mybatis开发dao的方式

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

public class UserDaoImpl implements UserDao {
    private SqlSessionFactory sqlSessionFactory;
    public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }
    public UserDaoImpl() {
        super();
    }
    @Override
    public User getUserById(int id) throws Exception {
        //获取sqlSession,需要使用sqlSessionFactory
        SqlSession session = sqlSessionFactory.openSession();
        try {
            User user = session.selectOne("selectUserById", id);
            return user;
        } finally{
            session.close();
        }
    }
    @Override
    public void insertUser(User user) throws Exception {
        //获取sqlSession,需要使用sqlSessionFactory
        SqlSession session = sqlSessionFactory.openSession();
        try {
            session.insert("insertUser", user);
            session.commit();
        } finally{
            session.close();
        }
    }
}

<?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="mybatis.mapper.UserMapper">
    <!-- 根据id获取用户信息 -->
    <select id="selectUserById" parameterType="int" resultType="user">
        select * from user where id = #{id}
    </select>

    <!-- 向数据库插入一条数据 -->
    <insert id="insertUser" parameterType="user">
    <selectKey keyProperty="id" resultType="int" order="AFTER">
        select last_insert_id();
    </selectKey>
        insert into user(username,birthday,sex,address) 
            values(#{username},#{birthday},#{sex},#{address})
    </insert>

</mapper>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!-- 加载外部配置文件 -->
    <properties resource="db.properties">
    </properties>


    <!-- 这个environments定义了我们的数据库的连接操作 -->
      <environments default="development">
        <environment id="development">
          <transactionManager type="JDBC"/>
          <dataSource type="POOLED">
            <property name="driver" value="${driver}"/>
            <property name="url" value="${url}"/>
            <property name="username" value="${username}"/>
            <property name="password" value="${password}"/>
          </dataSource>
        </environment>
      </environments>
      <!-- 通过mappers来指定加载我们对应的mapper文件 -->
        <mappers>
            <mapper resource="UserMapper.xml"/> 
        </mappers>
</configuration>

public class UserDaoTest {

    private SqlSessionFactory getSqlSessionFactory() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }

    @Test
    public void testGetUserById() throws Exception {
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
        UserDao userDao = new UserDaoImpl(sqlSessionFactory);
        User user = userDao.getUserById(1);
        System.out.println(user);
    }

    @Test
    public void testInsertUser() throws Exception {
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
        UserDao userDao = new UserDaoImpl(sqlSessionFactory);
        User user = new User();
        user.setUsername("安茱莉");
        user.setSex("0");
        user.setAddress("好莱坞38号");
        userDao.insertUser(user);
    }
}

public interface UserMapper {
        // 根据id查找用户
        public User findUserById(int id) throws Exception;

        // 插入用户信息
        public void insertUser(User user) throws Exception;
}

<?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="mybatis.mapper.UserMapper">
    <!-- 根据id获取用户信息 -->
    <select id="findUserById" parameterType="int" resultType="user">
        select * from user where id = #{id}
    </select>

    <!-- 向数据库插入一条数据 -->
    <insert id="insertUser" parameterType="user">
        insert into user(username,birthday,sex,address) 
            values(#{username},#{birthday},#{sex},#{address})
    </insert>
</mapper>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!-- 别名的配置 -->
    <typeAliases>
        <!-- 不区分大小写的 -->
        <!-- <typeAlias type="domain.User" alias="user"/> -->
        <!-- 扫描这个包下面的所有类，起别名，也是不区分大小写的 ,名字是类名不带包，推荐这种方式-->
        <package name="domain"/>
    </typeAliases>

    <!-- 加载外部配置文件 -->
    <properties resource="db.properties">
    </properties>

    <!-- 这个environments定义了我们的数据库的连接操作 -->
      <environments default="development">
        <environment id="development">
          <transactionManager type="JDBC"/>
          <dataSource type="POOLED">
            <property name="driver" value="${driver}"/>
            <property name="url" value="${url}"/>
            <property name="username" value="${username}"/>
            <property name="password" value="${password}"/>
          </dataSource>
        </environment>
      </environments>

        <!-- 通过mappers来指定加载我们对应的mapper文件 -->
        <!-- 此种方法要求mapper接口名称和mapper映射文件名称相同，且放在同一个目录中。 -->
          <mappers>
            <mapper resource="mapper.xml"/>
    <!--    <mapper class="mybatis.mapper.UserMapper"/> -->
    <!-- 加载包下所有mapper接口，要求接口名称和mapper映射文件名称相同，且放在同一个目录中。 -->
            <package name="mybatis.mapper"/>
          </mappers>
</configuration>

public class UserMapperTest {

    /**
     * 通过接口代理开发dao层的测试
     * 调用getUserById方法，传递id参数
     * 输出user对象到控制台
     */
    @Test
    public void findUserByIdTest() throws Exception{
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //mybatis会产生一个代理对象
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user = mapper.getUserById(2);
        System.out.println(user);
        sqlSession.close();
    }

    ...

    /**
     * 抽取方法，保证项目中SQLSessionFactory的单例
     */
    private SqlSessionFactory getSqlSessionFactory() throws IOException {
        InputStream inputStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }
}