我的测试类找不到mybatis的xml文件

package com.san.library.dao;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;


public class DaoFactory {
   private static DaoFactory daoFactory;
   private SqlSessionFactory sqlSessionFactory;

   private DaoFactory(){
       SqlSessionFactoryBuilder sqlSessionFactoryBuilder=new SqlSessionFactoryBuilder();

       try {
           sqlSessionFactory= sqlSessionFactoryBuilder.build(Resources.getResourceAsReader("/mybatis-config.xml"));
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

   public static DaoFactory getInstance(){
       if (daoFactory==null){
           daoFactory=new DaoFactory();
       }
       return daoFactory;
   }

   public <T> T getDao(Class<T> tClass){
       return sqlSessionFactory.openSession(true).getMapper(tClass);
   }
}

明明就是在resource下，怎么就找不到呢