using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Net;
namespace FtpClient
{
public class FtpFileDownloadService
{
#region 变量
private string _Server;//服务器地址
private string _UserName;//用户名
private string _Password;//密码
private int _Port;//端口
private long _FileSize;//文件大小
private string _FileUrl;//文件地址
private string _SavePath;//保存路经
private string _SaveFileName;//保存文件名
private string _SaveFileExtName;//保存文件扩展名
private int _TaskNum;//任务数量
private volatile int _DownloadSize;//当前下载大小
private Task[] _TaskList;//任务数组
private List<string> _TempFiles = new List<string>();
private FtpWebRequest ftpRequest;
#endregion
#region 属性
/// <summary>
/// 服务器地址
/// </summary>
public string Server
{
get { return _Server; }
set { _Server = value; }
}
/// <summary>
/// 用户名
/// </summary>
public string UserName
{
get { return _UserName; }
set { _UserName = value; }
}
/// <summary>
/// 密码
/// </summary>
public string Password
{
get { return _Password; }
set { _Password = value; }
}
/// <summary>
/// 端口
/// </summary>
public int Port
{
get { return _Port; }
set { _Port = value; }
}
/// <summary>
/// 文件大小
/// </summary>
public long FileSize
{
get { return _FileSize; }
set { _FileSize = value; }
}
/// <summary>
/// 文件地址
/// </summary>
public string FileUrl
{
get { return _FileUrl; }
set { _FileUrl = value; }
}
/// <summary>
/// 保存路经
/// </summary>
public string SavePath
{
get { return _SavePath; }
set { _SavePath = value; }
}
/// <summary>
/// 保存文件名
/// </summary>
public string SaveFileName
{
get { return _SaveFileName; }
set { _SaveFileName = value; }
}
/// <summary>
/// 保存文件扩展名
/// </summary>
public string SaveFileExtName
{
get { return _SaveFileExtName; }
set { _SaveFileExtName = value; }
}
/// <summary>
/// 任务数量
/// </summary>
public int TaskNum
{
get { return _TaskNum; }
set { _TaskNum = value; }
}
public int DownloadSize
{
get { return _DownloadSize; }
}
/// <summary>
/// 服务器请求地址
/// </summary>
public string RequestPath
{
get { return string.Format("ftp://{0}:{1}//{2}", _Server, _Port, _FileUrl); }
}
public string SaveFullFileName
{
get { return Path.Combine(_SavePath, _SaveFileName + _SaveFileExtName); }
}
#endregion
#region Constructor
public FtpFileDownloadService(string server, string username, string password, string fileUrl, string savePath)
: this(server, username, password, 5, fileUrl, savePath)
{
}
public FtpFileDownloadService(string server, string username, string password, int taskNum, string fileUrl, string savePath)
: this(server, username, password, 21, taskNum, fileUrl, savePath, "", "")
{
var fi = new FileInfo(fileUrl.Replace("//", "\"));
_SaveFileName = fi.Name.Substring(0, fi.Name.IndexOf('.'));
_SaveFileExtName = fi.Extension;
}
public FtpFileDownloadService(string server, string username, string password, int port, int taskNum, string fileUrl, string savePath, string saveFileName, string saveFileExtName)
{
_TaskList = new Task[taskNum];
_Server = server;
_UserName = username;
_Password = password;
_Port = port;
_TaskNum = taskNum;
_FileUrl = fileUrl;
_SavePath = savePath;
_SaveFileName = saveFileName;
_SaveFileExtName = saveFileExtName;
}
#endregion
#region Functions
public async Task Download()
{
FtpWebResponse response = null;
Stream ftpStream = null;
try
{
if (!Directory.Exists(_SavePath)) Directory.CreateDirectory(_SavePath);
_FileSize = GetFileSize();
int singelNum = (int)(_FileSize / _TaskNum);//平均分配
int remainder = (int)(_FileSize % _TaskNum);//获取剩余的
FtpWebRequest ftpRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri(RequestPath));
ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile;
ftpRequest.KeepAlive = false;
ftpRequest.UseBinary = true;
ftpRequest.Credentials = new NetworkCredential(_UserName, _Password);
response = (FtpWebResponse)ftpRequest.GetResponse();
ftpStream = response.GetResponseStream();
for (int i = 0; i < _TaskNum; i++)
{
int from = i * singelNum;
int to = i * singelNum + singelNum - 1;
if (remainder != 0 && (_TaskNum - 1) == i)//剩余的交给最后一个任务
{
to += remainder;
}
_TaskList[i] = Task.Run(() => { DownloadFile(ftpStream, from, to, "task" + i + 1); });
}
await Task.WhenAll(_TaskList);
ftpStream.Close();
response.Close();
Complete();
}
catch (Exception ex)
{
ftpStream.Close();
response.Close();
throw ex;
}
}
/// <summary>
/// 拆分分段下载
/// </summary>
private void DownloadFile(Stream stream, int from, int to, string id)
{
string tmpFileBlock = string.Format(@"{0}{1}_{2}.dat", _SavePath, _SaveFileName, id);
_TempFiles.Add(tmpFileBlock);
int readCount = 0;
int bufferSize = 4096;
byte[] buffer = new byte[bufferSize];
using (FileStream outputStream = new FileStream(tmpFileBlock, FileMode.Create))
{
while ((readCount = stream.Read(buffer, 0, bufferSize)) > 0)
{
if (from + readCount < to)
{
outputStream.Write(buffer, 0, readCount);
from = from + readCount;
}
else
{
outputStream.Write(buffer, 0, to - from);
break;
}
}
}
}
/// <summary>
/// 合并临时文件
/// </summary>
private void Complete()
{
Stream mergeFile = new FileStream(SaveFullFileName, FileMode.Create);
BinaryWriter AddWriter = new BinaryWriter(mergeFile);
foreach (string file in _TempFiles)
{
using (FileStream fs = new FileStream(file, FileMode.Open))
using (BinaryReader tempReader = new BinaryReader(fs))
{
AddWriter.Write(tempReader.ReadBytes((int)fs.Length));
}
File.Delete(file);
}
AddWriter.Close();
}
/// <summary>
/// 获取文件大小
/// </summary>
/// <returns></returns>
private long GetFileSize()
{
FtpWebRequest ftpRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri(RequestPath));
ftpRequest.Method = WebRequestMethods.Ftp.GetFileSize;
ftpRequest.KeepAlive = false;
ftpRequest.UseBinary = true;
ftpRequest.Credentials = new NetworkCredential(_UserName, _Password);
FtpWebResponse response = (FtpWebResponse)ftpRequest.GetResponse();
return response.ContentLength;
}
#endregion
}
}