c# - File.WriteAllLines 似乎没有关闭

Question

我正在尝试向网站添加一项功能，该功能会将 outlook 邀请附件发送到电子邮件。一切都在第一次完美运行，但再次运行后，我收到以下错误:“该进程无法访问文件‘OutlookCalendar.ics’，因为它正被另一个进程使用。”我已经到处寻找答案，但似乎当我使用 file.WriteAllLines 时，它不会关闭文件？请参阅下面的代码...

     //CREATE OUTLOOK ATTACHMENT.....................................................................................................
        //..............................................................................................................................
        string schLocation = "Kettle Cuisine TBD";
        string schSubject = visitor + " is visiting.";
        string schDescription = other;
        System.DateTime schBeginDate = Convert.ToDateTime(date + " " + time);
        System.DateTime schEndDate = Convert.ToDateTime(date + " 17:00");

        //PUTTING THE MEETING DETAILS INTO AN ARRAY OF STRING

        String[] contents = { "BEGIN:VCALENDAR",
                          "PRODID:-//Flo Inc.//FloSoft//EN",
                          "BEGIN:VEVENT",
                          "DTSTART:" + schBeginDate.ToUniversalTime().ToString("yyyyMMdd\\THHmmss\\Z"), 
                          "DTEND:" + schEndDate.ToUniversalTime().ToString("yyyyMMdd\\THHmmss\\Z"), 
                          "LOCATION:" + schLocation, 
                     "DESCRIPTION;ENCODING=QUOTED-PRINTABLE:" + schDescription,
                          "SUMMARY:" + schSubject, "PRIORITY:3", 
                     "END:VEVENT", "END:VCALENDAR" };

        /*THE METHOD 'WriteAllLines' CREATES A FILE IN THE SPECIFIED PATH WITH 
       THE SPECIFIED NAME,WRITES THE ARRAY OF CONTENTS INTO THE FILE AND CLOSES THE
        FILE.SUPPOSE THE FILE ALREADY EXISTS IN THE SPECIFIED LOCATION,THE CONTENTS 
       IN THE FILE ARE OVERWRITTEN*/

        System.IO.File.WriteAllLines(Server.MapPath("OutlookCalendar.ics"), contents);

        //END CREATE OUTLOOK ATTACHMENT.....................................................................................................
        //..............................................................................................................................


        //Send out email
        Email.sendEmailOutlook(message, email, header);

在电子邮件部分我使用这个.... //从创建的 .ICS 文件中创建附件

        Attachment mailAttachment = new Attachment(System.Web.HttpContext.Current.Server.MapPath("OutlookCalendar.ics"));
        mail.Attachments.Add(mailAttachment);

        mail.IsBodyHtml = true;
        //Set email message and subjet
        mail.Subject = header;
        mail.Body = message;

        smtpClient.Send(mail);

Answer 1

我怀疑问题不在于 File.WriteAllLines，而在于 Attachment - 实现了 IDisposable，但你没有处理它的......所以如果它有一个打开的文件句柄，那将解释你所看到的。你可以只使用:

var path = HttpContext.Current.Server.MapPath("OutlookCalendar.ics");
using (Attachment mailAttachment = new Attachment(path))
{
    mail.Attachments.Add(mailAttachment);

    mail.IsBodyHtml = true;
    //Set email message and subjet
    mail.Subject = header;
    mail.Body = message;

    smtpClient.Send(mail);
}

但是，根本不清楚为什么需要写入文件。最好将您的代码更改为仅创建一个 MemoryStream。例如:

string text = string.Join("\r\n", contents);
byte[] encoded = Encoding.UTF8.GetBytes(text);
var stream = new MemoryStream(encoded);
using (var attachment = new Attachment(stream, "OutlookCalendar.ics"))
{
    ...
}

现在根本不涉及任何文件，所以不会有任何冲突。