多线程下载类
namespace JH.Framework.Threads
{
/// <summary>
/// 多线程下载类
///
/// </summary>
public class MultiDownload
{
#region 变量
private int _threadNum; //线程数量
private long _fileSize; //文件大小
private string _extName; //文件扩展名
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
public string FileName
{
get
{
return _fileName;
}
set
{
_fileName = value;
}
}
public long FileSize
{
get
{
return _fileSize;
}
}
public int DownloadSize
{
get
{
return _downloadSize;
}
}
public bool IsComplete
{
get
{
return _isComplete;
}
}
public int ThreadNum
{
get
{
return _threadNum;
}
}
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();
_extName = response.ResponseUri.ToString().Substring(response.ResponseUri.ToString().LastIndexOf('.'));//获取真实扩展名
_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);
_thread[i] = new Thread(() => { Download(range[0], range[1]); });
_thread[i].Name = "jhxz_{0}".Formats(i + 1);
_thread[i].Start();
}
}
private void Download(int from, int to)
{
Stream httpFileStream = null, localFileStram = null;
try
{
string tmpFileBlock = @"{0}\{1}_{2}.dat".Formats(_savePath, _fileName, Thread.CurrentThread.Name);
_tempFiles.Add(tmpFileBlock);
HttpWebRequest httprequest = (HttpWebRequest)WebRequest.Create(_fileUrl);
httprequest.AddRange(from, to);
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(@"{0}\{1}{2}".Formats(_savePath, _fileName, _extName), 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();
}
}
}