SSM项目集成mybatis出错，哪位大佬帮帮忙

Question

网上说的namespace 和接口名相同我都看了没什么问题

接口

 import com.sztaiji.entity.User;

public interface UserDAO {
    public User findByUsername(String username);
    public void save(User user);
}

实现类

import javax.annotation.Resource;

import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.stereotype.Repository;

import com.sztaiji.entity.User;
@Repository("userDAO")
public class UserDAOImpl implements UserDAO {
    @Resource(name="sst")
    private SqlSessionTemplate sst;

    public User findByUsername(String username) {


        return sst.selectOne("com.sztaiji.dao.findByUsername", username);
    }

    public void save(User user) {
        sst.insert("com.sztaiji.dao.save", user);
    }

}

映射文件

 <?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE mapper PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"      
 "http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">
 <mapper namespace="com.sztaiji.dao.UserDAO">
    <insert id="save" parameterType="com.sztaiji.entity.User">
        insert into tb_user(username,pwd,name) values(#{username},#{pwd},#{name})
    </insert>

    <select id=" findByUsername" parameterType="String" resultType="com.sztaiji.entity.User">
        select * from tb_user where username=#{username}
    </select>
 </mapper>

Answer 1

不是不用写dao的实现类啊， 直接写一个dao的接口就行了，然后直接去对应xml的id了么