实现断点续传的FTP下载类（支持多线程多任务下载）

shenzhang

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using System.IO;
using System.Net;
namespace RSGIS.FTPClient
{
public class MultiFtpService
{
#region variable
private string _Server;//服务器地址
private string _UserName;//用户名
private string _Password;//密码
private string _FileUrl;//文件地址
private string _SavePath;//保存路经        
Thread _Thread;
private int _TaskIndex;
private int _ThreadIndex;
private int FileSpeed;        // 实时下载速度
private FtpWebRequest ftpRequest = null;
private FtpWebResponse ftpResponse = null;
private Stream ftpStream = null;
private int bufferSize = 2048;
private int highestPercentageReached = 0;
public delegate void DelegateDisplayProgress(int taskindex, int progress);
public DelegateDisplayProgress WorkMethod;
public delegate void DelegateDisplayFileSpeed(int taskindex, string speed);
public DelegateDisplayFileSpeed FileSpeedMethod;
#endregion
#region Constructor
public MultiFtpService(string server, string username, string password, int taskIndex, int threadIndex, string fileUrl, string savePath)
{
_Server = server;
_UserName = username;
_Password = password;
_FileUrl = fileUrl;
_SavePath = savePath;
_TaskIndex = taskIndex;
_ThreadIndex = threadIndex;
}
#endregion
#region Functions
//开始
public void Start()
{
long fileSize = GetLength();
_Thread = new Thread(() => { TheadDownload(_FileUrl, _SavePath, _TaskIndex, _ThreadIndex, fileSize); });
_Thread.Start();
}
///
/// 暂停线程
///
public void Stop()
{
_Thread.Suspend();
}
// 恢复线程
public void continues()
{
_Thread.Resume();
}
//获取文件长度
private long GetLength()
{
Ftp ftpclient = new Ftp(_Server, _UserName, _Password);
long fileSize = ftpclient.getFileSize(_FileUrl);
ftpclient = null;
return fileSize;
}
///
/// 下载
///
///
///
///
///
///
private void TheadDownload(string remoteFile, string localFile, int taskindex, int threadindex, long fileSize)
{
try
{
//续传
if (File.Exists(localFile))
{
FileInfo file = new FileInfo(localFile);
int locSize = Convert.ToInt32(file.Length);
if (locSize.ToString() != fileSize.ToString())
{
Uri FTPUri = new Uri(_Server + "/" + remoteFile);
RestartDownloadFromServer(taskindex, localFile, FTPUri, file.Length, fileSize);
}
}
else
{
// Create Request
ftpRequest = (FtpWebRequest)FtpWebRequest.Create(_Server + "/" + remoteFile);
ftpRequest.Credentials = new NetworkCredential(_UserName, _Password);
ftpRequest.UseBinary = true;
ftpRequest.UsePassive = true;
ftpRequest.KeepAlive = true;
ftpRequest.Proxy = GlobalProxySelection.GetEmptyWebProxy();
// Request Type
ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile;
// Get Response
ftpResponse = (FtpWebResponse)ftpRequest.GetResponse();
// Get server response stream
ftpStream = ftpResponse.GetResponseStream();
FileStream localFileStream = new FileStream(localFile, FileMode.Create);
// Buffer for downloaded data
byte[] byteBuffer = new byte[bufferSize];
int bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
// Download File
int fileSizes = Convert.ToInt32(fileSize);
try
{
while (bytesRead > 0)
{
localFileStream.Write(byteBuffer, 0, bytesRead);
bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
int Complete = Convert.ToInt32(fileSizes) - bytesRead;
double Fcompletes = Convert.ToDouble(Complete) / Convert.ToDouble(fileSize);
double x = 1;
double Fcomplete = x - Fcompletes;
fileSizes = Complete;
if (Fcomplete * 100 > highestPercentageReached)
{
WorkMethod(taskindex, Convert.ToInt32(Fcomplete * 100));
string speed = SizeConversion(Convert.ToInt64(bytesRead / 0.01));
FileSpeedMethod(taskindex, speed);
}
}
FileInfo file = new FileInfo(localFile);
int locSize = Convert.ToInt32(file.Length);
if (locSize.ToString() != fileSizes.ToString())
{
Uri FTPUri = new Uri(_Server + "/" + remoteFile);
RestartDownloadFromServer(taskindex, localFile, FTPUri, file.Length, fileSize);
}
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
localFileStream.Close();
ftpStream.Close();
ftpResponse.Close();
ftpRequest = null;
WorkComplete();
}
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
//catch { }
}
//断点续传
private bool RestartDownloadFromServer(int taskindex, string fileName, Uri serverUri, long offset, long fileSize)
{
if (serverUri.Scheme != Uri.UriSchemeFtp)
{
return false;
}
// 获取ftp
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(serverUri);
request.Credentials = new NetworkCredential(_UserName, _Password);
request.UseBinary = true;
request.UsePassive = true;
request.KeepAlive = true;
request.Proxy = GlobalProxySelection.GetEmptyWebProxy();
// Request Type
request.Method = WebRequestMethods.Ftp.DownloadFile;
request.ContentOffset = offset;
FtpWebResponse response = null;
try
{
response = (FtpWebResponse)request.GetResponse();
}
catch (WebException e)
{
Console.WriteLine(e.Status);
Console.WriteLine(e.Message);
return false;
}
// 获取流
ftpStream = response.GetResponseStream();
//StreamReader reader = new StreamReader(newFile);
//string newFileData = reader.ReadToEnd();
FileStream localFileStream = new FileStream(fileName, FileMode.Append);
// Buffer for downloaded data
byte[] byteBuffer = new byte[bufferSize];
int bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
// Download File
int fileSizes = Convert.ToInt32(fileSize);
try
{
while (bytesRead > 0)
{
localFileStream.Write(byteBuffer, 0, bytesRead);
bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
int Complete = Convert.ToInt32(fileSizes) - bytesRead;
double Fcompletes = Convert.ToDouble(Complete) / Convert.ToDouble(fileSize);
double x = 1;
double Fcomplete = x - Fcompletes;
fileSizes = Complete;
if (Fcomplete * 100 > highestPercentageReached)
{
Fcomplete = Fcomplete + offset / fileSize;
WorkMethod(taskindex, Convert.ToInt32(Fcomplete * 100));
string speed = SizeConversion(Convert.ToInt64(bytesRead / 0.01));
FileSpeedMethod(taskindex, speed);
}
}
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
//关闭流
localFileStream.Close();
ftpStream.Close();
response.Close();
request = null;
WorkComplete();
return true;
}
//完成
public void WorkComplete()
{
MessageBox.Show("文件下载成功", "Success", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
///
/// 文件大小换算
///
/// 文件长度
///
private string SizeConversion(long bytes)
{
int unit = 1024;
if (bytes < unit) return bytes + " B";
int exp = (int)(Math.Log(bytes) / Math.Log(unit));
return String.Format("{0:F1} {1}B", bytes / Math.Pow(unit, exp), "KMGTPE"[exp - 1]);
}
#endregion
}
}