C# FileStream实现多线程断点续传

using System;using System.Collections.Generic;using System.IO;using System.Threading.Tasks;namespace TestCenter{ class Program {  static void Main(string[] args)  {   string LocalSavePath = @"E:/Test/TestFile/Local/1.msi"; //本地目标文件路径   FileInfo SeverFilePath = new FileInfo(@"E:/Test/TestFile/Server/1.msi"); //服务器待文件路径   long FileLength = SeverFilePath.Length; //待下载文件大小   Console.WriteLine("Start Configuration");   int PackCount = 0; //初始化数据包个数   long PackSize = 1024000; //数据包大小   if (FileLength % PackSize > 0)   {    PackCount = (int)(FileLength / PackSize) + 1;   }   else   {    PackCount = (int)(FileLength / PackSize);   }   Console.WriteLine("Start Recieve");   var tasks = new Task[PackCount]; //多线程任务   for (int index = 0; index < PackCount; index++)   {    int Threadindex = index; //这步很关键，在Task()里的绝对不能直接使用index    var task = new Task(() =>    {     string tempfilepath = @"E:/Test/TestFile/Temp/" + "QS_" + Threadindex + "_" + PackCount; //临时文件路径     using (FileStream tempstream = new FileStream(tempfilepath, FileMode.Create, FileAccess.Write, FileShare.Write))     {      int length = (int)Math.Min(PackSize, FileLength - Threadindex * PackSize);      var bytes = GetFile(Threadindex*PackCount, length);      tempstream.Write(bytes, 0, length);      tempstream.Flush();      tempstream.Close();      tempstream.Dispose();     }    });    tasks[Threadindex] = task;    task.Start();   }   Task.WaitAll(tasks); //等待所有线程完成   Console.WriteLine("Recieve End");   //检测有哪些数据包未下载   Console.WriteLine("Start Compare");   DirectoryInfo TempDir = new DirectoryInfo(@"E:/Test/TestFile/temp"); //临时文件夹路径   List<string> Comparefiles = new List<string>();   for (int i = 0; i < PackCount; i++)   {    bool hasfile = false;    foreach (FileInfo Tempfile in TempDir.GetFiles())    {     if (Tempfile.Name.Split('_')[1] == i.ToString())     {      hasfile = true;      break;     }    }    if (hasfile == false)    {     Comparefiles.Add(i.ToString());    }   }   //最后补上这些缺失的文件   if (Comparefiles.Count > 0)   {    foreach (string com_index in Comparefiles)    {     string tempfilepath = @"E:/Test/TestFile/Temp/" + "QS_" + com_index+ "_" + PackCount;     using (FileStream Compstream = new FileStream(tempfilepath, FileMode.Create, FileAccess.Write, FileShare.Write))     {      int length = (int)Math.Min(PackSize, FileLength - Convert.ToInt32(com_index) * PackSize);      var bytes = GetFile(Convert.ToInt32(com_index)*PackCount, length);      Compstream.Write(bytes, 0, length);      Compstream.Flush();      Compstream.Close();      Compstream.Dispose();     }    }   }   Console.WriteLine("Compare End");   //准备将临时文件融合并写到1.msi中   Console.WriteLine("Start Write");   using (FileStream writestream = new FileStream(LocalSavePath, FileMode.Create, FileAccess.Write, FileShare.Write))   {    foreach (FileInfo Tempfile in TempDir.GetFiles())    {     using (FileStream readTempStream = new FileStream(Tempfile.FullName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))     {      long onefileLength = Tempfile.Length;      byte[] buffer = new byte[Convert.ToInt32(onefileLength)];      readTempStream.Read(buffer, 0, Convert.ToInt32(onefileLength));      writestream.Write(buffer, 0, Convert.ToInt32(onefileLength));     }    }    writestream.Flush();    writestream.Close();    writestream.Dispose();   }   Console.WriteLine("Write End");   //删除临时文件   Console.WriteLine("Start Delete Temp Files");   foreach (FileInfo Tempfile in TempDir.GetFiles())   {    Tempfile.Delete();   }   Console.WriteLine("Delete Success");   Console.ReadKey();  }  //这个方法可以放到Remoting或者WCF服务中去，然后本地调用该方法即可实现多线程断点续传  public static byte[] GetFile(int start, int length)  {   string SeverFilePath = @"E:/Test/TestFile/Server/1.msi";   using (FileStream ServerStream = new FileStream(SeverFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, 1024*80, true))   {    byte[] buffer = new byte[length];    ServerStream.Position = start;    //ServerStream.Seek(start, SeekOrigin.Begin);    ServerStream.Read(buffer, 0, length);    return buffer;   }  } }}