C#实现多线程下载文件的方法

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.IO;using System.Threading;using System.Net;namespace WfpApp{ public class MultiDownload {  #region 变量  private int _threadNum;    //线程数量  private long _fileSize;    //文件大小  private string _fileUrl;   //文件地址  private string _fileName;   //文件名  private string _savePath;   //保存路径  private short _threadCompleteNum; //线程完成数量  private bool _isComplete;   //是否完成  private volatile int _downloadSize; //当前下载大小(实时的)  private Thread[] _thread;   //线程数组  private List<string> _tempFiles = new List<string>();  private object locker = new object();  #endregion  #region 属性  /// <summary>  /// 文件名  /// </summary>  public string FileName  {   get   {    return _fileName;   }   set   {    _fileName = value;   }  }  /// <summary>  /// 文件大小  /// </summary>  public long FileSize  {   get   {    return _fileSize;   }  }  /// <summary>  /// 当前下载大小(实时的)  /// </summary>  public int DownloadSize  {   get   {    return _downloadSize;   }  }  /// <summary>  /// 是否完成  /// </summary>  public bool IsComplete  {   get   {    return _isComplete;   }  }  /// <summary>  /// 线程数量  /// </summary>  public int ThreadNum  {   get   {    return _threadNum;   }  }  /// <summary>  /// 保存路径  /// </summary>  public string SavePath  {   get   {    return _savePath;   }   set   {    _savePath = value;   }  }  #endregion  /// <summary>  /// 构造函数  /// </summary>  /// <param name="threahNum">线程数量</param>  /// <param name="fileUrl">文件Url路径</param>  /// <param name="savePath">本地保存路径</param>  public MultiDownload(int threahNum, string fileUrl, string savePath)  {   this._threadNum = threahNum;   this._thread = new Thread[threahNum];   this._fileUrl = fileUrl;   this._savePath = savePath;  }  public void Start()  {   HttpWebRequest request = (HttpWebRequest)WebRequest.Create(_fileUrl);   HttpWebResponse response = (HttpWebResponse)request.GetResponse();   _fileSize = response.ContentLength;   int singelNum = (int)(_fileSize / _threadNum);  //平均分配   int remainder = (int)(_fileSize % _threadNum);  //获取剩余的   request.Abort();   response.Close();   for (int i = 0; i < _threadNum; i++)   {    List<int> range = new List<int>();    range.Add(i * singelNum);    if (remainder != 0 && (_threadNum - 1) == i) //剩余的交给最后一个线程     range.Add(i * singelNum + singelNum + remainder - 1);    else     range.Add(i * singelNum + singelNum - 1);    //下载指定位置的数据    int[] ran = new int[] { range[0], range[1] };    _thread[i] = new Thread(new ParameterizedThreadStart(Download));    _thread[i].Name = System.IO.Path.GetFileNameWithoutExtension(_fileUrl) + "_{0}".Replace("{0}", Convert.ToString(i + 1));    _thread[i].Start(ran);   }  }  private void Download(object obj)  {   Stream httpFileStream = null, localFileStram = null;   try   {    int[] ran = obj as int[];    string tmpFileBlock = System.IO.Path.GetTempPath() + Thread.CurrentThread.Name + ".tmp";    _tempFiles.Add(tmpFileBlock);    HttpWebRequest httprequest = (HttpWebRequest)WebRequest.Create(_fileUrl);    httprequest.AddRange(ran[0], ran[1]);    HttpWebResponse httpresponse = (HttpWebResponse)httprequest.GetResponse();    httpFileStream = httpresponse.GetResponseStream();    localFileStram = new FileStream(tmpFileBlock, FileMode.Create);    byte[] by = new byte[5000];    int getByteSize = httpFileStream.Read(by, 0, (int)by.Length); //Read方法将返回读入by变量中的总字节数    while (getByteSize > 0)    {     Thread.Sleep(20);     lock (locker) _downloadSize += getByteSize;     localFileStram.Write(by, 0, getByteSize);     getByteSize = httpFileStream.Read(by, 0, (int)by.Length);    }    lock (locker) _threadCompleteNum++;   }   catch (Exception ex)   {    throw new Exception(ex.Message.ToString());   }   finally   {    if (httpFileStream != null) httpFileStream.Dispose();    if (localFileStram != null) localFileStram.Dispose();   }   if (_threadCompleteNum == _threadNum)   {    Complete();    _isComplete = true;   }  }  /// <summary>  /// 下载完成后合并文件块  /// </summary>  private void Complete()  {   Stream mergeFile = new FileStream(@_savePath, FileMode.Create);   BinaryWriter AddWriter = new BinaryWriter(mergeFile);   foreach (string file in _tempFiles)   {    using (FileStream fs = new FileStream(file, FileMode.Open))    {     BinaryReader TempReader = new BinaryReader(fs);     AddWriter.Write(TempReader.ReadBytes((int)fs.Length));     TempReader.Close();    }    File.Delete(file);   }   AddWriter.Close();  } }}

string httpUrl = @"http://172.28.98.96/fdimsservice/2.rar";string saveUrl = System.Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "//" + System.IO.Path.GetFileName(httpUrl);int threadNumber = 5;MultiDownload md = new MultiDownload(threadNumber, httpUrl, saveUrl);md.Start();