Mybatis学习一

使用Mybatis实现CRUD

​ 更多了解请阅读官方文档

第一步：配置Mybatis核心xml文件

<?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">
<!--核心配置文件-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="lol2020."/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/px/dao/UserMapper.xml"/>
    </mappers>
</configuration>

第二部：连接数据库、编写实体类、接口声明

第三步：编写工具类获取SqlSessionFactory

public class MybatisUtils {

    /**使用mybatis获取SqlSessionFactory工具类**/
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

第四步：编写Mapper.xml文件与接口类绑定，并编写sql标签

<?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="com.px.dao.UserMapper">
    <select id="getUserList" resultType="com.px.pojo.User">
    select * from mybatis.user
    </select>

    <select id="getUserById" parameterType="int" resultType="com.px.pojo.User">
        select * from mybatis.user where id = #{id}
    </select>

    <insert id="insertUser" parameterType="com.px.pojo.User">
        insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd})
    </insert>

    <delete id="deleteUser" parameterType="int">
        delete from mybatis.user where id = #{id}
    </delete>

    <update id="updateUserById" parameterType="com.px.pojo.User">
        update mybatis.user set name = #{name}, pwd = #{pwd} where id = #{id}
    </update>

</mapper>

第五步：编写测试类

public class UserDaoTest {

    @Test
    public void test() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> list = mapper.getUserList();
            for (User user : list) {
                System.out.println(user);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            sqlSession.close();
        }
    }

    @Test
    public void getUserById() {

        try (SqlSession sqlSession = MybatisUtils.getSqlSession()) {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            User userById = mapper.getUserById(2);
            System.out.println(userById);
        }
    }
    
    @Test
    public void insertUser() {
        
        try (SqlSession sqlSession = MybatisUtils.getSqlSession()) {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            mapper.insertUser(new User(6, "赵六", "123456"));
            sqlSession.commit();
        }
    }

    @Test
    public void deleteUser() {
        
        try (SqlSession sqlSession = MybatisUtils.getSqlSession()) {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            mapper.deleteUser(6);
            sqlSession.commit();
        }
    }

    @Test
    public void updateUserById() {

        try (SqlSession sqlSession = MybatisUtils.getSqlSession()) {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            mapper.updateUserById(new User(2, "中文", "654321"));
            sqlSession.commit();
        }
    }
}