如何让 File.Delete() 实际删除我的文件？

Question

我生成一个PDF文件，保存在服务器上：

var bytes = ms.ToArray();
. . .
String fileFullpath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory), pdfFileName);
. . .
File.WriteAllBytes(fileFullpath, bytes);

...然后将其保存到 Sharepoint 文档库中，并将其作为电子邮件附件发送给生成文件的人：

SavePDFToDocumentLibrary(fileFullpath);
String from = GetFromEmailID();
String to = GetUserEmail();
String subjLine = String.Format("The PDF file you generated ({0})", pdfFileName);
String body = String.Format("The Direct Pay PDF file you generated ({0}) is attached.", pdfFileName);
SendEmailWithAttachment(fileFullpath, from, to, subjLine, body);
// Now that it has been put in a Document Library and emailed, delete the file that was saved locally
File.Delete(fileFullpath);

...此时，我不再需要我保存到服务器磁盘上的文件，因此，如上面最后一行所示，尝试删除它。

但是，它不起作用。现在冗余的文件仍在保存位置。

为什么，我怎样才能让它理解“删除”真的意味着“删除”？

更新

以下是 Scott 希望看到的方法：

// This works; got it from Henry Zucchini's answer at http://stackoverflow.com/questions/468469/how-do-you-upload-a-file-to-a-document-library-in-sharepoint
private void SavePDFToDocumentLibrary(String fullpath)
{
    String fileToUpload = fullpath;
    String sharePointSite = siteUrl;
    String documentLibraryName = "DirectPayPDFForms";

    using (SPSite oSite = new SPSite(sharePointSite))
    {
        using (SPWeb oWeb = oSite.OpenWeb())
        {
            if (!System.IO.File.Exists(fileToUpload))
                throw new FileNotFoundException("File not found.", fileToUpload);

            SPFolder doclib = oWeb.Folders[documentLibraryName];

            // Prepare to upload
            Boolean replaceExistingFiles = true;
            String fileName = System.IO.Path.GetFileName(fileToUpload);
            FileStream fileStream = File.OpenRead(fileToUpload);

            // Upload document
            SPFile spfile = doclib.Files.Add(fileName, fileStream, replaceExistingFiles);

            // Commit 
            doclib.Update();
        }
    }
}

// This is adapted from https://msdn.microsoft.com/en-us/library/system.net.mail.mailmessage(v=vs.90).aspx
public static void SendEmailWithAttachment(string fileToMail, String from, String to, String subj, String body)
{
    String server = GetSMTPHostName(); //"468802-DEV-SPWF"; // change this to prod when go live, or programatically assign?
    // Specify the file to be attached and sent. 
    string file = fileToMail;
    // Create a message and set up the recipients.
    MailMessage message = new MailMessage(
       from,
       to,
       subj,
       body);

    // Create  the file attachment for this e-mail message.
    Attachment data = new Attachment(file, MediaTypeNames.Application.Octet);
    // Add time stamp information for the file.
    ContentDisposition disposition = data.ContentDisposition;
    disposition.CreationDate = System.IO.File.GetCreationTime(file);
    disposition.ModificationDate = System.IO.File.GetLastWriteTime(file);
    disposition.ReadDate = System.IO.File.GetLastAccessTime(file);
    // Add the file attachment to this e-mail message.
    message.Attachments.Add(data);

    //Send the message.
    SmtpClient client = new SmtpClient(server);
    // Add credentials if the SMTP server requires them.
    client.Credentials = CredentialCache.DefaultNetworkCredentials;

    try
    {
        client.Send(message);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Exception caught in CreateMessageWithAttachment(): {0}", ex.ToString());
    }
    // Display the values in the ContentDisposition for the attachment.
    // May not need/want this section
    ContentDisposition cd = data.ContentDisposition;
    Console.WriteLine("Content disposition");
    Console.WriteLine(cd.ToString());
    Console.WriteLine("File {0}", cd.FileName);
    Console.WriteLine("Size {0}", cd.Size);
    Console.WriteLine("Creation {0}", cd.CreationDate);
    Console.WriteLine("Modification {0}", cd.ModificationDate);
    Console.WriteLine("Read {0}", cd.ReadDate);
    Console.WriteLine("Inline {0}", cd.Inline);
    Console.WriteLine("Parameters: {0}", cd.Parameters.Count);
    foreach (DictionaryEntry d in cd.Parameters)
    {
        Console.WriteLine("{0} = {1}", d.Key, d.Value);
    }
    // </ May not need/want this section
    data.Dispose();
}

更新 2

我在单步执行时看到，添加此测试后：

if (File.Exists(fileFullpath))
{
    File.Delete(fileFullpath);
}

...毕竟在 IOException 捕获块中有 一个异常：

进程无法访问文件“C:\Users\TEMP.SP.018\Desktop\DirectPayDynamic_2015Jul28_19_02_clayshan_0.pdf”，因为它正被另一个进程使用。

那么其他方法之一是如何坚持下去的呢？ ISTM 认为 SavePDFToDocumentLibrary() 是安全的，因为它使用 using 块。

是 data.Dispose();在 SendEmailWithAttachment() 中还不够吗？我需要在那里显式调用 close 吗？

更新 3

我添加了“message.Dispose();”就在“data.Dispose();”之前在 SendEmailWithAttachment() 中，但没有区别。

Answer 1

尝试像这样处理SavePDFToDocumentLibrary中使用的文件流：

using (FileStream fileStream = File.OpenRead(fileToUpload))
{
    ...
}