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C# FileStream实现多线程断点续传

一、前言

       网上有许多的多线程 断点续传 操作,但总是写的很云里雾里,或者写的比较坑长。由于这几个月要负责公司的在线升级项目,所以正好顺便写了一下

代码如下:

?

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;

    }

   }

  }

}

二、讨论      

1)需要注意的是第44行,不能直接使用index变量在Task()里进行操作,而是要将它赋给Threadindex,让Threadindex在Task()里,不然会直接报错,为什么呢? 查看链接

2)70至108行代码可以在外面再套一层while循环,循环检测临时文件是否下完整了,然后再定义一个检测最大上限,超过这个上限就放弃本次更新,当用户的网络恢复正常后下次再做更新操作。所以说放临时文件的文件夹最好要包含版本信息,不会把2.0.0的临时文件和1.0.0的临时文件搞混。

3) FileStream.Position 与 FileStream.Seek(long offset, SeekOrigin seekorigin) 的作用都是获取流的指针位置,当文件路径使用绝对路径时使用Position;相对路径时使用Seek方法, 查看链接

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。

原文链接:http://HdhCmsTestcnblogs测试数据/lovecsharp094/p/5727141.html

dy("nrwz");

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