使用FileStream ASPNET发送大文件500MB时出现OutOfMemoryException

Question

我正在使用Filestream读取大文件(> 500 MB),我得到了OutOfMemoryException.

我使用Asp.net,.net 3.5,win2003,iis 6.0

我希望在我的应用中:

Read DATA from Oracle

Uncompress file using FileStream and BZip2

Read file uncompressed and send it to asp.net page for download.

When I read file from disk, Fails !!! and get OutOfMemory...

. My Code is:

using (var fs3 = new FileStream(filePath2, FileMode.Open, FileAccess.Read)) 
        { 
          byte[] b2 = ReadFully(fs3, 1024); 
        } 

 // http://www.yoda.arachsys.com/csharp/readbinary.html
 public static byte[] ReadFully(Stream stream, int initialLength) 
  { 
    // If we've been passed an unhelpful initial length, just 
    // use 32K. 
    if (initialLength < 1) 
    { 
      initialLength = 32768; 
    } 

    byte[] buffer = new byte[initialLength]; 
    int read = 0; 

    int chunk; 
    while ((chunk = stream.Read(buffer, read, buffer.Length - read)) > 0) 
    { 
      read += chunk; 

      // If we've reached the end of our buffer, check to see if there's 
      // any more information 
      if (read == buffer.Length) 
      { 
        int nextByte = stream.ReadByte(); 

        // End of stream? If so, we're done 
        if (nextByte == -1) 
        { 
          return buffer; 
        } 

        // Nope. Resize the buffer, put in the byte we've just 
        // read, and continue 
        byte[] newBuffer = new byte[buffer.Length * 2]; 
        Array.Copy(buffer, newBuffer, buffer.Length); 
        newBuffer[read] = (byte)nextByte; 
        buffer = newBuffer; 
        read++; 
      } 
    } 
    // Buffer is now too big. Shrink it. 
    byte[] ret = new byte[read]; 
    Array.Copy(buffer, ret, read); 
    return ret; 
  } 

Now, I specify my issue better.

Uncompress file using FileStream and BZip2 is OK, all is right.

The Problem is the following:

Read fat big file in disk (> 500 MB) in byte[] and send bytes to Response (asp.net) for download it.

When use

http://www.yoda.arachsys.com/csharp/readbinary.html

public static byte[] ReadFully

I get the error: OutOfMemoryException...

If better BufferedStream than Stream (FileStream, MemoryStream, ...) ??

Using BufferedStream , Can I read big file of 700 MB ?? (any sample code source using BufferedStream for download big file)

我想,这是一个问题:不是"如何将500mb文件读入内存？" ,但"如何将大文件发送到ASPNET响应流？"

我在Cheeso找到了这个代码:

using (var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))  
{  
   Response.BufferOutput= false;   // to prevent buffering 
   byte[] buffer = new byte[1024]; 
   int bytesRead = 0; 
   while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) > 0)  
   { 
       Response.OutputStream.Write(buffer, 0, bytesRead); 
   } 
}

好的代码？高性能的任何改进？

一位同事说我,用

Response.TransmitFile(filePath);

现在,另一个问题,更好的TransmitFile或Cheeso的代码？

很多年前,在msdn杂志上看起来很棒的文章,但我无法访问http://msdn.microsoft.com/msdnmag/issues/06/09/WebDownloads/,

更新:您可以通过以下链接访问webarchive:https://web.archive.org/web/20070627063111/http://msdn.microsoft.com/msdnmag/issues/06/09/WebDownloads/

任何建议,评论,示例代码源？

Answer 1

我创建了下载页面,允许用户在几个月前下载高达4GB(可能更多).这是我的工作片段:

  private void TransmitFile(string fullPath, string outFileName)
    {
        System.IO.Stream iStream = null;

        // Buffer to read 10K bytes in chunk:
        byte[] buffer = new Byte[10000];

        // Length of the file:
        int length;

        // Total bytes to read:
        long dataToRead;

        // Identify the file to download including its path.
        string filepath = fullPath;

        // 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);


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

            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=" + outFileName);
            Response.AddHeader("Content-Length", iStream.Length.ToString());

            // Read the bytes.
            while (dataToRead > 0)
            {
                // Verify that the client is connected.
                if (Response.IsClientConnected)
                {
                    // Read the data in buffer.
                    length = iStream.Read(buffer, 0, 10000);

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

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

                    buffer = new Byte[10000];
                    dataToRead = dataToRead - length;
                }
                else
                {
                    //prevent infinite loop if user disconnects
                    dataToRead = -1;
                }
            }
        }
        catch (Exception ex)
        {
            throw new ApplicationException(ex.Message);
        }
        finally
        {
            if (iStream != null)
            {
                //Close the file.
                iStream.Close();
            }
            Response.Close();
        }
    }