在 C# 中将文件从 FTP 读取到内存
本文关键字：FTP 读取 内存 文件 | 更新日期: 2023-09-27 17:57:15
我想从FTP服务器读取文件而不将其下载到本地文件。我写了一个函数，但它不起作用：
private string GetServerVersion()
{
WebClient request = new WebClient();
string url = FtpPath + FileName;
string version = "";
request.Credentials = new NetworkCredential(ftp_user, ftp_pas);
try
{
byte[] newFileData = request.DownloadData(new Uri(FtpPath)+FileName);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
}
catch (WebException e)
{
}
return version;
}
下面是一个简单的工作示例，使用您的代码从Microsoft公共 FTP 服务器获取文件：
WebClient request = new WebClient();
string url = "ftp://ftp.microsoft.com/developr/fortran/" +"README.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
try
{
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
Console.WriteLine(fileString);
}
catch (WebException e)
{
// Do something such as log error, but this is based on OP's original code
// so for now we do nothing.
}
我认为您在代码中的这一行缺少斜杠：
string url = FtpPath + FileName;
也许在FtpPath和FileName之间？
小二进制文件
如果文件很小，最简单的方法是使用 WebClient.DownloadData：
WebClient client = new WebClient();
string url = "ftp://ftp.example.com/remote/path/file.zip";
client.Credentials = new NetworkCredential("username", "password");
byte[] contents = client.DownloadData(url);
小文本文件
如果小文件是文本文件，请使用WebClient.DownloadString：
string contents = client.DownloadString(url);
它假定文件内容采用 UTF-8 编码（纯 ASCII 文件也可以）。如果需要使用其他编码，请使用WebClient.Encoding属性。
大型二进制文件
如果文件很大，因此您需要分块处理它，而不是将其加载到整个内存中，请使用 FtpWebRequest ：
FtpWebRequest request =
(FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;
using (Stream stream = request.GetResponse().GetResponseStream())
{
byte[] buffer = new byte[10240];
int read;
while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
{
// process the chunk in "buffer"
}
}
您还可以通过使用 WebClient.OpenRead 来简化代码。
大型文本文件
如果大文件是文本文件，并且您希望按行而不是固定大小的块处理它，请使用 StreamReader ：
FtpWebRequest request =
(FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.txt");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;
using (Stream stream = request.GetResponse().GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
{
while (!reader.EndOfStream)
{
string line = reader.ReadLine();
// process the line
Console.WriteLine(line);
}
}
同样，这假定使用 UTF-8 编码。如果要使用其他编码，请使用StreamReader构造函数的重载，该构造函数也需要Encoding。
与前面一样，您可以使用 WebClient.OpenRead 来简化代码。
流接口
但是，在许多情况下，您需要在某个使用 Stream 接口的 API 中使用下载的数据。在这种情况下，不要使用上述任何解决方案，而是直接使用 API 中的request.GetResponse().GetResponseStream()或WebClient.OpenRead返回的流。
有关示例，请参阅在 C# 中将文件从 FTP 直接传输到 Azure Blob 存储。
您上面的代码与我 2 天前发现并使用的另一个 Stackoverlow 示例非常相似。 如果您正确设置了 URI、用户和密码，它将下载文件并将内容设置为 FileString。 我不确定您想在不下载文件的情况下阅读文件是什么意思。 这不是一个真正的选择。
如果你想查看文件属性（我看到你提到了"版本"），你可以使用下面的代码从FTP服务器获取所有文件名，数据和大小，而无需下载文件。
调用 GetFileInfo 并传入文件名（确保按照代码设置完整的 FTP 路径、用户和密码）。 这将返回一个具有名称、日期和大小的 FTPFileInfo 对象。
public static FTPFileInfo GetFileInfo(string fileName)
{
var dirInfo = WordstockExport.GetFTPDirectoryDetails();
var list = FTPFileInfo.Load(dirInfo);
try
{
FTPFileInfo ftpFile = list.SingleOrDefault(f => f.FileName == fileName);
return ftpFile;
}
catch { }
return null;
}
class FTPFileInfo
{
private DateTime _FileDate;
private long _FileSize;
private string _FileName;
public DateTime FileDate
{
get { return _FileDate; }
set { _FileDate = value; }
}
public long FileSize
{
get { return _FileSize; }
set { _FileSize = value; }
}
public string FileName
{
get { return _FileName; }
set { _FileName = value; }
}
public FTPFileInfo() { }
public static FTPFileInfo LoadFromLine(string line)
{
FTPFileInfo file = new FTPFileInfo();
string[] ftpFileInfo = line.Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
file._FileDate = DateTime.Parse(ftpFileInfo[0] + " " + ftpFileInfo[1]);
file._FileSize = long.Parse(ftpFileInfo[2]);
file._FileName = ftpFileInfo[3];
return file;
}
public static List<FTPFileInfo> Load(string listDirectoryDetails)
{
List<FTPFileInfo> files = new List<FTPFileInfo>();
string[] lines = listDirectoryDetails.Split("'r'n".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
foreach(var line in lines)
files.Add(LoadFromLine(line));
return files;
}
}
private static string GetFTPDirectoryDetails()
{
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(App.Export_FTPPath);
request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
request.Credentials = new NetworkCredential(App.FTP_User, App.FTP_Password);
FtpWebResponse response = (FtpWebResponse)request.GetResponse();
Stream responseStream = response.GetResponseStream();
StreamReader reader = new StreamReader(responseStream);
string fileLines = reader.ReadToEnd();
reader.Close();
response.Close();
return fileLines;
}
如果没有有关错误/异常的详细信息，就不可能知道问题是什么。
猜测，您似乎没有在初始声明后为version分配新值
string version = "";
尝试将代码更改为
version = System.Text.Encoding.UTF8.GetString(newFileData);
C Sharp GUI 应用程序。 最小的ftp传输，不优雅，但工作正常。GUI，而不是控制台。
来自诺阿的天气。找到你的地区（寻找你的元）！METAR天气报告主要由飞行员用于完成飞行前
的一部分使用 vs 2012高级 RC 构建（2012 年 7 月）
（点击标签，而不是按钮）
using System;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
using System.Collections.Generic;
namespace getweather
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button2_Click(object sender, EventArgs e)
{
Application.Exit();
}
private void CYYY_Click(object sender, EventArgs e)
{
WebClient request = new WebClient();
string url = "ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYYY.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
richTextBox1.Text = fileString;
}
private void CYSC_Click(object sender, EventArgs e)
{
WebClient request = new WebClient();
string url = "ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYSC.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
richTextBox1.Text = fileString;
}
private void CYQB_Click(object sender, EventArgs e)
{
WebClient request = new WebClient();
string url = "ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYQB.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
richTextBox1.Text = fileString;
}
private void CYUY_Click(object sender, EventArgs e)
{
WebClient request = new WebClient();
string url = "ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYUY.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
richTextBox1.Text = fileString;
}
private void CYHU_Click(object sender, EventArgs e)
{
WebClient request = new WebClient();
string url = "ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYHU.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
richTextBox1.Text = fileString;
}
}
}
WebClient request = new WebClient();
string url = "ftp://ftp.microsoft.com/developr/fortran/" +"README.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
request.Proxy = null;
try
{
byte[] newFileData = request.DownloadData(url);
string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
Console.WriteLine(fileString);
}
catch (WebException e)
{
// Do something such as log error, but this is based on OP's original code
// so for now we do nothing.
}
我知道
这是一个老问题，但我想我建议下一个阅读本文的人使用 path.combe。 帮助清理此类问题。
string url = Path.Combine("ftp://ftp.microsoft.com/developr/fortran", "README.TXT");
我们可以使用以下方法从 ftp 获取文件属性，而无需下载文件。这对我来说很好用。
public DataTable getFileListFTP(string serverIP,string userID,string Password)
{
DataTable dt = new DataTable();
string[] fileListArr;
string fileName = string.Empty;
long fileSize = 0;
// DateTime creationDate;
string creationDate;
FtpWebRequest Request = (FtpWebRequest)WebRequest.Create(serverIP);
Request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
Request.Credentials = new NetworkCredential(userID,Password);
FtpWebResponse Response = (FtpWebResponse)Request.GetResponse();
Stream ResponseStream = Response.GetResponseStream();
StreamReader Reader = new StreamReader(ResponseStream);
dt.Columns.Add("FileName", typeof(String));
dt.Columns.Add("FileSize", typeof(String));
dt.Columns.Add("CreationDate", typeof(DateTime));
//CultureInfo c = new CultureInfo("ES-ES");
while (!Reader.EndOfStream)//Read file name
{
fileListArr = Convert.ToString(Reader.ReadLine()).Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
fileSize = long.Parse(fileListArr[4]);
creationDate = fileListArr[6] + " " + fileListArr[5] + " " + fileListArr[7];
//creationDate =Convert.ToDateTime(fileListArr[6] + " " + fileListArr[5] + " " + fileListArr[7], c).ToString("dd/MMM/yyyy", DateTimeFormatInfo.InvariantInfo);
fileName = Convert.ToString(fileListArr[8]);
DataRow drow = dt.NewRow();
drow["FileName"] = fileName;
drow["FileSize"] = fileName;
drow["CreationDate"] = creationDate;
dt.Rows.Add(drow);
}
Response.Close();
ResponseStream.Close();
Reader.Close();
return dt;
}
看看我的FTP类，它可能正是你所需要的。
Public Class FTP
'-------------------------[BroCode]--------------------------
'----------------------------FTP-----------------------------
Private _credentials As System.Net.NetworkCredential
Sub New(ByVal _FTPUser As String, ByVal _FTPPass As String)
setCredentials(_FTPUser, _FTPPass)
End Sub
Public Sub UploadFile(ByVal _FileName As String, ByVal _UploadPath As String)
Dim _FileInfo As New System.IO.FileInfo(_FileName)
Dim _FtpWebRequest As System.Net.FtpWebRequest = CType(System.Net.FtpWebRequest.Create(New Uri(_UploadPath)), System.Net.FtpWebRequest)
_FtpWebRequest.Credentials = _credentials
_FtpWebRequest.KeepAlive = False
_FtpWebRequest.Timeout = 20000
_FtpWebRequest.Method = System.Net.WebRequestMethods.Ftp.UploadFile
_FtpWebRequest.UseBinary = True
_FtpWebRequest.ContentLength = _FileInfo.Length
Dim buffLength As Integer = 2048
Dim buff(buffLength - 1) As Byte
Dim _FileStream As System.IO.FileStream = _FileInfo.OpenRead()
Try
Dim _Stream As System.IO.Stream = _FtpWebRequest.GetRequestStream()
Dim contentLen As Integer = _FileStream.Read(buff, 0, buffLength)
Do While contentLen <> 0
_Stream.Write(buff, 0, contentLen)
contentLen = _FileStream.Read(buff, 0, buffLength)
Loop
_Stream.Close()
_Stream.Dispose()
_FileStream.Close()
_FileStream.Dispose()
Catch ex As Exception
MessageBox.Show(ex.Message, "Upload Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub
Public Sub DownloadFile(ByVal _FileName As String, ByVal _ftpDownloadPath As String)
Try
Dim _request As System.Net.FtpWebRequest = System.Net.WebRequest.Create(_ftpDownloadPath)
_request.KeepAlive = False
_request.Method = System.Net.WebRequestMethods.Ftp.DownloadFile
_request.Credentials = _credentials
Dim _response As System.Net.FtpWebResponse = _request.GetResponse()
Dim responseStream As System.IO.Stream = _response.GetResponseStream()
Dim fs As New System.IO.FileStream(_FileName, System.IO.FileMode.Create)
responseStream.CopyTo(fs)
responseStream.Close()
_response.Close()
Catch ex As Exception
MessageBox.Show(ex.Message, "Download Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub
Public Function GetDirectory(ByVal _ftpPath As String) As List(Of String)
Dim ret As New List(Of String)
Try
Dim _request As System.Net.FtpWebRequest = System.Net.WebRequest.Create(_ftpPath)
_request.KeepAlive = False
_request.Method = System.Net.WebRequestMethods.Ftp.ListDirectoryDetails
_request.Credentials = _credentials
Dim _response As System.Net.FtpWebResponse = _request.GetResponse()
Dim responseStream As System.IO.Stream = _response.GetResponseStream()
Dim _reader As System.IO.StreamReader = New System.IO.StreamReader(responseStream)
Dim FileData As String = _reader.ReadToEnd
Dim Lines() As String = FileData.Split(New String() {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
For Each l As String In Lines
ret.Add(l)
Next
_reader.Close()
_response.Close()
Catch ex As Exception
MessageBox.Show(ex.Message, "Directory Fetch Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
Return ret
End Function
Private Sub setCredentials(ByVal _FTPUser As String, ByVal _FTPPass As String)
_credentials = New System.Net.NetworkCredential(_FTPUser, _FTPPass)
End Sub
End Class
要初始化：
Dim ftp As New FORM.FTP("username", "password")
ftp.UploadFile("c:'file.jpeg", "ftp://domain/file.jpeg")
ftp.DownloadFile("c:'file.jpeg", "ftp://ftp://domain/file.jpeg")
Dim directory As List(Of String) = ftp.GetDirectory("ftp://ftp.domain.net/")
ListBox1.Items.Clear()
For Each item As String In directory
ListBox1.Items.Add(item)
Next
https://stackoverflow.com/a/28669746/2701974