内存流不可扩展

Question

我正在尝试阅读电子邮件附件,并且我收到"内存流无法展开"错误.我研究了一些,大多数解决方案似乎与动态确定缓冲区的大小有关,但我已经这样做了.我对内存流不是很熟悉,所以我想知道为什么这是一个问题.谢谢.

foreach (MailMessage m in messages)
{
   byte[] myBuffer = null;
   if (m.Attachments.Count > 0)
   {
      //myBuffer = new byte[25 * 1024];  old way 
      myBuffer = new byte[m.Attachments[0].ContentStream.Length];
      int read;
      while ((read = m.Attachments[0].ContentStream.Read(myBuffer, 0, myBuffer.Length)) > 0)
      {
          // error occurs on executing next statement
          m.Attachments[0].ContentStream.Write(myBuffer, 0, read);
      }

      ... more unrelated code ...

Answer 1

如果在预分配的字节数组上创建MemoryStream,则无法扩展(即,比您启动时指定的大小更长).相反,为什么不使用:

using (var ms = new MemoryStream())
{
   // Do your thing, for example:
   m.Attachments[0].ContentStream.CopyTo(ms);

   return ms.ToArray(); // This gives you the byte array you want.
}

Answer 2

你需要更换线

m.Attachments[0].ContentStream.Write(myBuffer, 0, read);

带有写入先前创建的行的行MemoryStream，例如

foreach (MailMessage m in messages)
{
   byte[] myBuffer = null;
   if (m.Attachments.Count > 0)
   {
      //myBuffer = new byte[25 * 1024];  old way 
      myBuffer = new byte[m.Attachments[0].ContentStream.Length];
      int read;
      MemoryStream ms = new MemoryStream();
      while ((read = m.Attachments[0].ContentStream.Read(myBuffer, 0, myBuffer.Length)) > 0)
      {
          ms.Write(myBuffer, 0, read);
      }