C# - 文件上传到服务器后损坏

我使用以下源代码上传文件excel和pdf，但是将文件移动到服务器后，文件已损坏。我认为问题出在编码过程上Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());，但我不知道如何解决。

public static void sampleUpload()
    {
        // Get the object used to communicate with the server.
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://100.165.80.15:21/output/Group Dealer, Main Dealer, Zone, Branch, and Destination Report_20120927105003.pdf");
        request.Method = WebRequestMethods.Ftp.UploadFile;

        // This example assumes the FTP site uses anonymous logon.
        request.Credentials = new NetworkCredential("toc", "fid123!!");

        // Copy the contents of the file to the request stream.
        StreamReader sourceStream = new StreamReader("D:\\Group Dealer, Main Dealer, Zone, Branch, and Destination Report_20120927105003.pdf");
        byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
        sourceStream.Close();
        request.ContentLength = fileContents.Length;

        Stream requestStream = request.GetRequestStream();
        requestStream.Write(fileContents, 0, fileContents.Length);
        requestStream.Close();

        FtpWebResponse response = (FtpWebResponse)request.GetResponse();

        Console.WriteLine("Upload File Complete, status {0}", response.StatusDescription);

        response.Close();
    }

不要将二进制文件作为文本读取。使用流.复制到方法（或等效代码，如果您不能使用 .Net 4.0）

 using(StreamReader sourceStream = ...){
   using(Stream requestStream = request.GetRequestStream())
   {
     sourceStream.CopyTo(requestStream);
   }
 }