工厂＋配置文件实现分层

package cn.jxau.factory;

import java.io.IOException;
import java.util.Properties;

public class DaoFactory {

	private static Properties prop = new Properties();

	// 将工厂类设计成单例模式
	private DaoFactory() {
		try {
			prop.load(DaoFactory.class.getClassLoader().getResourceAsStream(
					"dao.properties"));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			throw new RuntimeException();
		}
	}

	private static DaoFactory instance = new DaoFactory();

	public static DaoFactory getInstance() {
		return instance;
	}

	// 送进来的是什么类型工厂就为你造什么类型的dao,java中把所有的类也抽取成了一个类叫Class
	public static 
 
   T getdao(Class
  
    clazz) { // 获得传进来的接口名用于反射出一个对象实例 String name = clazz.getSimpleName();// 得到一个不带包名的接口名 String classname = prop.getProperty(name);//通过具体的配置文件获取具体的类名 T dao = null; try { dao = (T) Class.forName(classname).newInstance();//反射实例出一个对象 } catch (Exception e) { // TODO Auto-generated catch block throw new RuntimeException(e); } return dao; } }
  
 

UserDao=cn.jxau.dao.impl.UserDaoJdbcImpl