C#从FTP下载文件无法返回文件长度
我要从FTP服务器下载指定文件，比如A.zip 大小100kb，等下载成功，这个文件名，大小等信息会被存入一个数据库，等下次下载的时候会去比较，如果两个文件大小一致，就不下了，现在出了一个问题，返回的contentLength始终为-1，但是东西还是有的，可以下载下来，FTP是我自己临时搭建的，系统为win7，网络为政务外网，但是我家里自己测试的时候，用的清华大学FTP，可以返回文件大小，不知道怎么回事，是FTP设置的问题吗?查了MSDN说如果服务器没有返回长度则是-1，怎么搞？
private void FileDownload()
{
FtpWebResponse m_FtpWebResponse = null;
try
{
bLastDownloadFinish = false;
for (int i = 0; i < downloadList.Count; i++)
{
bFlag = false;
WriteLog("准备下载[" + downloadList[i] + "]");
WriteLog("开始连接FTP...");
m_FtpWebRequest = (FtpWebRequest)FtpWebRequest.Create(sIp + sSourceDir + downloadList[i]);
m_FtpWebRequest.Credentials = new NetworkCredential(sUser, sPwd);
m_FtpWebRequest.Timeout = 30000;
m_FtpWebRequest.UseBinary = true;
m_FtpWebRequest.Method = WebRequestMethods.Ftp.DownloadFile;
try
{
m_FtpWebResponse = (FtpWebResponse)m_FtpWebRequest.GetResponse();
}
catch (Exception ex)
{
WriteLog("FTP文件大小查询失败，原因:" + ex.Message);
continue;
}
WriteLog("FTP文件大小查询成功");
Stream ftpResponseStream = m_FtpWebResponse.GetResponseStream();
//sr = new StreamReader(ftpResponseStream);
long contentLength = m_FtpWebResponse.ContentLength; //始终为-1
if (!Directory.Exists(sTargetDir))
{
Directory.CreateDirectory(sTargetDir);
}
SQLiteDataReader reader = m_DbSqlite.GetReader(string.Format("select * from log where FileName='{0}'", downloadList[i]));
if (reader.HasRows)
{
bFlag = true;
if (reader.Read())
{
if (reader["Length"].ToString() != contentLength.ToString())
{
WriteLog("与原始文件大小不一致，重新下载，大小[" + contentLength.ToString() + "]");
ReDownLoad(ftpResponseStream, downloadList[i]);
}
else
{
WriteLog("已下载过大小一致的此文件，放弃下载!");
}
}
}
else
{
WriteLog("无此文件，开始下载，大小[" + contentLength.ToString() + "]");
ReDownLoad(ftpResponseStream, downloadList[i]);
}
reader.Close();
ftpResponseStream.Close();
//m_FtpWebResponse.Close();
//m_FtpWebResponse.Dispose();
WriteLog("下载结束!");
WriteLog("======================================================");
}
}
catch (Exception ex)
{
WriteLog("下载线程发生错误：" + ex.Message);
}
finally
{
if (m_FtpWebResponse.StatusCode != FtpStatusCode.ConnectionClosed)
{
m_FtpWebResponse.Close();
}
bLastDownloadFinish = true;
}
}
private void ReDownLoad(Stream ftpResponseStream, string file)
{
try
{
try
{
if (File.Exists(sTargetDir + file + ".tmp"))
{
File.Delete(sTargetDir + file + ".tmp");
}
}
catch
{
}
m_BeginTime = FormatTime(DateTime.Now);
long length = 0;
using (FileStream outputStream = new FileStream(sTargetDir + file + ".tmp", FileMode.Create))
{
int bufferSize = 2048;
byte[] buffer = new byte[bufferSize];
List<int> test = new List<int>();
int c = 0;
while ((c = ftpResponseStream.ReadByte()) != -1)
{
outputStream.WriteByte(Convert.ToByte(c));
}
length = outputStream.Length;
m_EndTime = FormatTime(DateTime.Now);
outputStream.Close();
}
string sql = "";
if (bFlag)
{
sql = string.Format("update log set Length='{0}',BeginTime='{1}',EndTime='{2}' where FileName='{3}'", length.ToString(), m_BeginTime.ToString(), m_EndTime.ToString(), file);
}
else
{
sql = string.Format("insert into log(FileName,Length,BeginTime,EndTime) values('{0}','{1}','{2}','{3}')", file, length.ToString(), m_BeginTime.ToString(), m_EndTime.ToString());
}
if (m_DbSqlite.ExcuteSql(sql) != 1)
{
WriteLog("更新数据库信息失败");
}
WriteLog("下载后文件大小:[" + length.ToString() + "]");
if (File.Exists(sTargetDir + file))
{
File.Delete(sTargetDir + file);
}
File.Move(sTargetDir + file + ".tmp", sTargetDir + file);
}
catch (Exception ex)
{
WriteLog("下载出错:" + ex.Message);
}
}
补充：.NET技术 , C#
