Mybatis基础学习3——Dao层的封装

传统的Dao层的封装

map层的配置

<select id="getUserByid" parameterType="int" resultType="com.hhh.spring.demo.bean.User" >
    SELECT * FROM USER WHERE id = #{id1}
</select>

<select id="getUserByName" parameterType="string" resultType="com.hhh.spring.demo.bean.User">
    <!-- SELECT * FROM USER WHERE username LIKE #{name} -->
    SELECT * FROM USER WHERE username LIKE '%${value}%'
</select>

<insert id="insertUser" parameterType="com.hhh.spring.demo.bean.User" useGeneratedKeys="true" keyProperty="id">
    <selectKey keyProperty="uuid2" resultType="String" order="BEFORE">
        SELECT UUID()
    </selectKey>

    INSERT INTO USER

    (`username`,
    `birthday`,
    `sex`,
    `address`,
    `uuid2`)
    VALUES (#{username},
    #{birthday},
    #{sex},
    #{address},
    #{uuid2});
</insert>

UserDao接口和UserDaoImpl层

public interface UserDao {
    User getUserById(int id);

    List<User> getUserByUserName(String userName);

    void insertUser(User user);
}

public class UserDaoImpl implements UserDao {
    @Override
    public User getUserById(int id) {
        SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
        // 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 执行删除
        User mUser = sqlSession.selectOne("user.getUserByid", 31);
        // 释放对象
        sqlSession.close();
        return mUser;
    }

    @Override
    public List<User> getUserByUserName(String userName) {

        SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
        // 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 执行删除
        List<User> userList = sqlSession.selectList("user.getUserByName", userName);
        sqlSession.close();
        return userList;
    }

    @Override
    public void insertUser(User user) {
        SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
        // 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 执行删除
        sqlSession.insert("user.insertUser", user);
        sqlSession.commit();
        sqlSession.close();
    }
}

应用层

@Test
public void demo1() throws Exception {
    UserDao userDao = new UserDaoImpl();
    User mUser = userDao.getUserById(31);
    System.out.println(mUser);
}

@Test
public void demo2() throws Exception {
    UserDao userDao = new UserDaoImpl();
    List<User> userList = userDao.getUserByUserName("张");
    System.out.println(userList);
}

@Test
public void demo3() throws Exception {
    UserDao userDao = new UserDaoImpl();
    User user = new User();
    user.setUsername("王麻子");
    user.setSex("1");
    user.setBirthday(new Date());
    user.setAddress("深圳黑马");
    userDao.insertUser(user);
}

动态代理开发

规则：

1、nameSpace必须是全路径名

2、接口的方法名必须与sql id一致。

3、接口的入参必须与paramsType一致

4、接口的返回值必须与resultType一致

代码使用

<!--命名空间，用于隔离sql语句-->
<mapper namespace="com.hhh.spring.demo.mapper.UserMapper">
    <!--id: sql 中的id，语句中的位移标识-->
    <!--resultType: 返回转化的对象-->
    <!--#{} 点位符，相当于jdbc的？-->
    <select id="getUserById" parameterType="int" resultType="com.hhh.spring.demo.bean.User" >
        SELECT * FROM USER WHERE id = #{id1}
    </select>

    <select id="getUserByName" parameterType="string" resultType="com.hhh.spring.demo.bean.User">
        <!-- SELECT * FROM USER WHERE username LIKE #{name} -->
        SELECT * FROM USER WHERE username LIKE '%${value}%'
    </select>

    <insert id="insertUser" parameterType="com.hhh.spring.demo.bean.User" useGeneratedKeys="true" keyProperty="id">
        <selectKey keyProperty="uuid2" resultType="String" order="BEFORE">
            SELECT UUID()
        </selectKey>
        INSERT INTO USER
        (`username`,
        `birthday`,
        `sex`,
        `address`,
        `uuid2`)
        VALUES (#{username},
        #{birthday},
        #{sex},
        #{address},
        #{uuid2});
    </insert>
</mapper>

通过mapper进行方法调用

@Override
public User getUserById(int id) {
    SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
    // 创建SqlSession对象
    SqlSession sqlSession = sqlSessionFactory.openSession();
    // 获取映射对象
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    // 执行命令
    User mUser = mapper.getUserById(id);
    // 释放对象
    sqlSession.close();
    return mUser;
}

@Override
public List<User> getUserByUserName(String userName) {

    SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
    // 创建SqlSession对象
    SqlSession sqlSession = sqlSessionFactory.openSession();
    // 获取映射对象
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    // 执行命令
    List<User> userByUserName = mapper.getUserByUserName(userName);
    // 释放对象
    sqlSession.close();
    return userByUserName;
}

@Override
public void insertUser(User user) {
    SqlSessionFactory sqlSessionFactory = SqlSessionnFactoryUtils.getSqlSessionFactory();
    // 创建SqlSession对象
    SqlSession sqlSession = sqlSessionFactory.openSession();
    // 获取映射对象
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    // 执行命令
    mapper.insertUser(user);
    // 执行删除
    sqlSession.commit();
    sqlSession.close();
}