.NET NPOI导出Excel详解

http://www.cnblogs.com/yinrq/p/5590970.html

.NET NPOI导出Excel详解

 

NPOI，顾名思义，就是POI的.NET版本。那POI又是什么呢？POI是一套用Java写成的库，能够帮助开发者在没有安装微软Office的情况下读写Office的文件。

支持的文件格式包括xls, doc, ppt等。

官方网站：http://npoi.codeplex.com/

nuget直接获取使用

一、NPOI生成Excel

            //创建工作薄
            var workbook = new HSSFWorkbook();
            //创建表
            var table = workbook.CreateSheet("joye.net");

            //模拟20行20列数据
            for (var i = 0; i < 20; i++)
            {
                var row = table.CreateRow(i);
                for (int j = 0; j < 20; j++)
                {
                    var cell = row.CreateCell(j);
                    cell.SetCellValue(j);
                }
            }
            //打开xls文件，如没有则创建，如存在则在创建是不要打开该文件
            using (var fs = File.OpenWrite(@"c:/joye.net.xls"))
            {
                workbook.Write(fs);   //向打开的这个xls文件中写入mySheet表并保存。
                Console.WriteLine("生成成功");
            }

二、NPOI读取Excel

using (var fs = File.OpenRead(@"c:/joye.net.xls")) 
            {
                //把xls文件中的数据写入workbook1中
                var workbook1 = new HSSFWorkbook(fs);
                for (var i = 0; i < workbook1.NumberOfSheets; i++)
                {
                    var sheet = workbook1.GetSheetAt(i);
                    for (var j = 0; j <= sheet.LastRowNum; j++)
                    {   
                        //读取当前行数据
                        var row = sheet.GetRow(j);
                        if (row != null)
                        {
                            for (var k = 0; k <= row.LastCellNum; k++)
                            {   //当前表格
                                var cell = row.GetCell(k);
                                if (cell != null)
                                {
                                    Console.Write(cell.ToString() + "  ");
                                }
                            }
                        }
                        Console.WriteLine();
                    }
                }
            }

读出的结果

 三、简单学习

 

 

四、NPOI导出Excel 65536问题

        public static HSSFWorkbook BuildWorkbook(DataTable dt)
        {
            var book = new HSSFWorkbook();  

            ISheet sheet = book.CreateSheet("Sheet1");
            //Data Rows
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                IRow drow = sheet.CreateRow(i);
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    ICell cell = drow.CreateCell(j, CellType.String);
                    cell.SetCellValue(dt.Rows[i][j].ToString());
                }
            }
            //自动列宽
            for (int i = 0; i <= dt.Columns.Count; i++)
                sheet.AutoSizeColumn(i, true);
            return book;
        }

NPOI导出Excel超过65536会报异常，原来是由于NPOI这个动态库导致的，然后看了下版本，发现是1.2.5。然后百度了下，发现这个版本的NPOI只支持office2003，二office2003最多支持65536行

解决方式：

1、只是在插入数据的时候，加个判断，如果数据条数大于65536时，就在创建一个sheet

        //65536判断处理
        public static HSSFWorkbook BuildWorkbook(DataTable dt)
        {
            var book = new HSSFWorkbook();

            ISheet sheet1 = book.CreateSheet("Sheet1");
            ISheet sheet2 = book.CreateSheet("Sheet2");

            //填充数据
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                if (i < 65536)
                {
                    IRow drow = sheet1.CreateRow(i);
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        ICell cell = drow.CreateCell(j, CellType.String);
                        cell.SetCellValue(dt.Rows[i][j].ToString());
                    }
                }
                if (i >= 65536)
                {
                    IRow drow = sheet2.CreateRow(i - 65536);
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        ICell cell = drow.CreateCell(j, CellType.String);
                        cell.SetCellValue(dt.Rows[i][j].ToString());
                    }
                }

            }

            //自动列宽
            for (int i = 0; i <= dt.Columns.Count; i++)
            {
                sheet1.AutoSizeColumn(i, true);
                sheet2.AutoSizeColumn(i, true);
            }
            return book;
        }

2、考虑使用高版本Office，使用用对象支持高版本的NPOI

        //高版本
        public static XSSFWorkbook BuildWorkbook(DataTable dt)
        {
            var book = new XSSFWorkbook();
            ISheet sheet = book.CreateSheet("Sheet1");
            //Data Rows
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                IRow drow = sheet.CreateRow(i);
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    ICell cell = drow.CreateCell(j, CellType.String);
                    cell.SetCellValue(dt.Rows[i][j].ToString());
                }
            }
            //自动列宽
            for (int i = 0; i <= dt.Columns.Count; i++)
                sheet.AutoSizeColumn(i, true);

            return book;
        }

五、web开发中导出Excel

        public static void ExportExcel(DataTable dt, string fileName = "")
        {
            //生成Excel
            IWorkbook book = BuildWorkbook(dt);

            //web 下载
            if (fileName == "")
                fileName = string.Format("{0:yyyyMMddHHmmssffff}", DateTime.Now);
            fileName = fileName.Trim();
            string ext = Path.GetExtension(fileName);

            if (ext.ToLower() == ".xls" || ext.ToLower() == ".xlsx")
                fileName = fileName.Replace(ext, string.Empty);

            HttpResponse httpResponse = HttpContext.Current.Response;
            httpResponse.Clear();
            httpResponse.Buffer = true;
            httpResponse.Charset = Encoding.UTF8.BodyName;
            httpResponse.AppendHeader("Content-Disposition", "attachment;filename=" + fileName + ".xls");
            httpResponse.ContentEncoding = Encoding.UTF8;
            httpResponse.ContentType = "application/vnd.ms-excel; charset=UTF-8";
            book.Write(httpResponse.OutputStream);
            httpResponse.End();
        }

基于.xls模板生成Excel文件有时间再看

代码下载：https://yunpan.cn/cRBVnTCSchz7k （提取码：779e） 

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