NPOI導出Excel2007-xlsx

今天在用npoi導出xls時會報錯，經過在網上查找資料，找到一篇博客文章介紹的，原文地址
https://www.cnblogs.com/spring_wang/p/3160020.html

1.今天再處理Excel2007、2010文件，格式.xlsx文件存在一個問題,在調用 Write方法之后關閉了傳入的文件流。

 2.今天針對此問題好一頓的測試：

   2.1 在有文件構建時不是.xlsx文件格式會報錯，構建不成。.xls文件是不行的。

   2.2 XSSFWorkbook對象調用 write方法傳去MemoryStream對象后，會自動關閉傳入的參數。導致往Response.OutputStream會有問題？

      HSSFWorkbook對象則不會,針對這個問題還專門查了HSSFWorkbook源代碼下面有，本來想查XSSFWorkbook的源代碼，現在還沒公開呢。

 3.再有導出.xlsx文件時，在打開時總報：

     錯誤提示： Excel在“春天Excel2007.xlsx”中發現不可讀取內容。是否恢復工作簿的內容？如果信任此工作簿的來源，請單擊“是”。 單擊“是”后：Excel 已完成文件級驗證和修復。此工作簿的某些部分可能已被修復或丟棄。

那么這些問題如何處理呢？直接上代碼如下：

HSSFWorkbook類對象Write方法：

/// <summary>
        /// Write out this workbook to an Outputstream.  Constructs
        /// a new POI POIFSFileSystem, passes in the workbook binary representation  and
        /// Writes it out.
        /// </summary>
        /// <param name="stream">the java OutputStream you wish to Write the XLS to</param>
        public override void Write(Stream stream)
        {
            byte[] bytes = GetBytes();
            POIFSFileSystem fs = new POIFSFileSystem();
            // For tracking what we've written out, used if we're
            //  going to be preserving nodes
            List<string> excepts = new List<string>(1);

            MemoryStream newMemoryStream = new MemoryStream(bytes);
            // Write out the Workbook stream
            fs.CreateDocument(newMemoryStream, "Workbook");

            // Write out our HPFS properties, if we have them
            WriteProperties(fs, excepts);

            if (preserveNodes)
            {
                // Don't Write out the old Workbook, we'll be doing our new one
                excepts.Add("Workbook");
                // If the file had WORKBOOK instead of Workbook, we'll Write it
                //  out correctly shortly, so don't include the old one
                excepts.Add("WORKBOOK");

                // Copy over all the other nodes to our new poifs
                CopyNodes(this.filesystem, fs, excepts);
            }
            fs.WriteFileSystem(stream);

            fs.Dispose();
            newMemoryStream.Dispose();
            bytes = null;
        }

問題2對應代碼：

FileStream fileStream = new FileStream(HttpContext.Current.Server.MapPath("~/Resources/Template/" + strHeaderText  + ".xlsx"), FileMode.Create, FileAccess.Write);

                workbook.Write(fileStream);//調用這個后會關於文件流，在HSSFWorkbook不會關閉所以在處理時應注意
                FileStream fs = new FileStream(HttpContext.Current.Server.MapPath("~/Resources/Template/" + strHeaderText + ".xlsx"), FileMode.Open, FileAccess.Read);
                long fileSize = fs.Length;
byte[] fileBuffer = new byte[fileSize];

                fs.Read(fileBuffer, 0, (int)fileSize);
                HttpContext.Current.Response.BinaryWrite(fileBuffer);

                fs.Close();

問題3對應代碼：

FileStream fileStream = new FileStream(HttpContext.Current.Server.MapPath("~/Resources/Template/" + strHeaderText  + ".xlsx"), FileMode.Create, FileAccess.Write);

                workbook.Write(fileStream);//調用這個后會關於文件流，在HSSFWorkbook不會關閉所以在處理時應注意               
                FileStream fs = new FileStream(HttpContext.Current.Server.MapPath("~/Resources/Template/" + strHeaderText + ".xlsx"), FileMode.Open, FileAccess.Read);
                long fileSize = fs.Length;

　　　　　　　　   //加上設置大小下載下來的.xlsx文件打開時才沒有錯誤
                HttpContext.Current.Response.AddHeader("Content-Length", fileSize.ToString()); byte[] fileBuffer = new byte[fileSize];
                fs.Read(fileBuffer, 0, (int)fileSize);
                HttpContext.Current.Response.BinaryWrite(fileBuffer);

                fs.Close();

 結語：最后在本地正常，放服務器每次下載文件比實際要大，打開提示刪除不可見內容在最后加上一句正常

 context.Response.Flush();