如何通过电子邮件发送Excel文件？

Question

我有一个Excel文件(Excel 2003中/ XLS格式),我想通过电子邮件与C#来发送.我的代码成功发送,但是当我尝试打开响应文件时,它似乎编码错误.

例如,这里是响应文件名:

= _utf-8_B_RWxzesOhbW9sw6FzXzIwMTJfMTBfMTZf.dat

这是响应文件本身:

？= UTF-8乙VEdWdmJIWmhjMkZ1Wk1Pelh6UXlYekZmPz0NCiA9P3V0Zi04P0I/VGtW =\\ = UTF-8乙TlgwZFRXaTU0YkhNPT89 ="内容传输编码:？？？？？？？的base64 Content-Disposition的:附着

0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAABAAAA AQAAAAAAAAAAEAAAIwAAAAEAAAD + //// AAAAAAAAAAD ///////////////////// //////////////////// //////////////////////////////////////////// ////// //////////////////////// ....

这是我的代码片段:

...
var attachment = new Attachment(WriteFileToMemory("fileFullPath"), "fileName.xls");
attachment.ContentType = new ContentType("application/vnd.ms-excel");
attachmentCollection.Add(attachment);
...


private Stream WriteFileToMemory(string filePath)
{
    var memoryStream = new MemoryStream();
    _openedStreams.Add(memoryStream);
    using (var file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
    {
        var bytes = new byte[file.Length];
        file.Read(bytes, 0, (int) file.Length);
        memoryStream.Write(bytes, 0, (int) file.Length);
        file.Close();
    }
    memoryStream.Position = 0;
    return memoryStream;
}

如何设置附件编码类型,以及我应该使用哪些编码与Excel文件？

请帮我解决这个问题.提前致谢.

Answer 1

正如@Magnus指出的那样,你正在使它过于复杂,new Attachment()可以处理FileStreams,所以只需将新的文件流传递给构造函数即可.

...
var attachment = new Attachment(File.Open("fileFullPath", FileMode.Open), "fileName.xls");
attachment.ContentType = new ContentType("application/vnd.ms-excel");
attachmentCollection.Add(attachment);
...

虽然有点警告,但是有点偏离主题,你不能多次发送这样的邮件,因为流不会总是正确地重置自己.

Answer 2

如果您想从 DataTable 生成 Excel 并通过邮件发送，您可以按如下方式附加 Excel 文件：

Workbook theWorkbook = new Workbook();
theWorkbook.SetCurrentFormat(WorkbookFormat.Excel2007);
Worksheet theWorkSheet = theWorkbook.Worksheets.Add("Sheet1");

int iRow = 0;
int iColumn = 0;
theWorkSheet.Rows[0].CellFormat.Font.Bold = ExcelDefaultableBoolean.True;

//Titles
foreach (DataColumn column in DataTable.Columns)
{
    theWorkSheet.Rows[iRow].Cells[iColumn].Value = column.ColumnName;
    iColumn++;
}

//Values
foreach (DataRow row in DataTable.Rows)
{
    iColumn = 0;
    iRow++;

    foreach (var item in row.ItemArray)
    {
        theWorkSheet.Rows[iRow].Cells[iColumn].Value = item.ToString();
        iColumn++;
    }                    
}
System.IO.MemoryStream theStream = new System.IO.MemoryStream();
theWorkbook.Save(theStream);
byte[] byteArr = theStream.ToArray();
System.IO.MemoryStream stream1 = new System.IO.MemoryStream(byteArr, true);
stream1.Write(byteArr, 0, byteArr.Length);
stream1.Position = 0;
message.Attachments.Add(new Attachment(stream1, "filename.xlsx"));

它至少适用于 .NET framework 4 和 Excel 2016。

问候。

Answer 3

我找到了一个解决方案：

...
var attachment = CreateAttachment(WriteFileToMemory(Common.TempPath + excelName), excelName);
attachmentCollection.Add(attachment);
...

private Stream WriteFileToMemory(string filePath)
{
    var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
    _openedStreams.Add(fileStream);
    return fileStream;
}

public static Attachment CreateAttachment(Stream attachmentFile, string displayName)
{
    var attachment = new Attachment(attachmentFile, displayName);
    attachment.ContentType = new ContentType("application/vnd.ms-excel");
    attachment.TransferEncoding = TransferEncoding.Base64;
    attachment.NameEncoding = Encoding.UTF8;
    string encodedAttachmentName = Convert.ToBase64String(Encoding.UTF8.GetBytes(displayName));
    encodedAttachmentName = SplitEncodedAttachmentName(encodedAttachmentName);
    attachment.Name = encodedAttachmentName;
    return attachment;
}

private static string SplitEncodedAttachmentName(string encoded)
{
    const string encodingtoken = "=?UTF-8?B?";
    const string softbreak = "?=";
    const int maxChunkLength = 30;
    int splitLength = maxChunkLength - encodingtoken.Length - (softbreak.Length * 2);
    IEnumerable<string> parts = SplitByLength(encoded, splitLength);
    string encodedAttachmentName = encodingtoken;
    foreach (var part in parts)
    {
        encodedAttachmentName += part + softbreak + encodingtoken;
    }
    encodedAttachmentName = encodedAttachmentName.Remove(encodedAttachmentName.Length - encodingtoken.Length, encodingtoken.Length);
    return encodedAttachmentName;
}

private static IEnumerable<string> SplitByLength(string stringToSplit, int length)
{
    while (stringToSplit.Length > length)
    {
        yield return stringToSplit.Substring(0, length);
        stringToSplit = stringToSplit.Substring(length);
    }
    if (stringToSplit.Length > 0)
    {
        yield return stringToSplit;
    }
}

基于此来源： http://social.msdn.microsoft.com/Forums/en-US/dotnetframeworkde/thread/b6c764f7-4697-4394-b45f-128a24306d55