我正在使用以下代码上传文件：
https://gist.github.com/bgrins/1789787
但是，如果我尝试使用此代码上传文件“ 2 GB”文件，则会出现内存不足异常以及此行中的原因：
https://gist.github.com/bgrins/1789787#file-gistfile1-cs-L75
那我该如何解决这个问题？
答案 0 :(得分：2)
逐个读取巨型文件，然后逐个上传。您也可以提供进度条。
您可以使用此想法详细说明代码。我去年做过一次，但是不能共享代码。
答案 1 :(得分：1)
有不止一种解决方案
1-直接写入RequestStream而不是写入MemoryStream：
public static string MyUploader(string strFileToUpload, string strUrl)
{
string strFileFormName = "file";
Uri oUri = new Uri(strUrl);
string strBoundary = "----------" + DateTime.Now.Ticks.ToString("x");
// The trailing boundary string
byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + strBoundary + "\r\n");
// The post message header
StringBuilder sb = new StringBuilder();
sb.Append("--");
sb.Append(strBoundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"");
sb.Append(strFileFormName);
sb.Append("\"; filename=\"");
sb.Append(Path.GetFileName(strFileToUpload));
sb.Append("\"");
sb.Append("\r\n");
sb.Append("Content-Type: ");
sb.Append("application/octet-stream");
sb.Append("\r\n");
sb.Append("\r\n");
string strPostHeader = sb.ToString();
byte[] postHeaderBytes = Encoding.UTF8.GetBytes(strPostHeader);
// The WebRequest
HttpWebRequest oWebrequest = (HttpWebRequest)WebRequest.Create(oUri);
oWebrequest.ContentType = "multipart/form-data; boundary=" + strBoundary;
oWebrequest.Method = "POST";
// This is important, otherwise the whole file will be read to memory anyway...
oWebrequest.AllowWriteStreamBuffering = false;
// Get a FileStream and set the final properties of the WebRequest
FileStream oFileStream = new FileStream(strFileToUpload, FileMode.Open, FileAccess.Read);
long length = postHeaderBytes.Length + oFileStream.Length + boundaryBytes.Length;
oWebrequest.ContentLength = length;
Stream oRequestStream = oWebrequest.GetRequestStream();
// Write the post header
oRequestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
// Stream the file contents in small pieces (4096 bytes, max).
byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)oFileStream.Length))];
int bytesRead = 0;
while ((bytesRead = oFileStream.Read(buffer, 0, buffer.Length)) != 0)
oRequestStream.Write(buffer, 0, bytesRead);
oFileStream.Close();
// Add the trailing boundary
oRequestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
WebResponse oWResponse = oWebrequest.GetResponse();
Stream s = oWResponse.GetResponseStream();
StreamReader sr = new StreamReader(s);
String sReturnString = sr.ReadToEnd();
// Clean up
oFileStream.Close();
oRequestStream.Close();
s.Close();
sr.Close();
return sReturnString;
}
2-使用RecyclableMemoryStream代替MemoryStream解决方案
您可以在此处阅读有关RecyclableMemoryStream的更多信息： http://www.philosophicalgeek.com/2015/02/06/announcing-microsoft-io-recycablememorystream/
https://github.com/Microsoft/Microsoft.IO.RecyclableMemoryStream
3-使用MemoryTributary代替MemoryStream
您可以在此处阅读有关MemoryTributary的更多信息：
https://www.codeproject.com/Articles/348590/A-replacement-for-MemoryStream?msg=5257615#xx5257615xx
using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
namespace LiquidEngine.Tools
{
/// <summary>
/// MemoryTributary is a re-implementation of MemoryStream that uses a dynamic list of byte arrays as a backing store, instead of a single byte array, the allocation
/// of which will fail for relatively small streams as it requires contiguous memory.
/// </summary>
public class MemoryTributary : Stream /* http://msdn.microsoft.com/en-us/library/system.io.stream.aspx */
{
#region Constructors
public MemoryTributary()
{
Position = 0;
}
public MemoryTributary(byte[] source)
{
this.Write(source, 0, source.Length);
Position = 0;
}
/* length is ignored because capacity has no meaning unless we implement an artifical limit */
public MemoryTributary(int length)
{
SetLength(length);
Position = length;
byte[] d = block; //access block to prompt the allocation of memory
Position = 0;
}
#endregion
#region Status Properties
public override bool CanRead
{
get { return true; }
}
public override bool CanSeek
{
get { return true; }
}
public override bool CanWrite
{
get { return true; }
}
#endregion
#region Public Properties
public override long Length
{
get { return length; }
}
public override long Position { get; set; }
#endregion
#region Members
protected long length = 0;
protected long blockSize = 65536;
protected List<byte[]> blocks = new List<byte[]>();
#endregion
#region Internal Properties
/* Use these properties to gain access to the appropriate block of memory for the current Position */
/// <summary>
/// The block of memory currently addressed by Position
/// </summary>
protected byte[] block
{
get
{
while (blocks.Count <= blockId)
blocks.Add(new byte[blockSize]);
return blocks[(int)blockId];
}
}
/// <summary>
/// The id of the block currently addressed by Position
/// </summary>
protected long blockId
{
get { return Position / blockSize; }
}
/// <summary>
/// The offset of the byte currently addressed by Position, into the block that contains it
/// </summary>
protected long blockOffset
{
get { return Position % blockSize; }
}
#endregion
#region Public Stream Methods
public override void Flush()
{
}
public override int Read(byte[] buffer, int offset, int count)
{
long lcount = (long)count;
if (lcount < 0)
{
throw new ArgumentOutOfRangeException("count", lcount, "Number of bytes to copy cannot be negative.");
}
long remaining = (length - Position);
if (lcount > remaining)
lcount = remaining;
if (buffer == null)
{
throw new ArgumentNullException("buffer", "Buffer cannot be null.");
}
if (offset < 0)
{
throw new ArgumentOutOfRangeException("offset",offset,"Destination offset cannot be negative.");
}
int read = 0;
long copysize = 0;
do
{
copysize = Math.Min(lcount, (blockSize - blockOffset));
Buffer.BlockCopy(block, (int)blockOffset, buffer, offset, (int)copysize);
lcount -= copysize;
offset += (int)copysize;
read += (int)copysize;
Position += copysize;
} while (lcount > 0);
return read;
}
public override long Seek(long offset, SeekOrigin origin)
{
switch (origin)
{
case SeekOrigin.Begin:
Position = offset;
break;
case SeekOrigin.Current:
Position += offset;
break;
case SeekOrigin.End:
Position = Length - offset;
break;
}
return Position;
}
public override void SetLength(long value)
{
length = value;
}
public override void Write(byte[] buffer, int offset, int count)
{
long initialPosition = Position;
int copysize;
try
{
do
{
copysize = Math.Min(count, (int)(blockSize - blockOffset));
EnsureCapacity(Position + copysize);
Buffer.BlockCopy(buffer, (int)offset, block, (int)blockOffset, copysize);
count -= copysize;
offset += copysize;
Position += copysize;
} while (count > 0);
}
catch (Exception e)
{
Position = initialPosition;
throw e;
}
}
public override int ReadByte()
{
if (Position >= length)
return -1;
byte b = block[blockOffset];
Position++;
return b;
}
public override void WriteByte(byte value)
{
EnsureCapacity(Position + 1);
block[blockOffset] = value;
Position++;
}
protected void EnsureCapacity(long intended_length)
{
if (intended_length > length)
length = (intended_length);
}
#endregion
#region IDispose
/* http://msdn.microsoft.com/en-us/library/fs2xkftw.aspx */
protected override void Dispose(bool disposing)
{
/* We do not currently use unmanaged resources */
base.Dispose(disposing);
}
#endregion
#region Public Additional Helper Methods
/// <summary>
/// Returns the entire content of the stream as a byte array. This is not safe because the call to new byte[] may
/// fail if the stream is large enough. Where possible use methods which operate on streams directly instead.
/// </summary>
/// <returns>A byte[] containing the current data in the stream</returns>
public byte[] ToArray()
{
long firstposition = Position;
Position = 0;
byte[] destination = new byte[Length];
Read(destination, 0, (int)Length);
Position = firstposition;
return destination;
}
/// <summary>
/// Reads length bytes from source into the this instance at the current position.
/// </summary>
/// <param name="source">The stream containing the data to copy</param>
/// <param name="length">The number of bytes to copy</param>
public void ReadFrom(Stream source, long length)
{
byte[] buffer = new byte[4096];
int read;
do
{
read = source.Read(buffer, 0, (int)Math.Min(4096, length));
length -= read;
this.Write(buffer, 0, read);
} while (length > 0);
}
/// <summary>
/// Writes the entire stream into destination, regardless of Position, which remains unchanged.
/// </summary>
/// <param name="destination">The stream to write the content of this stream to</param>
public void WriteTo(Stream destination)
{
long initialpos = Position;
Position = 0;
this.CopyTo(destination);
Position = initialpos;
}
#endregion
}
}