NET Excel转换为集合对象

1.仅适用于规则Excel：表头和数据一一对应

2.涉及到Excel转换为集合对象的部分代码，完整npoi帮助类点击查看

        /// <summary>
        /// 默认把excel第一个sheet中的数据转换为对象集合
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="entity"></param>
        /// <param name="filePath">文件路径</param>
        /// <param name="sheetIndex">数据所在sheet索引：默认第一个sheet</param>
        /// <param name="originIndex">数据开始行：表头行索引</param>
        /// <returns></returns>
        public static List<T> ConvertExcelToList<T>(T entity, string filePath, int sheetIndex = 0, int originIndex = 0)
            where T : class, new()
        {
            var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
            using (stream)
            {
                return ConvertExcelToList(entity, filePath, stream, sheetIndex, originIndex);
            }

        }

        /// <summary>
        /// 把excel转换为对象集合
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="entity"></param>
        /// <param name="filePath">文件路径</param>
        /// <param name="stream">文件流</param>
        /// <param name="sheetIndex">数据所在sheet索引：默认第一个sheet</param>
        /// <param name="originIndex">数据开始行：表头行索引</param>
        /// <returns></returns>
        public static List<T> ConvertExcelToList<T>(T entity, string filePath, Stream stream, int sheetIndex = 0, int originIndex = 0)
            where T : class, new()
        {
            //  结果集合
            var list = new List<T>();

            //  获取特性和属性的关系字典
            Dictionary<string, string> propertyDictionary = GetPropertyDictionary(entity);

            var isExcel2007 = filePath.IsExcel2007();
            var workBook = stream.GetWorkbook(isExcel2007);
            //  获得数据所在sheet对象
            var sheet = workBook.GetSheetAt(sheetIndex);
            //  获取表头和所在索引的关系字典
            Dictionary<string, int> headerDictionary = GetHeaderDictionary(originIndex, propertyDictionary, sheet);

            //  两个字典对象，只有一个为空，则return
            if (!propertyDictionary.Any() || !headerDictionary.Any())
            {
                return list;
            }

            //  生成结果集合
            BuilderResultList(originIndex, list, propertyDictionary, sheet, headerDictionary);
            return list;
        }

        /// <summary>
        /// 生成结果集合
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="originIndex">数据开始行：表头行索引</param>
        /// <param name="list">结果集合</param>
        /// <param name="propertyDictionary">特性和属性的关系字典:属性字典</param>
        /// <param name="sheet">数据所在sheet对象</param>
        /// <param name="headerDictionary">表头和所在索引的关系字典:表头字典</param>
        private static void BuilderResultList<T>(int originIndex, List<T> list, Dictionary<string, string> propertyDictionary, ISheet sheet, Dictionary<string, int> headerDictionary) where T : class, new()
        {
            #region 通过反射，绑定参数

            //  从表头行下一行开始循环，直到最后一行
            for (int rowIndex = originIndex + 1; rowIndex <= sheet.LastRowNum; rowIndex++)
            {
                T newEntity = new T();
                var newEntityType = newEntity.GetType();
                var itemRow = sheet.GetRow(rowIndex);

                //  循环表头字典
                foreach (var itemKey in headerDictionary.Keys)
                {
                    //  得到先对应的表头列所在列索引
                    var columnIndex = headerDictionary[itemKey];
                    //  把格式转换为utf-8
                    var itemCellValue = itemRow.GetValue(columnIndex).FormatUtf8String();

                    //  根据表头值，从 属性字典 中获得 属性值 名
                    var propertyName = propertyDictionary[itemKey];
                    newEntityType.GetProperty(propertyName).SetValue(newEntity, itemCellValue);
                }
                list.Add(newEntity);
            }

            #endregion
        }

        /// <summary>
        /// 获取表头和所在索引的关系字典
        /// </summary>
        /// <param name="originIndex">数据开始行：表头行索引</param>
        /// <param name="propertyDictionary">特性和属性的关系字典:属性字典</param>
        /// <param name="sheet">数据所在sheet对象</param>
        /// <returns></returns>
        private static Dictionary<string, int> GetHeaderDictionary(int originIndex, Dictionary<string, string> propertyDictionary, ISheet sheet)
        {
            var headerDictionary = new Dictionary<string, int>();

            #region 获取表头和所在索引的关系字典

            //  获得表头所在row对象
           var itemRow = sheet.GetRow(originIndex);
            //  记录表头行，表头和所在索引的关系，存入字典，暂不考虑表头相同情况
            headerDictionary = new Dictionary<string, int>();
            //  可能会存在无限列情况，设置最大列为200
            var cellTotal = itemRow.Cells.Count() > 200 ? 200 : itemRow.Cells.Count();
            for (int columnIndex = 0; columnIndex < cellTotal; columnIndex++)
            {
                //  把格式转换为utf-8
                var itemCellValue = itemRow.GetValue(columnIndex).FormatUtf8String();
                //  itemCellValue补等于空 且 不在headerDictionary中 且 在propertyDictionary中
                if (!itemCellValue.IsNullOrWhiteSpace() && !headerDictionary.ContainsKey(itemCellValue) && propertyDictionary.ContainsKey(itemCellValue))
                {
                    headerDictionary.Add(itemCellValue, columnIndex);
                }
            }

            #endregion

            return headerDictionary;
        }

        /// <summary>
        /// 获取特性和属性的关系字典
        /// </summary>
        /// <param name="PropertyArr"></param>
        /// <returns></returns>
        private static Dictionary<string, string> GetPropertyDictionary<T>(T entity)
        {
            //  获取type
            var userType = typeof(T);
            //  获取类中所有公共属性集合
            var propertyArr = userType.GetProperties();

            #region 获取特性和属性的关系字典

            //  属性字典，保存别名和属性的对应关系
            //  key：别名，特性中的值
            //  value：属性名，类中的属性
            var propertyDictionary = new Dictionary<string, string>();
            foreach (var itemProperty in propertyArr)
            {
                //  获取属性上存在AliasAttribute的数组
                var customAttributesArr = itemProperty.GetCustomAttributes(typeof(AliasAttribute), true);
                //  存在该特性
                if (customAttributesArr.Any())
                {
                    var first = (AliasAttribute)customAttributesArr.FirstOrDefault();
                    if (!propertyDictionary.ContainsKey(first.Name))
                    {
                        propertyDictionary.Add(first.Name, itemProperty.Name);
                    }
                }
            }

            #endregion
            return propertyDictionary;
        }

3.调用测试

            var path = @"C:\导入文件.xlsx";
            var result = NpoiHelper.ConvertExcelToList(new UserDto(), path);

            Assert.IsTrue(result.Any());