java 使用BeanFactory实现service与dao层解耦合详解

UserDao UserDao=new UserDaoImpl();

UserDao UserDao=(UserDao)BeanFactory.createObject("UserDao");

package cn.itcast.store.service.serviceImp; 
import java.sql.SQLException; 
import cn.itcast.store.dao.UserDao;
import cn.itcast.store.dao.daoImp.UserDaoImp;
import cn.itcast.store.domain.User;
import cn.itcast.store.service.UserService;
import cn.itcast.store.utils.BeanFactory; 
public class UserServiceImp implements UserService {
 UserDao UserDao=(UserDao)BeanFactory.createObject("UserDao"); 
 
 @Override
 public void userRegist(User user) throws SQLException {
  //实现注册功能  
  UserDao.userRegist(user);  
 }
 
 @Override
 public boolean userActive(String code) throws SQLException {
  //实现注册功能
  
  ///对DB发送select * from user where code=?
  User user=UserDao.userActive(code);  
  if(null!=user){
   //可以根据激活码查询到一个用户
   //修改用户的状态,清除激活码
   user.setState(1);
   user.setCode(null);
   //对数据库执行一次真实的更新操作  update user set state=1 , code=null where uid=?
   //update user set username=? , password=? ,name =? ,email=?, telephone =? ,birthday =? ,sex=? ,state=? ,code= ? where uid=?
   UserDao.updateUser(user);
   return  true;
  }else{
   //不可以根据激活码查询到一个用户
   return false;
  }
 }
 
 @Override
 public User userLogin(User user) throws SQLException {
  //此处:可以利用异常在模块之间传递数据   
  
  //select * from user where username=? and password=?
  User uu=UserDao.userLogin(user);
  if(null==uu){
   throw new RuntimeException("密码有误!");
  }else if(uu.getState()==0){
   throw new RuntimeException("用户未激活!");
  }else{
   return uu;
  }
 } 
}

package cn.itcast.store.utils; 
import java.io.InputStream;
import java.sql.SQLException;
import java.util.List; 
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader; 
import cn.itcast.store.dao.UserDao;
import cn.itcast.store.domain.User; 
public class BeanFactory { 
 
 //解析XML
 public static Object createObject(String name) {
  try {
   //通过传递过来的name获取application.xml中name对应的class值
   
   //获取到Document对象
   SAXReader reader=new SAXReader();
   //如果获取application.xml文件的输入流 (application.xml必须位于src下)
   InputStream is=BeanFactory.class.getClassLoader().getResourceAsStream("application.xml");
   Document doc=reader.read(is);
   //通过Document对象获取根节点  beans
   Element rootElement = doc.getRootElement();
   //通过根节点获取到根节点下所有的子节点 bean,返回集合
   List<Element> list = rootElement.elements();
   //遍历集合,判断每个元素上的id的值是否和当前的name一致
   for (Element ele : list) {
    //ele相当于beans节点下的每个bean
    //获取到当前节点的id属性值
    //如果一致,获取到当前元素上class属性值
    String id=ele.attributeValue("id");
    if(id.equals(name)){
     String str=ele.attributeValue("class");
     //通过反射创建对象并且返回
     Class clazz=Class.forName(str);
     //利用class值通过反射创建对象返回
     return  clazz.newInstance();     
    }
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  return null;
 }
 
 public static void main(String[] args) throws SQLException {
  UserDao ud=(UserDao)BeanFactory.createObject("UserDao");
  User user=new User();
  user.setUsername("aaa");
  user.setPassword("aaa");
  User uu = ud.userLogin(user);
  System.out.println(uu);
 } 
}

<?xml version="1.0" encoding="UTF-8"?>
<beans>
   <bean id="CategoryDao" class="cn.itcast.store.dao.daoImp.CategoryDaoImp"/>
   <bean id="UserDao" class="cn.itcast.store.dao.daoImp.UserDaoImp"/>
   <bean id="ProductDao" class="cn.itcast.store.dao.daoImp.ProductDaoImp"/>
</beans>

public class CreatFactory {
 //单例模式 
 private static SqlSessionFactory factory=null;
 public static SqlSessionFactory creatFactory(){
  if(factory==null){
   //加载配置文件
   String resource = "mybatis/config.xml";//配置文件地址
   //读取文件resource,变成字符流
   Reader reader;
   try {
    reader = Resources.getResourceAsReader(resource);
    //将字符流,相当于Connection
    factory= new SqlSessionFactoryBuilder().build(reader);
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  return factory;
 }
}