getObject(String name)
	{
		//从objectPool中取出指定name对应的对象。
		return objectPool.get(name);
	}
	
	public static void main(String[] args)
		throws Exception
	{
		ObjectPoolFactory pf = new ObjectPoolFactory();
		pf.initPool("obj.txt");
		System.out.println(pf.getObject("a"));
	}
}