factory.java

此项目是实现,增加,删除,修改,查询图书数据库的功能

package com.hevttc.book.factory;

import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;

/**
 * @author linzhen
 * 
 */
public class Factory {

	static Map<String, String> map = null;

	// 把配置文件中的信息初始化到map中
	static {
		if (map == null) {
			map = new HashMap<String, String>();
			SAXBuilder builder = new SAXBuilder(false);
			URL url = Thread.currentThread().getContextClassLoader()
					.getResource("DaoConfig.xml");
			try {
				Document doc = builder.build(url.getPath());
				Element root = doc.getRootElement();
				List beanlist = root.getChildren("bean");
				for (int i = 0; i < beanlist.size(); i++) {
					Element bean = (Element) beanlist.get(i);
					map.put(bean.getAttributeValue("id"), bean
							.getAttributeValue("class"));
				}
			} catch (JDOMException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	// 根据id获得实现类
	public static Object getImp(String id) {

		Object dao = null;

		try {
			dao = Class.forName(map.get(id)).newInstance();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		return dao;

	}

}