C#实现FTP客户端的案例

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
  }
}

源码链接如下：案例

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