npoi导入导出excel (泛型)

　　最近新项目开始了，万能的excel又要上台工作。对于导出代码网上的确很多，合适的没有找到。

　　我们这边使用的ef + dapper 两套orm框架，他们有一个共同点，都是操作实体对象的。所以导出不能用万能的DataTable了。后面花了一些时间，集合众仙所长，写了一套单excel导入导出的方式。数据源为List<T>

　　

  public class Excel
    {

        /// <summary>
        /// 导出到sheet中
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="path"></param>
        /// <param name="list"></param>
        /// <param name="sheetName"></param>
        public static void Export<T>(string path, List<T> list, string sheetName = "sheet1") where T : class, new()
        {
            IWorkbook book = null;

            //this.gridView1.ExportToXls(sflg.FileName);
            //NPOI.xs book = new NPOI.HSSF.UserModel.HSSFWorkbook();
            if (Path.GetExtension(path).ToLower() != ".xlsx")
            {
                book = new HSSFWorkbook();
            }
            else
            {
                book = new XSSFWorkbook();//07
            }

            ISheet sheet = book.CreateSheet("sheet");

            // 添加表头
            var pros = typeof(T).GetProperties();
            IRow row = sheet.CreateRow(0);
            int index = 0;


            foreach (var p in pros)
            {
                string alias = AliasAttribute<T>(p);
                if (!string.IsNullOrEmpty(alias))
                {
                    ICell cell = row.CreateCell(index);
                    cell.SetCellType(CellType.String);
                    cell.SetCellValue(alias);
                    int num = Encoding.GetEncoding(936).GetBytes(alias).Length;

                    sheet.SetColumnWidth(index, num * 500);

                    index++;
                }
            }



            // 添加数据
            for (int i = 0; i < list.Count; i++)
            {
                index = 0;
                row = sheet.CreateRow(i + 1);
                foreach (var p in pros)
                {
                    string alias = AliasAttribute<T>(p);
                    if (!string.IsNullOrEmpty(alias))
                    {
                        //var attributes = p.GetCustomAttributes(typeof(AliasAttribute), false);
                        //var type = (AliasAttribute)attributes[0];
                        object value = p.GetValue(list[i], null);

                        ICell cell = row.CreateCell(index);
                        //cell.SetCellType(CellType.String);
                        //cell.SetCellValue(value);

                        SetCellValue(cell, p, value, book);
                        index++;
                    }
                }
            }

            // 写入 
            MemoryStream ms = new MemoryStream();
            book.Write(ms);

            using (FileStream fs = new FileStream(path, FileMode.Create, FileAccess.Write))
            {
                byte[] data = ms.ToArray();
                fs.Write(data, 0, data.Length);
                fs.Flush();
            }

            ms.Close();
            ms.Dispose();

        }

        private static string AliasAttribute<T>(PropertyInfo p) where T : class, new()
        {
            var attributes = p.GetCustomAttributes(typeof(AliasAttribute), false);
            AliasAttribute type = null;
            foreach (var o in attributes)
            {
                if (o is AliasAttribute)
                {
                    type = o as AliasAttribute;
                }
            }
            return type?.Alias;
        }

        /// <summary>
        /// 读Excel单元格的数据
        /// </summary>
        /// <param name="cell">Excel单元格</param>
        /// <param name="type">列数据类型</param>
        /// <param name="value"></param>
        /// <param name="book"></param>
        /// <returns>object 单元格数据</returns>
        private static void SetCellValue(ICell cell, PropertyInfo type, object value, IWorkbook book)
        {
            string dataType = type.PropertyType.FullName;

            switch (dataType)
            {
                case "System.String"://字符串类型

                    cell.SetCellValue(Convert.ToString(value));
                    break;
                case "System.DateTime"://日期类型

                    ICellStyle cellDateStyle = book.CreateCellStyle();
                    IDataFormat format = book.CreateDataFormat();
                    cellDateStyle.DataFormat = format.GetFormat("yyyy-MM-dd hh:mm:ss");//yyyy-mm-dd hh:mm:ss
                    cell.CellStyle = cellDateStyle;

                    cell.SetCellValue(Convert.ToDateTime(value));
                    break;
                case "System.Boolean"://布尔型
                    cell.SetCellValue(Convert.ToBoolean(value));
                    break;
                case "System.Int16"://整型
                case "System.Int32":
                case "System.Int64":
                case "System.Byte":
                    cell.SetCellValue(Convert.ToUInt64(value));
                    break;
                case "System.Decimal"://浮点型
                case "System.Double":
                    cell.SetCellValue(Convert.ToDouble(value));
                    break;
                case "System.DBNull"://空值处理
                    cell.SetCellValue("");
                    break;
                default:
                    throw (new Exception(dataType + "：类型数据无法处理!"));
            }


        }

        /// <summary>
        /// 导入
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="path"></param>
        /// <param name="sheetIndex"></param>
        /// <returns></returns>
        public static List<T> Import<T>(string path, int sheetIndex = 0) where T : class, new()
        {

            List<T> list = new List<T>();
            IWorkbook book;
            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
            if (Path.GetExtension(path).ToLower() != ".xlsx")
            {
                book = new HSSFWorkbook(fs);
            }
            else
            {
                book = new XSSFWorkbook(fs);//07
            }

            ISheet sheet = book.GetSheetAt(sheetIndex);

            IRow row = sheet.GetRow(0);
            if (row == null)
                return list;

            int firstCellNum = row.FirstCellNum;
            int lastCellNum = row.LastCellNum;

            if (firstCellNum == lastCellNum)
                return list;


            //记录列号与属性名称对应关系 
            Dictionary<int, PropertyInfo> dictionary = new Dictionary<int, PropertyInfo>();
            var pros = typeof(T).GetProperties();
            for (int i = firstCellNum; i < lastCellNum; i++)
            {
                string name = row.GetCell(i).StringCellValue;
                foreach (var p in pros)
                {
                    string alias = AliasAttribute<T>(p);
                    if ((!string.IsNullOrEmpty(alias)) && name == alias)
                    {
                        dictionary.Add(i, p);
                        break;
                    }
                }
            }

            for (int i = 1; i <= sheet.LastRowNum; i++)
            {
                T t = new T();
                row = sheet.GetRow(i);
                //for (int j = firstCellNum; j < lastCellNum; j++)

                foreach (var info in dictionary)
                {
                    SetValue(row.GetCell(info.Key), info.Value, t);
                }


                list.Add(t);
            }

            return list;

        }

        /// <summary>
        /// 读Excel单元格的数据
        /// </summary>
        /// <param name="cell">Excel单元格</param>
        /// <param name="type">列数据类型</param>
        /// <param name="obj"></param>
        /// <returns>object 单元格数据</returns>
        private static void SetValue(ICell cell, PropertyInfo type, object obj)
        {

            object cellValue;
            switch (cell.CellType)
            {
                case CellType.String: //文本
                    cellValue = cell.StringCellValue;
                    break;
                case CellType.Numeric: //数值
                    if (cell.CellType == CellType.Numeric && DateUtil.IsCellDateFormatted(cell))
                    {
                        cellValue = cell.DateCellValue;
                        break;
                    }
                    cellValue = cell.NumericCellValue;
                    break;
                case CellType.Boolean: //bool
                    cellValue = cell.BooleanCellValue;
                    break;
                case CellType.Blank: //空白
                    cellValue = "";
                    break;
                default:
                    cellValue = null;
                    break;
            }

            string dataType = type.PropertyType.FullName;

            if (dataType == "System.String")
            {
                type.SetValue(obj, cellValue, null);
            }
            else if (dataType == "System.DateTime")
            {
                DateTime pdt = Convert.ToDateTime(cellValue);
                type.SetValue(obj, pdt, null);
            }
            else if (dataType == "System.Boolean")
            {
                bool pb = Convert.ToBoolean(cellValue);
                type.SetValue(obj, pb, null);
            }
            else if (dataType == "System.Int16")
            {
                Int16 pi16 = Convert.ToInt16(cellValue);
                type.SetValue(obj, pi16, null);
            }
            else if (dataType == "System.Int32")
            {
                Int32 pi32 = Convert.ToInt32(cellValue);
                type.SetValue(obj, pi32, null);
            }
            else if (dataType == "System.Int64")
            {
                Int64 pi64 = Convert.ToInt64(cellValue);
                type.SetValue(obj, pi64, null);
            }
            else if (dataType == "System.Byte")
            {
                Byte pb = Convert.ToByte(cellValue);
                type.SetValue(obj, pb, null);
            }
            else if (dataType == "System.Decimal")
            {
                System.Decimal pd = Convert.ToDecimal(cellValue);
                type.SetValue(obj, pd, null);
            }
            else if (dataType == "System.Double")
            {
                double pd = Convert.ToDouble(cellValue);
                type.SetValue(obj, pd, null);
            }
            else
            {
                type.SetValue(obj, null, null);
            }

        }
    }

　　

　　导出的中文名称是一个大问题，总不能把实体中的属性导出到excel中，定义中文属性又不符合”我们“的风格。没有无法解决的问题，我们用特性，看我们的大招

    /// <summary>
    /// 导出excel列名
    /// </summary>
    [AttributeUsage(AttributeTargets.Property)]
    public class AliasAttribute : Attribute
    {
        /// <summary>
        /// 属性别名
        /// </summary>
        public string Alias { get; }

        /// <summary>
        /// 构造方法
        /// </summary>
        /// <param name="alias">别名</param>
        public AliasAttribute(string alias)
        {
            Alias = alias;
        }
    }

　　

代码写完了，后面简单测试一下。

    [TestClass]
    public class ExcelTest
    {
        /// <summary>
        /// 导出
        /// </summary>
        [TestMethod]
        public void Export()
        {
            List<ExcelTestM> listExcelTestMs = new List<ExcelTestM>(100);
            for (int i = 0; i < 100; i++)
            {
                listExcelTestMs.Add(new ExcelTestM()
                {
                    Name = "张三" + i,
                    Age = i,
                    Address = "确认ws能够成功建立连接。如果ws无法正常建立连接，请参照",
                    CreateDate = DateTime.Now,
                    Ishides = true,
                    Amount = i / 1.1,
                });
            }

            Excel.Export(@"D:1.xlsx", listExcelTestMs);

        }

        /// <summary>
        /// 实体中只有部分列导出
        /// 如果：只导出配置的列
        /// </summary>
        [TestMethod]
        public void ExportPart()
        {
            List<ExcelTestM> listExcelTestMs = new List<ExcelTestM>(100);
            for (int i = 0; i < 100; i++)
            {
                listExcelTestMs.Add(new ExcelTestM()
                {
                    Name = "张三" + i,
                    Age = i,
                    Address = "确认ws能够成功建立连接。如果ws无法正常建立连接，请参照",
                    CreateDate = DateTime.Now,
                    Ishides = true,
                    Amount = i / 1.1,
                });
            }

            Excel.Export(@"D:1.xlsx", listExcelTestMs);
        }


        /// <summary>
        /// 导入
        /// </summary>
        [TestMethod]
        public void Import()
        {
            var list = Excel.Import<ExcelTestM>(@"D:1.xlsx");

        }

        /// <summary>
        /// 导入
        /// 1、EXCEL列多于实体
        /// 2、实体列多于EXCEL
        /// 结果：取实体与EXCEL的交集
        /// </summary>
        [TestMethod]
        public void ImportPart()
        {
            //1、EXCEL列多于实体
            var list = Excel.Import<ExcelTestM>(@"D:1.xlsx");


            //2、实体列多于EXCEL
            list = Excel.Import<ExcelTestM>(@"D:1.xlsx");
        }




    }

    /// <summary>
    /// excel测试实体
    /// </summary>
    public class ExcelTestM
    {
        /// <summary>
        /// 姓名
        /// </summary>
        [Alias("姓名")]
        public string Name { get; set; }

        /// <summary>
        /// 年龄
        /// </summary>
        [Alias("年龄")]
        public int Age { get; set; }

        /// <summary>
        /// 地址
        /// </summary>
        [Alias("地址1111111111111111")]
        public string Address { get; set; }


        [Alias("日期")]
        public DateTime CreateDate { get; set; }


        public bool Ishides { get; set; }

        //[Alias("数据啊啊啊")]
        public double Amount { get; set; }


    }

　　感谢你能耐心的看到最后，这些代码没有添加错误处理，你在使用时，可以直接获取到错误信息，以提示用户。