Mybatis（三）：批量操作

批量操作分为批量插入和批量更新
主要使用<foreach>

<foreach collection="list" item="item" open="(" close=")" separator="," index="index">
   #{item.xx}, #{item.xx}
</foreach>

属性注释：
collection="list"    其中list是固定的，如果是数组就是array
item="item"         循环中每一项的别名
open=""             开始标识，比如删除in (id1,id2)， open="(" close=")"
close=""            结束标识
separator=","       分隔符号
index="index"       下标值

批量新增

<!-- 批量保存用户,并返回每个用户插入的ID -->
<insert id="batchSave" parameterType="java.util.List" useGeneratedKeys="true" keyProperty="id">
    INSERT INTO `test`.`tb_user`(`username`, age)
    VALUES
    <foreach collection="list" item="item" separator=",">
        (#{item.username}, #{item.age})
    </foreach>
</insert>

批量删除

<!-- 批量删除用户 -->
<delete id="batchDelete" parameterType="java.util.List">
    DELETE FROM `test`.`tb_user` WHERE id IN
    <foreach collection="list" item="item" open="(" close=")" separator=",">
        #{id}
    </foreach>
</delete>

UserMapper

public interface UserMapper {

    /**
     * 批量保存用户
     * @param userList
     */
    int batchSave(List<User> userList);

    /**
     * 批量删除用户
     * @param idList
     */
    int batchDelete(List<Integer> idList);
}

测试结果

public class TestUserMapper {

    SqlSessionFactory sqlSessionFactory = null;
    SqlSession sqlSession = null;
    UserMapper userMapper = null;

    @Before
    public void before(){
        // mybatis 配置文件地址
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 加载配置文件，并构建sqlSessionFactory
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 获取sqlSession对象
        sqlSession = sqlSessionFactory.openSession();
        userMapper = sqlSession.getMapper(UserMapper.class);
    }

    @After
    public void after(){
        if(sqlSession != null){
            // 注意这里的commit，否则提交不成功
            sqlSession.commit();
            sqlSession.close();
        }
    }

    /**
     * 测试批量保存
     */
    @org.junit.Test
    public void testBatchSave(){
        List<User> userList = new ArrayList();
        userList.add(new User("张飞", 55));
        userList.add(new User("关羽", 60));

        int c = userMapper.batchSave(userList);
        System.out.println("新增数量：" + c);
        for (User user : userList) {
            System.out.println(user);
        }
    }

    /**
     * 测试批量删除
     */
    @org.junit.Test
    public void testBatchDelete(){
        List<Integer> idList = new ArrayList();
        idList.add(13);
        idList.add(14);

        int c = userMapper.batchDelete(idList);
        System.out.println("删除数量为："+c);

    }

}

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