1 package com.fjdingsd.daoimpl;
 2 public class UserDaoImpl implements UserDao {
 3     @Override
 4     public void insert(){
 5         。。。//添加User对象
 6     }
 7
 8     @Override
 9     public void delete() {
10         。。。//删除User对象
11     }
12
13     @Override
14     public void update() {
15         。。。//修改User对象
16     }
17
18     @Override
19     public void find() {
20         。。。//查找User对象
21     }
22 }

1 package com.fjdingsd.dao;
2 public interface UserDao {
3     public abstract void insert();
4     public abstract void delete();
5     public abstract void update();
6     public abstract void find();
7 }

 1 package com.fjdingsd.factory;
 2 public class DaoFactory {
 3
 4     private static DaoFactory instance = new DaoFactory();
 5     private Properties config = new Properties();
 6
 7     private DaoFactory(){
 8         InputStream in = DaoFactory.class.getClassLoader().getResourceAsStream("factory.properties");    //读取配置文件装载进输入流
 9         try {
10             config.load(in); //将配置文件封装进Properties对象中
11
12         } catch (IOException e) {
13             e.printStackTrace();
14         }
15     }
16
17     public static DaoFactory getInstance() {
18         return instance;
19     }
20
21     public <T> T createDao(Class<T> clazz) {
22         String interfaceName = clazz.getSimpleName();//获取配置文件中的接口关键字
23         String className = config.getProperty(interfaceName); //根据接口名获取配置文件中的具体实现类完整名称
24         try {
25             T bean = (T) Class.forName(className).newInstance();//使用反射创建实现类的一个实例对象
26             return bean;
27         } catch (Exception e) {
28             throw new RuntimeException(e);
29         }
30     }
31 }

1 package com.fjdingsd.service.impl;
2 public class BussinessServiceImpl {
3
4     //UserDao uDao = new UserDaoImpl();  以前未使用工厂模式加泛型之前的写法
5     UserDao uDao = DaoFactory.getInstance().createDao(UserDao.class);
6     。。。//其他代码，此处略
7 }