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Asp.net(c#)实现多线程断点续传

Posted on 2004-08-10 16:50 bestcomy 阅读(...) 评论(...) 编辑 收藏

以前一直错误的认为在ASP.NET中无法通过编程方式实现多线程断点续传,今天终于获得了这样一个解决方案,让我明白要学习的东西还很多
此解决方案基于其它解决方案及相关资料,根据我自己的理解改进.如有错漏,请尽管指出;如有其它更好的解决方案,请推荐一下,感谢先。

System.IO.Stream iStream = null;

            
// Buffer to read 10K bytes in chunk:
            byte[] buffer = new Byte[10240];

            
// Length of the file:
            int length;

            
// Total bytes to read:
            long dataToRead;

            
// Identify the file to download including its path.
            string filepath  = @"E:\software\SQL Server 2000 Personal Edition.ISO";

            
// Identify the file name.
            string  filename  = System.IO.Path.GetFileName(filepath);

            
try
            
{
                
// Open the file.
                iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open, 
                    System.IO.FileAccess.Read,System.IO.FileShare.Read);
                Response.Clear();

                
// Total bytes to read:
                dataToRead = iStream.Length;

                
long p = 0;
                
if(Request.Headers["Range"]!=null)
                
{
                    Response.StatusCode 
= 206;
                    p 
= long.Parse( Request.Headers["Range"].Replace("bytes=","").Replace("-",""));
                }

                
if(p != 0)
                
{
                    Response.AddHeader(
"Content-Range","bytes " + p.ToString() + "-" + ((long)(dataToRead - 1)).ToString() + "/" + dataToRead.ToString());                    
                }

                Response.AddHeader(
"Content-Length",((long)(dataToRead-p)).ToString());
                Response.ContentType 
= "application/octet-stream";
                Response.AddHeader(
"Content-Disposition""attachment; filename=" + System.Web.HttpUtility.UrlEncode(Request.ContentEncoding.GetBytes(filename)));

                iStream.Position 
= p;
                dataToRead 
= dataToRead - p;
                
// Read the bytes.
                while (dataToRead > 0)
                
{
                    
// Verify that the client is connected.
                    if (Response.IsClientConnected) 
                    
{
                        
// Read the data in buffer.
                        length = iStream.Read(buffer, 010240);

                        
// Write the data to the current output stream.
                        Response.OutputStream.Write(buffer, 0, length);

                        
// Flush the data to the HTML output.
                        Response.Flush();

                        buffer
= new Byte[10240];
                        dataToRead 
= dataToRead - length;
                    }

                    
else
                    
{
                        
//prevent infinite loop if user disconnects
                        dataToRead = -1;
                    }

                }

            }

            
catch (Exception ex) 
            
{
                
// Trap the error, if any.
                Response.Write("Error : " + ex.Message);
            }

            
finally
            
{
                
if (iStream != null
                
{
                    
//Close the file.
                    iStream.Close();
                }
                   Response.End();
            }


本解决方案所参考的资料链接列表(在此对作者表示感谢):
http://blog.csdn.net/playyuer/archive/2004/08/02/58430.aspx
http://www.httpsniffer.com/http/1416.htm
http://support.microsoft.com/default.aspx?scid=kb;en-us;812406&Product=aspnet

更新:
        此解决方案已根据playyuer 提出的问题作了更新,另外在输出前调用了Response.Clear();方法。