C# 实现FTP客户端的小例子

本文是利用C# 实现FTP客户端的小例子，主要实现上传，下载，删除等功能，以供学习分享使用。

思路：

• 通过读取FTP站点的目录信息，列出对应的文件及文件夹。

• 双击目录，则显示子目录，如果是文件，则点击右键，进行下载和删除操作。

• 通过读取本地电脑的目录，以树状结构展示，选择本地文件，右键进行上传操作。
  

涉及知识点：

• FtpWebRequest【实现文件传输协议 (FTP) 客户端】 / FtpWebResponse【封装文件传输协议 (FTP) 服务器对请求的响应】Ftp的操作主要集中在两个类中。

• FlowLayoutPanel  【流布局面板】表示一个沿水平或垂直方向动态排放其内容的面板。

• ContextMenuStrip 【快捷菜单】 主要用于右键菜单。

• 资源文件：Resources 用于存放图片及其他资源。
  

效果图如下

左边：双击文件夹进入子目录，点击工具栏按钮‘上级目录'返回。文件点击右键进行操作。

右边：文件夹则点击前面+号展开。文件则点击右键进行上传。

核心代码如下

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace FtpClient
{
public class FtpHelper
{
 #region 属性与构造函数

/// <summary>
 /// IP地址
 /// </summary>
 public string IpAddr { get; set; }

/// <summary>
 /// 相对路径
 /// </summary>
 public string RelatePath { get; set; }

/// <summary>
 /// 端口号
 /// </summary>
 public string Port { get; set; }

/// <summary>
 /// 用户名
 /// </summary>
 public string UserName { get; set; }

/// <summary>
 /// 密码
 /// </summary>
 public string Password { get; set; }

public FtpHelper() {

}

public FtpHelper(string ipAddr, string port, string userName, string password) {
  this.IpAddr = ipAddr;
  this.Port = port;
  this.UserName = userName;
  this.Password = password;
 }

#endregion

#region 方法

/// <summary>
 /// 下载文件
 /// </summary>
 /// <param name="filePath"></param>
 /// <param name="isOk"></param>
 public void DownLoad(string filePath, out bool isOk) {
  string method = WebRequestMethods.Ftp.DownloadFile;
  var statusCode = FtpStatusCode.DataAlreadyOpen;
  FtpWebResponse response = callFtp(method);
  ReadByBytes(filePath, response, statusCode, out isOk);
 }

public void UpLoad(string file,out bool isOk)
 {
  isOk = false;
  FileInfo fi = new FileInfo(file);
  FileStream fs = fi.OpenRead();
  long length = fs.Length;
  string uri = string.Format("ftp://{0}:{1}{2}", this.IpAddr, this.Port, this.RelatePath);
  FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
  request.Credentials = new NetworkCredential(UserName, Password);
  request.Method = WebRequestMethods.Ftp.UploadFile;
  request.UseBinary = true;
  request.ContentLength = length;
  request.Timeout = 10 * 1000;
  try
  {
   Stream stream = request.GetRequestStream();

int BufferLength = 2048; //2K
   byte[] b = new byte[BufferLength];
   int i;
   while ((i = fs.Read(b, 0, BufferLength)) > 0)
   {
    stream.Write(b, 0, i);
   }
   stream.Close();
   stream.Dispose();
   isOk = true;
  }
  catch (Exception ex)
  {
   Console.WriteLine(ex.ToString());
  }
  finally {
   if (request != null)
   {
    request.Abort();
    request = null;
   }
  }
 }

/// <summary>
 /// 删除文件
 /// </summary>
 /// <param name="isOk"></param>
 /// <returns></returns>
 public string[] DeleteFile(out bool isOk) {
  string method = WebRequestMethods.Ftp.DeleteFile;
  var statusCode = FtpStatusCode.FileActionOK;
  FtpWebResponse response = callFtp(method);
  return ReadByLine(response, statusCode, out isOk);
 }

/// <summary>
 /// 展示目录
 /// </summary>
 public string[] ListDirectory(out bool isOk)
 {
  string method = WebRequestMethods.Ftp.ListDirectoryDetails;
  var statusCode = FtpStatusCode.DataAlreadyOpen;
  FtpWebResponse response= callFtp(method);
  return ReadByLine(response, statusCode, out isOk);
 }

/// <summary>
 /// 设置上级目录
 /// </summary>
 public void SetPrePath()
 {
  string relatePath = this.RelatePath;
  if (string.IsNullOrEmpty(relatePath) || relatePath.LastIndexOf("/") == 0 )
  {
   relatePath = "";
  }
  else {
   relatePath = relatePath.Substring(0, relatePath.LastIndexOf("/"));
  }
  this.RelatePath = relatePath;
 }

#endregion

#region 私有方法

/// <summary>
 /// 调用Ftp,将命令发往Ftp并返回信息
 /// </summary>
 /// <param name="method">要发往Ftp的命令</param>
 /// <returns></returns>
 private FtpWebResponse callFtp(string method)
 {
  string uri = string.Format("ftp://{0}:{1}{2}", this.IpAddr, this.Port, this.RelatePath);
  FtpWebRequest request; request = (FtpWebRequest)FtpWebRequest.Create(uri);
  request.UseBinary = true;
  request.UsePassive = true;
  request.Credentials = new NetworkCredential(UserName, Password);
  request.KeepAlive = false;
  request.Method = method;
  FtpWebResponse response = (FtpWebResponse)request.GetResponse();
  return response;
 }

/// <summary>
 /// 按行读取
 /// </summary>
 /// <param name="response"></param>
 /// <param name="statusCode"></param>
 /// <param name="isOk"></param>
 /// <returns></returns>
 private string[] ReadByLine(FtpWebResponse response, FtpStatusCode statusCode,out bool isOk) {
  List<string> lstAccpet = new List<string>();
  int i = 0;
  while (true)
  {
   if (response.StatusCode == statusCode)
   {
    using (StreamReader sr = new StreamReader(response.GetResponseStream()))
    {
     string line = sr.ReadLine();
     while (!string.IsNullOrEmpty(line))
     {
      lstAccpet.Add(line);
      line = sr.ReadLine();
     }
    }
    isOk = true;
    break;
   }
   i++;
   if (i > 10)
   {
    isOk = false;
    break;
   }
   Thread.Sleep(200);
  }
  response.Close();
  return lstAccpet.ToArray();
 }

private void ReadByBytes(string filePath,FtpWebResponse response, FtpStatusCode statusCode, out bool isOk)
 {
  isOk = false;
  int i = 0;
  while (true)

{
   if (response.StatusCode == statusCode)
   {
    long length = response.ContentLength;
    int bufferSize = 2048;
    int readCount;
    byte[] buffer = new byte[bufferSize];
    using (FileStream outputStream = new FileStream(filePath, FileMode.Create))
    {

using (Stream ftpStream = response.GetResponseStream())
     {
      readCount = ftpStream.Read(buffer, 0, bufferSize);
      while (readCount > 0)
      {
       outputStream.Write(buffer, 0, readCount);
       readCount = ftpStream.Read(buffer, 0, bufferSize);
      }
     }
    }
    break;
   }
   i++;
   if (i > 10)
   {
    isOk = false;
    break;
   }
   Thread.Sleep(200);
  }
  response.Close();
 }
 #endregion
}

/// <summary>
/// Ftp内容类型枚举
/// </summary>
public enum FtpContentType
{
 undefined = 0,
 file = 1,
 folder = 2
}
}

FTP服务端和客户端示意图

来源：https://www.cnblogs.com/hsiang/p/7247801.html