文件下载

文件下载

   
     

    
      
    
      public
    
       
    
      static
    
       
    
      bool
    
       ResponseFile(HttpRequest _Request, HttpResponse _Response, 
    
      string
    
       _fileName, 
    
      string
    
       _fullPath, 
    
      long
    
       _speed)
 {
 
    
      try
    
      
 {
 FileStream myFile 
    
      =
    
       
    
      new
    
       FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
 BinaryReader br 
    
      =
    
       
    
      new
    
       BinaryReader(myFile);
 
    
      try
    
      
 {
 _Response.AddHeader(
    
      "
    
      Accept-Ranges
    
      "
    
      , 
    
      "
    
      bytes
    
      "
    
      );
 _Response.Buffer 
    
      =
    
       
    
      false
    
      ;
 
    
      long
    
       fileLength 
    
      =
    
       myFile.Length;
 
    
      long
    
       startBytes 
    
      =
    
       
    
      0
    
      ;

 
    
      double
    
       pack 
    
      =
    
       
    
      10240
    
      ; 
    
      //
    
      10K bytes
 
    
      //
    
      int sleep = 200; 
    
      //
    
      每秒5次 即5*10K bytes每秒
    
      

    
       
    
      int
    
       sleep 
    
      =
    
       (
    
      int
    
      )Math.Floor(
    
      1000
    
       
    
      *
    
       pack 
    
      /
    
       _speed) 
    
      +
    
       
    
      1
    
      ;
 
    
      if
    
       (_Request.Headers[
    
      "
    
      Range
    
      "
    
      ] 
    
      !=
    
       
    
      null
    
      )
 {
 _Response.StatusCode 
    
      =
    
       
    
      206
    
      ;
 
    
      string
    
      [] range 
    
      =
    
       _Request.Headers[
    
      "
    
      Range
    
      "
    
      ].Split(
    
      new
    
       
    
      char
    
      [] { 
    
      '
    
      =
    
      '
    
      , 
    
      '
    
      -
    
      '
    
       });
 startBytes 
    
      =
    
       Convert.ToInt64(range[
    
      1
    
      ]);
 }
 _Response.AddHeader(
    
      "
    
      Content-Length
    
      "
    
      , (fileLength 
    
      -
    
       startBytes).ToString());
 
    
      if
    
       (startBytes 
    
      !=
    
       
    
      0
    
      )
 {
 
    
      //
    
      Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength-1, fileLength));
    
      

    
       }
 _Response.AddHeader(
    
      "
    
      Connection
    
      "
    
      , 
    
      "
    
      Keep-Alive
    
      "
    
      );
 _Response.ContentType 
    
      =
    
       
    
      "
    
      application/octet-stream;charset=gbk
    
      "
    
      ;
 _Response.AddHeader(
    
      "
    
      Content-Disposition
    
      "
    
      , 
    
      "
    
      attachment;filename=
    
      "
    
       
    
      +
    
       HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

 br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
 
    
      int
    
       maxCount 
    
      =
    
       (
    
      int
    
      )Math.Floor((fileLength 
    
      -
    
       startBytes) 
    
      /
    
       pack) 
    
      +
    
       
    
      1
    
      ;

 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       maxCount; i
    
      ++
    
      )
 {
 
    
      if
    
       (_Response.IsClientConnected)
 {
 _Response.BinaryWrite(br.ReadBytes(
    
      int
    
      .Parse(pack.ToString())));
 Thread.Sleep(sleep);
 }
 
    
      else
    
      
 {
 i 
    
      =
    
       maxCount;
 }
 }
 }
 
    
      catch
    
      
 {
 
    
      return
    
       
    
      false
    
      ;
 }
 
    
      finally
    
      
 {
 br.Close();

 myFile.Close();
 }
 }
 
    
      catch
    
      
 {
 
    
      return
    
       
    
      false
    
      ;
 }
 
    
      return
    
       
    
      true
    
      ;
 }
   
     

调用方法

   
     

    
      
    
       ExportExcel excel 
    
      =
    
       
    
      new
    
       ExportExcel();

    
      string
    
       fileName 
    
      =
    
       excel.Export(dt, 
    
      "
    
      项目统计
    
      "
    
      , DataName);

    
      string
    
       path 
    
      =
    
       Request.PhysicalApplicationPath 
    
      +
    
       
    
      "
    
      Excel\\
    
      "
    
       
    
      +
    
       fileName 
    
      +
    
       
    
      "
    
      .xls
    
      "
    
      ;
DownFile.ResponseFile(Page.Request, Page.Response, fileName 
    
      +
    
       
    
      "
    
      .xls
    
      "
    
      , path, 
    
      1024000
    
      );
   
     

没搞清楚到底是什么原理，留下，等以后研究。