2 mybatis实现增删改查

张创琦 2022.03.08

所有的配置都基于第一个文件。

0 before after 抽取

    private SqlSession sqlSession;
    private String resource = "mybatis.xml";
    @Before
    public void before() throws IOException {
        //1、读取mybatis的配置文件
        Reader reader = Resources.getResourceAsReader(resource);
        //2、创建SqlSessionFactory对象, 目的是获取sqlSession--根据图纸创建工厂
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //3、创建可以执行SQL语句的SqlSession--工厂创建产品
        sqlSession = sqlSessionFactory.openSession();
    }
    @After
    public void after(){
        sqlSession.close();
    }

1 查询所有结果

<!-- 查询所有结果 -->
    <select id="queryAll" resultType="com.kkb.pojo.Team">
        select * from team;
    </select>

2 根据ID查询

<!-- 根据ID查询 -->
    <!-- parameterType="参数的类型"，目前只支持一个参数 -->
    <!-- #{id}表示参数 id-自定义, 只需要符合命名规范即可, 没有实际对应意义 -->
    <select id="queryById" parameterType="int" resultType="com.kkb.pojo.Team">
        select * from team where teamId=#{id} ;
    </select>

@Test
    public void testFindById() {
        Team team = sqlSession.selectOne("com.kkb.pojo.Team.queryById", 1001);
        System.out.println(team);
    }

3 删除一个球队

<!-- 删除一个球队 -->
    <delete id="del">
        delete from team where teamId=#{id};
    </delete>

@Test
    public void testDel(){
        int num = sqlSession.delete("com.kkb.pojo.Team.del", 1049);
        sqlSession.commit();
        System.out.println(num);
    }

4 删除多个球队

<!-- 删除多个球队-测试ok -->
    <delete id="del2">
        delete from team where location=#{loc};
    </delete>

@Test
    public void testDel2(){
        int num = sqlSession.delete("com.kkb.pojo.Team.del2", "handan");
        sqlSession.commit();
        System.out.println(num); // 2
    }

5 更新球队信息

<!-- 根据球队编号更新信息 -->
    <update id="update" parameterType="com.kkb.pojo.Team">
        update team set teamName=#{teamName}, location=#{location} where teamId=#{teamId}
    </update>

@Test
    public void testUpdate(){
        Team team = sqlSession.selectOne("com.kkb.pojo.Team.queryById", 1054);
        team.setTeamName("zhangchuangqi的球队");
        team.setLocation("洛杉矶");
        int num = sqlSession.update("com.kkb.pojo.Team.update", team);
        sqlSession.commit();
        System.out.println(num);
    }

6 添加一个球队

<!-- 添加一个球队 -->
    <!-- parameterType="com.kkb.pojo.Team" 将对象作为参数.
    注意 `` 符号的输入
    #{值} 值必须是实体类中的属性名称，其实就是占位符 ?  -->
    <insert id="add" parameterType="com.kkb.pojo.Team">
        INSERT INTO `team` (`teamName`, `location`, `createTime`)
        VALUES (#{teamName}, #{location}, #{createTime})
    </insert>

@Test
    public void testAdd() {
        Team team = new Team();
        team.setTeamName("zhang的球队2");
        team.setLocation("邯郸");
        team.setCreateTime(new Date());
        int num = sqlSession.insert("com.kkb.pojo.Team.add", team);
        sqlSession.commit();
        System.out.println(num);
    }

‘