初识MyBatis

框架技术

　主流框架

　持久化与ORM

MyBatis

　简介

　环境搭建

　　导入mybatis-3.2.3.jar包（可添加源码）

　　MyBatis配置文件mybatis-config.xml（resources目录下）

<?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">

<!-- 通过这个配置文件完成mybatis与数据库的连接 -->
<configuration>
    <!-- 引入 database.properties 文件-->
    <properties resource="database.properties"/>
    <!-- 配置mybatis的log实现为LOG4J -->
    <settings>
        <setting name="logImpl" value="LOG4J" />
    </settings>
    <environments default="development">
        <environment id="development">
            <!--配置事务管理，采用JDBC的事务管理  -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- POOLED:mybatis自带的数据源，JNDI:基于tomcat的数据源 -->
            <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>
    
    <!-- 将mapper文件加入到配置文件中 -->
    <mappers>
        <mapper resource="cn/smbms/dao/user/UserMapper.xml"/>
    </mappers>

</configuration>

　　实体类User.java（cn.smbms.pojo目录下）

　　DAO层-SQL映射文件UserMapper.xml（cn.smbms.dao.user目录下）

<?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="cn.smbms.dao.user.UserMapper">
    
    <!-- 查询用户表的记录数 -->
    <select id="count" resultType="int">
        select count(1) as count from smbms_user
    </select>
    
    <!-- 查询用户列表 -->
    <select id="getUserList" resultType="cn.smbms.pojo.user.User">
        select * from smbms_user
    </select>
    
</mapper

　　工具类

public class MyBatisUtil {
    private static SqlSessionFactory factory;

    static {
        try {
            // 1、获取mybatis-config.xml输入流
            InputStream is = Resources
                    .getResourceAsStream("mybatis-config.xml");
            // 2、创建SqlSessionFactory对象，完成对配置文件的读取
            factory = new SqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSession openSqlSession() {
        return factory.openSession();
    }

    public static void closeSqlSession(SqlSession sqlSession) {
        if (null != sqlSession) {
            sqlSession.close();
        }
    }

}

　　测试类

public class UserMapperTest {
    private Logger logger = Logger.getLogger(UserMapperTest.class);

    @Test
    public void test() {
        // 3、创建SqlSession
        SqlSession sqlSession = MyBatisUtil.openSqlSession();
        // 4、调用mapper文件来对数据进行操作，必须先把mapper文件引入到mybatis-config.xml中
        int count = sqlSession.selectOne("cn.smbms.dao.user.UserMapper.count");
        logger.debug("UserMapperTest count ----> " + count);
        MyBatisUtil.closeSqlSession(sqlSession);
    }

    @Test
    public void testGetUserList() {
        // 3、创建SqlSession
        SqlSession sqlSession = MyBatisUtil.openSqlSession();
        // 4、调用mapper文件来对数据进行操作，必须先把mapper文件引入到mybatis-config.xml中
        List<User> userList = sqlSession
                .selectList("cn.smbms.dao.user.UserMapper.getUserList");
        for (User user : userList) {
            logger.debug("userName" + user.getUserName());
        }
        MyBatisUtil.closeSqlSession(sqlSession);
    }

}