mybatis02-mybatis的CRUD

1. 查询

• 查询所有
• mapper类

public interface UserMapper {

    //查询所有
     List<User> findAll();
}

• 映射xml

<mapper namespace="com.zzl.mapper.UserMapper">

   <select id="findAll" resultType="com.zzl.pojo.User">
       select * from user;
   </select>

</mapper>

• 测试类Test

public class UserMapperTest {

    //查询所有
    @Test
    public void findAll() {
        //1.获取SqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        //2.执行sql
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList=userMapper.findAll();

        for (User user:userList){
            System.out.println(user);
        }

        //关闭
        sqlSession.close();
    }
}

2. 增加

• mapper类

Integer addUser(User user);

• 映射xml

    <select id="addUser" resultType="com.zzl.pojo.User">
        insert into user(useid,usename,password) values(#{useid},#{usename},#{password});
    </select>

• 测试类Test

    //增加一个用户
    @Test
    public void addUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);

        userMapper.addUser(new User(5,"haha","123"));

        //增删改要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

3. 修改

• mapper类
  Integer updateUser(User user);
• 映射xml

    <update id="updateUser" >
        update user set usename = #{usename},password=#{password} where useid=#{useid};
    </update>

• 测试类Test

    //修改一个用户
    @Test
    public void updateUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);

        userMapper.updateUser(new User(4,"hehe","1231"));

        //增删改要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

4. 删除

• mapper类

    //删除用户
    Integer deleteUser(int id);

• 映射xml

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

• 测试类Test

    //删除一个用户
    @Test
    public void deleteUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);

        userMapper.deleteUser(4);

        //增删改要提交事务
        sqlSession.commit();
        sqlSession.close();
    }