如何使用c＃从FTP下载大于1MB的文件

Question

I have created a C# application for downloading file from FTP. I could not download files having size greater than 1 MB. I got an error "Data is corrupted" while downloading the file. Here is my code for download.

int count = 0;
do
{
    byte[] buffer = new byte[1024];
    conn.ReadTimeout = 15000000;
    count = istream.Read(buffer, 0, buffer.Length);
    memoryStream.Write(buffer, 0, count);
} while (istream.CanRead && count > 0);

byteArray = memoryStream.ToArray();
var workBook = new XLWorkbook(memoryStream);
var workSheet = workBook.Worksheets.First();

Answer 1

The problem with your code that when you read data from istream and in there is no more data it will return count 0, and you need to exit your loop, instead of reading data to the memoryStream.

Try this:

while(true)
{
    byte[] buffer = new byte[1024];
    conn.ReadTimeout = 15000000;
    count = istream.Read(buffer, 0, buffer.Length);

    if (count == 0)
        break;

    memoryStream.Write(buffer, 0, count);
}

istream.Close();

byteArray = memoryStream.ToArray();
var workBook = new XLWorkbook(memoryStream);
var workSheet = workBook.Worksheets.First()

Also close your istream after the loop, otherwise downloaded file might get truncated and that might be the reason why you are getting "Data is corrupted" error.

Answer 2

Its an issue with firewall blocking from my system on uploading data to FTP server. The uploaded data is corrupted on the FTP server and I am trying to download the same corrupted data using my code.