1.selectList（）返回值为List<resultType属性控制>

适用于查询结果都需要遍历的需求：

List<Flower> list = session.selectList(com.mapper.FlowerMapper.selAll);
        for(Flower flower :list) {
            System.out.println(flower.toString());
        }

2.selectOne（）返回值Object

适用于返回结果只是变量或一行数据时

int count = session.selectOne("com.mapper.FlowerMapper.selById");
        System.out.println(count);

3.selectMap（）返回值Map

适用于需要在查询结果中通过某列的值取到这行数据的需求

Map<key,resultType控制>

Map<Object, Object> map = session.selectMap("com.mapper.FlowerMapper.selMap", "name");
        System.out.println(map);

xml配置文档中对应代码

<select id="selAll" resultType="com.pojo.Flower">
          select * from flower
      </select>
      <select id="selById" resultType="int">
          select count(*) from flower
      </select>
      <select id="selMap" resultType="com.pojo.Flower">
          select * from flower
      </select>