<select id="getById" parameterType="Long" resultType="dyyx.data.UserDO">
    SELECT * FROM t_user where id=#{id}
</select>
<select id="getById2" parameterType="Long" resultMap="UserDTO">
    SELECT * FROM t_user where id=#{id}
</select>



结果集两种映射方式  resultType resultMap
applyAutomaticMappings     根据 resultType 自动映射赋值
applyPropertyMappings      根据resultMap 配合赋值


org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(ResultSetWrapper, ResultMap, String)

private Object getRowValue(ResultSetWrapper rsw, ResultMap resultMap, String columnPrefix) throws SQLException {
    final ResultLoaderMap lazyLoader = new ResultLoaderMap();
    Object rowValue = createResultObject(rsw, resultMap, lazyLoader, columnPrefix);
    if (rowValue != null && !hasTypeHandlerForResultObject(rsw, resultMap.getType())) {
      final MetaObject metaObject = configuration.newMetaObject(rowValue);
      boolean foundValues = this.useConstructorMappings;
      if (shouldApplyAutomaticMappings(resultMap, false)) {
        foundValues = applyAutomaticMappings(rsw, resultMap, metaObject, columnPrefix) || foundValues;
      }
      foundValues = applyPropertyMappings(rsw, resultMap, metaObject, lazyLoader, columnPrefix) || foundValues;
      foundValues = lazyLoader.size() > 0 || foundValues;
      rowValue = foundValues || configuration.isReturnInstanceForEmptyRow() ? rowValue : null;
    }
    return rowValue;
}


例子代码
https://gitee.com/dyyx/demos/blob/master/mybatis/src/main/java/dyyx/MybatisTest.java

关于sql字段大小写
h2 取值时统一转成大写 ，不同的jdbc驱动实现可能不一样
org.h2.jdbc.JdbcResultSet

private Value get(String columnLabel) {
    return get(getColumnIndex(columnLabel));
}
Integer index = columnLabelMap.get(StringUtils.toUpperEnglish(columnLabel));
if (index == null) {
    throw DbException.get(ErrorCode.COLUMN_NOT_FOUND_1, columnLabel);
}
return index + 1;


TreeMap key 忽略大小写

            
              

 mybatis独立使用(不依赖spring)   
 MySQL jdbc ResultSet