ftp图片上传下载带进度条

            ftp:是一种协议，文件传输协议。ftp的主要作用，就是让用户连接一个远程计算机查看远程计算机有哪些文件，然后把文件从远程计算机上拷贝到本地计算机，或者把本地文件发送到远程计算机上。文件的发送与接受都是以流的方式进行的。

本篇博文主要介绍winform上ftp对图片的上传和下载以及进度条对应的显示。进度条主要是为了让用户知道图片上传了多少，还有多久上传完成，以及是否上传完成。下载图片也还是一样的效果。

首先看一下界面运行后的结果：

先贴上底层类的方法：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Windows.Forms;
using System.Configuration;
using System.Drawing;

namespace WinformFTP
{
    public class FTPTools
    {

	//创建请求对象。
        private static FtpWebRequest GetRequest(string URI, string username, string password)
        {
            FtpWebRequest result = (FtpWebRequest)FtpWebRequest.Create(URI);
            result.Credentials = new System.Net.NetworkCredential(username, password);
            result.KeepAlive = false;
            return result;
        }

        //Ftp路径
        static string FtpUrl
        {
            get
            {
                return ConfigurationManager.ConnectionStrings["FtpUrl"].ToString();
            }
        }

        //Ftp文件件
        static string BusinessCard
        {
            get
            {
                return ConfigurationManager.ConnectionStrings["FtpFolder"].ToString();
            }
        }

        //上传图片的方法。
        public void uploadPicture(string path, ProgressBar proImage, PictureBox picImage, Label lblPro, Label lblDate, Label lblState, Label lblSpeed)
        {
            if (!string.IsNullOrEmpty(path) && File.Exists(path))
            {
                FileInfo file = new FileInfo(path);
                int j = file.Name.LastIndexOf('.');
                string filename = Guid.NewGuid().ToString();
                string fullname = filename + file.Name.Substring(j, 4);//获取文件名 和 后缀名

                UploadFile(file, fullname, "", "", proImage, picImage, lblPro, lblDate, lblState, lblSpeed, path);
            }
        }
        //时间。
        private string strDate;

        /// <summary>
        /// 上传文件
        /// </summary>
        /// <param name="fileinfo">需要上传的文件</param>
        /// <param name="targetDir">目标路径</param>
        /// <param name="hostname">ftp地址</param>
        /// <param name="username">ftp用户名</param>
        /// <param name="password">ftp密码</param>
        private void UploadFile(FileInfo fileinfo, string filename, string username, string password, ProgressBar proImage, PictureBox picImage, Label lblPro, Label lblDate, Label lblState, Label lblSpeed, string path)
        {
            if (BusinessCard.Trim() == "")
            {
                return;
            }

            proImage.Value = 0;
            string URI = "FTP://" + FtpUrl + "/" + BusinessCard + "/" + filename;
            System.Net.FtpWebRequest ftp = GetRequest(URI, username, password);

            //设置FTP命令
            ftp.Method = System.Net.WebRequestMethods.Ftp.UploadFile;
            ftp.UseBinary = true;
            ftp.UsePassive = true;

            //告诉ftp文件大小
            ftp.ContentLength = fileinfo.Length;

            const int BufferSize = 2048;
            byte[] content = new byte[BufferSize];
            int dataRead = 0;

            //上传文件内容
            using (FileStream fs = fileinfo.OpenRead())
            {
                try
                {
                    using (Stream rs = ftp.GetRequestStream())
                    {
                        //已上传的字节数   
                        long offset = 0;
                        long length = fs.Length;
                        DateTime startTime = DateTime.Now;
                        proImage.Maximum = int.MaxValue;
                        do
                        {
                            offset += dataRead;
                            proImage.Value = (int)(offset * (int.MaxValue / length));
                            TimeSpan span = DateTime.Now - startTime;
                            double second = span.TotalSeconds;
                            lblPro.Text = lblDate.Text = lblState.Text = lblSpeed.Text = "";

                            strDate = second.ToString("F2") + "秒";
                            lblDate.Text = "已用时：" + second.ToString("F2") + "秒";
                            if (second > 0.001)
                            {
                                lblSpeed.Text = "平均速度：" + (offset / 1024 / second).ToString("0.00") + "KB/秒";
                            }
                            else
                            {
                                lblSpeed.Text = "正在连接…";
                            }

                            lblState.Text = "已上传：" + (offset * 100.0 / length).ToString("F2") + "%   ";
                            lblPro.Text = "图片大小：" + (offset / 1048576.0).ToString("F2") + "M/" + (length / 1048576.0).ToString("F2") + "M";

                            dataRead = fs.Read(content, 0, BufferSize);
                            rs.Write(content, 0, dataRead);
                        } while (dataRead > 0);

                        lblDate.Text = "已用时：" + strDate;
                        picImage.Image = Image.FromFile(path);

                        rs.Close();
                    }
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    fs.Close();
                }
            }
            ftp = null;
        }

	//下载图片处理。
        public void DownloadFile(string localDir, string FtpDir, string FtpFile, string hostname, string username, string password, ProgressBar proImage, Label lblPro, PictureBox picImage)
        {
            float percent = 0;

            string URI = "FTP://" + hostname + "/" + FtpDir + "/" + FtpFile;
            string tmpname = Guid.NewGuid().ToString();
            string localfile = localDir + @"\" + FtpFile;

            FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(URI);
            request.Credentials = new System.Net.NetworkCredential(username, password);
            request.Method = WebRequestMethods.Ftp.GetFileSize;
            long totalBytes = 0;
            using (FtpWebResponse rep = (FtpWebResponse)request.GetResponse())
            {
                totalBytes = rep.ContentLength;
            }

            System.Net.FtpWebRequest ftp = GetRequest(URI, username, password);
            ftp.Method = System.Net.WebRequestMethods.Ftp.DownloadFile;
            ftp.UseBinary = true;

            using (FtpWebResponse response = (FtpWebResponse)ftp.GetResponse())
            {
                using (Stream responseStream = response.GetResponseStream())
                {
                    if (!Directory.Exists(localDir))
                    {
                        Directory.CreateDirectory(localDir);
                    }

                    using (FileStream fs = new FileStream(localfile, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                    {
                        try
                        {
                            if (proImage != null)
                            {
                                proImage.Maximum = (int)totalBytes;
                            }
                            long totalDownloadedByte = 0;
                            byte[] buffer = new byte[2048];
                            int read = 0;

                            lblPro.Text = "下载图片正在加载......";
                            do
                            {
                                totalDownloadedByte += read;
                                if (proImage != null)
                                {
                                    proImage.Value = (int)totalDownloadedByte;
                                }
                                read = responseStream.Read(buffer, 0, buffer.Length);
                                fs.Write(buffer, 0, read);
                                percent = (float)totalDownloadedByte / (float)totalBytes * 100;

                                lblPro.Text = "";
                                lblPro.Text = "当前图片下载进度" + percent.ToString() + "%";
                            } while (read > 0);

                            if ((int)percent == 100)
                            {
                                picImage.Image = Image.FromStream(fs);
                            }

                            fs.Flush();
                            fs.Close();
                        }
                        catch (Exception)
                        {
                            fs.Close();
                            File.Delete(localfile);
                            throw;
                        }
                    }
                    File.Delete(localfile);
                    responseStream.Close();
                }

                response.Close();
            }

            ftp = null;
        }
    }
}

其中要注意，下载方法DownloadFile中的代码。下载图片到的处理是，从远程服务器上获得流，再把流绑定到PictureBox控件上（ picImage.Image =Image.FromStream(fs);）。这就说明要远程服务器要返回流。因为同时要让进度条ProgressBar 控件反应下载的进度。所以也要获得下载图片的大小（rep.ContentLength），也许有人说这有什么难的，直接把他们都返回就是的了，关键是一次不能返回。原因如下：

ContentLength - 设置这个属性对于ftp服务器是有用的，但是客户端不使用它，因为FtpWebRequest忽略这个属性，所以在这种情况下，该属性是无效的。但是如果 我们设置了这个属性，ftp服务器将会提前预知文件的大小（在upload时会有这种情况）

所以我上面就只能请求两次了，这是最纠结我的地方，我试了很多方法，都不行，最后也只能用这一种方法了。上传的应该没有什么好说的，看代码就可以懂的。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Configuration;
using System.IO;
using System.Net;
using System.Threading;

namespace WinformFTP
{
    public partial class FrmFtp : Form
    {
        //图片名称。
        public string path;

        //图片大小。
        public long ImageLength;

        public FrmFtp()
        {
            InitializeComponent();
        }

        //下载图片方法
        private string loadPicture(string path)
        {
            FileInfo file = new FileInfo(path);
            int j = file.Name.LastIndexOf('.');
            string filename = Guid.NewGuid().ToString();
            string fullname = filename + file.Name.Substring(j, 4);//获取文件名 和 后缀名
            string uri = String.Format("FTP://{0}/{1}/{2}",
                ConfigurationManager.ConnectionStrings["FtpUrl"].ToString(),
                ConfigurationManager.ConnectionStrings["FtpFolder"].ToString(),
                fullname);
            return uri;
        }

        //上传图片。
        private void btnFtp_Click(object sender, EventArgs e)
        {
            this.picImage.Image = null;

            Thread thread = new Thread(new ThreadStart(GetImage));
            thread.SetApartmentState(ApartmentState.STA);
            Control.CheckForIllegalCrossThreadCalls = false;
            thread.Start();
        }

        //筛选图片。
        private void GetImage()
        {
            openFileDialog1.FileName = string.Empty;
            openFileDialog1.Filter = "图片(jpg,bmp,png,jpeg)|*.JPG;*.PNG;*.BMP;*.JPEG";
            openFileDialog1.InitialDirectory = @"c:\windows\ ";
            openFileDialog1.Multiselect = false;
            openFileDialog1.AddExtension = true;
            openFileDialog1.DereferenceLinks = true;
            openFileDialog1.CheckFileExists = true;
            openFileDialog1.CheckPathExists = true;

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if (openFileDialog1.FileName != string.Empty)
                {
                    path = openFileDialog1.FileName;
                    txtImage.Text = path;
                    lblState.Text = "图片正在加载.......";

                    FTPTools ftpTools = new FTPTools();
                    ftpTools.uploadPicture(path, proImage, picImage, lblPro, lblDate, lblState, lblSpeed);
                }
            }
        }

        //根据图片名称下载图片。
        private void btnDownload_Click(object sender, EventArgs e)
        {
            new Thread(new ThreadStart(DownloadMyImage)).Start();
        }

        //下载图片。
        private void DownloadMyImage()
        {
            if (string.IsNullOrWhiteSpace(txtImage.Text))
            {
                MessageBox.Show("请填写图片的名称，以下载图片！");
                return;
            }

            if (IsExists(txtImage.Text))
            {
                this.picImage.Image = null;
                path = loadPicture(txtImage.Text);

                if (!string.IsNullOrWhiteSpace(path))
                {
                    this.picImage.Image = null;
                    this.proImage.Value = 0;

                    FTPTools ftpTools = new FTPTools();
                    ftpTools.DownloadFile(@"C:\myImages", "BusinessCard", txtImage.Text, "119.254.69.18:29", "", "", proImage, lblPro, picImage);
                }
            }
        }

        //// 获取FTP图片文件是否存在
        public static bool IsExists(string fileName)
        {
            List<string> list = FTPTools.ListDirectory(ConfigurationManager.ConnectionStrings["FtpFolder"].ToString(), ConfigurationManager.ConnectionStrings["FtpUrl"].ToString(), "", "", fileName);
            if (list == null)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
    }
}