1、原始Dao開發方法需要程式設計師編寫Dao介面和Dao實現類。

2、編寫對映檔案

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="test">
<!-- 根據id獲取使用者資訊 -->
	<select id="findUserById" parameterType="int" resultType="cn.chuantao.mybatis.po.User">
		select * from user where id = #{id}
	</select>
<!-- 新增使用者 -->
	<insert id="insertUser" parameterType="cn.itcast.mybatis.po.User">
	<selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
		select LAST_INSERT_ID() 
	</selectKey>
	  insert into user(username,birthday,sex,address) 
	  values(#{username},#{birthday},#{sex},#{address})
	</insert>
</mapper>
 

3、Dao層介面

Public interface UserDao {
	public User getUserById(int id) throws Exception;
	public void insertUser(User user) throws Exception;
}

4、Dao實現類

Public class UserDaoImpl implements UserDao {
	
	//通過構造方法的方式注入SqlSessionFactory
	public UserDaoImpl(SqlSessionFactory sqlSessionFactory){
		this.setSqlSessionFactory=sqlSessionFactory;
	}
	
	private SqlSessionFactory sqlSessionFactory;
	@Override
	public User getUserById(int id) throws Exception {
		SqlSession session = sqlSessionFactory.openSession();
		User user = null;
		try {
			//通過sqlsession呼叫selectOne方法獲取一條結果集
			//引數1：指定定義的statement的id,引數2：指定向statement中傳遞的引數
			user = session.selectOne("test.findUserById", 1);
			System.out.println(user);
						
		} finally{
			session.close();
		}
		return user;
	}
	
	@Override
	Public void insertUser(User user) throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		try {
			sqlSession.insert("insertUser", user);
			sqlSession.commit();
		} finally{
			session.close();
		}
		
	}
}
 

5、測試

private SqlSessionFactory sqlSessionFactory;
	
	@Before
	public void init() throws Exception {
		SqlSessionFactoryBuilder sessionFactoryBuilder = new SqlSessionFactoryBuilder();
		InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
		sqlSessionFactory = sessionFactoryBuilder.build(inputStream);
	}

	@Test
	public void testGetUserById() {
		UserDao userDao = new UserDaoImpl(sqlSessionFactory);
		User user = userDao.getUserById(22);
		System.out.println(user);
	}
}
 

6、存在的問題

原始Dao開發中存在以下問題：
Dao方法體存在重複程式碼：通過SqlSessionFactory建立SqlSession，呼叫SqlSession的資料庫操作方法
呼叫sqlSession的資料庫操作方法需要指定statement的id，這裡存在硬編碼，不利於開發維護。