为什么[import java.awt。*]不包含[import java.awt.event.ActionEvent]？(Why does [import java.awt.*] not also include [import java.awt.event.ActionEvent]?)

 这是您如何使用MemoryStream创建新的电子表格文档，然后将其保存为Byte[] 
 
Byte[] file;
using (MemoryStream mem = new MemoryStream())
{
    using (SpreadsheetDocument spreadsheetDocument = 
        SpreadsheetDocument.Create(mem, SpreadsheetDocumentType.Workbook))
    {
        WorkbookPart workbookpart = spreadsheetDocument.AddWorkbookPart();
        workbookpart.Workbook = new Workbook();
        WorksheetPart worksheetPart = workbookpart.AddNewPart<WorksheetPart>();
        worksheetPart.Worksheet = new Worksheet(new SheetData());

        Sheets sheets = spreadsheetDocument.WorkbookPart.Workbook.
            AppendChild<Sheets>(new Sheets());

        Sheet sheet = new Sheet()
        {
            Id = spreadsheetDocument.WorkbookPart.
                GetIdOfPart(worksheetPart),
            SheetId = 1,
            Name = "aStupidSheet"
        };
        sheets.Append(sheet);
        workbookpart.Workbook.Save()
        spreadsheetDocument.Close();
    }
    file = mem.ToArray();
}

With the help from FortyTwo I managed to achieve my goal.
 
So the desired "workflow" is:
 
 
 
copy .docx template (added headers or other things) to memory
 
 
edit content of the document
 
 
return this document as FileResult without saving the changes to template
 
 
So here is the code:
 
public FileResult EditDOCXBody()
{
    // Prepare file path
    string file = "../WordTemplates/EmptyTemplate.docx";
    String fullFilePath = HttpContext.ApplicationInstance.Server.MapPath(file);                   

    // Copy file content to MemeoryStream via byte array
    MemoryStream stream = new MemoryStream();                          
    byte[] fileBytesArray = System.IO.File.ReadAllBytes(fullFilePath);  
    stream.Write(fileBytesArray, 0, fileBytesArray.Length);             // copy file content to MemoryStream
    stream.Position = 0;                                                

    // Edit word document content
    using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(stream, true))  
    {
        MainDocumentPart mainPart = wordDoc.MainDocumentPart;                
        Body body = mainPart.Document.Body;

        // add some text to body
        body.Append(new Paragraph(
                    new Run(
                        new Text("Current time is: " + DateTime.Now.ToLongTimeString()))));

        // Save changes to reflect on stream object
        mainPart.Document.Save();                
    }
    return File(stream.ToArray(), "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "servedFilename.docx");            
}
 
Some important notes:
 
 
 
you need to write file bytes to MemoryStream manually otherwise you get Memory stream is not expandable error. More info here
 
 
you have to use mainPart.Document.Save() for changes to take effect on MemoryStream
 
 
when returning the file, you have to use .ToArray() otherwise the returned file is corrupted