问题描述
我正在使用 Filestream 读取大文件 (> 500 MB)，但出现 OutOfMemoryException.
I'm using Filestream for read big file (> 500 MB) and I get the OutOfMemoryException.
我使用 Asp.net、.net 3.5、win2003、iis 6.0
I use Asp.net , .net 3.5, win2003, iis 6.0
我希望在我的应用中使用这个:
I want this in my app:
从 Oracle 读取数据
Read DATA from Oracle
使用 FileStream 和 BZip2 解压缩文件
Uncompress file using FileStream and BZip2
读取未压缩的文件并将其发送到asp.net页面进行下载.
Read file uncompressed and send it to asp.net page for download.
当我从磁盘读取文件时，失败！！！并获得 OutOfMemory...
When I read file from disk, Fails !!! and get OutOfMemory...
.我的代码是:
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;
}
现在，我更好地说明了我的问题.
Now, I specify my issue better.
使用 FileStream 和 BZip2 解压文件就可以了，一切正常.
Uncompress file using FileStream and BZip2 is OK, all is right.
问题如下:
以字节[]读取磁盘中的胖大文件(> 500 MB)并将字节发送到响应(asp.net)以进行下载.
Read fat big file in disk (> 500 MB) in byte[] and send bytes to Response (asp.net) for download it.
使用时
http://www.yoda.arachsys.com/csharp/readbinary.html
public static byte[] ReadFully
我收到错误:OutOfMemoryException...
I get the error: OutOfMemoryException...
如果 BufferedStream 比 Stream (FileStream, MemoryStream, ...) 更好 ??
If better BufferedStream than Stream (FileStream, MemoryStream, ...) ??
使用 BufferedStream ，我可以读取 700 MB 的大文件吗??(任何使用 BufferedStream 下载大文件的示例代码源)
Using BufferedStream , Can I read big file of 700 MB ?? (any sample code source using BufferedStream for download big file)
我认为，问题是:不是如何将 500mb 的文件读入内存?", 但是如何将大文件发送到 ASPNET 响应流?"
I think, this is the question: Not "how to read a 500mb file into memory?" , But "how to send a large file to the ASPNET Response stream?"
我找到了 Cheeso 的代码:
I found this code by Cheeso:
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);
}
}
这是好的代码吗??对高性能有什么改进吗??
Is it good code ?? any improvements for high performance ??
同事说我，用
Response.TransmitFile(filePath);
现在，另一个问题，更好的 TransmitFile 或 Cheeso 代码 ??
Now, another question, better TransmitFile or code by Cheeso ??
许多年前，在 msdn 杂志上出现了关于它的很棒的文章，但我无法访问 http://msdn.microsoft.com/msdnmag/issues/06/09/WebDownloads/,
Many years ago, in msdn magazine appears great article about it but I cannot access http://msdn.microsoft.com/msdnmag/issues/06/09/WebDownloads/,
更新:您可以在链接中使用 webarchive 访问:https://web.archive.org/web/20070627063111/http://msdn.microsoft.com/msdnmag/issues/06/09/WebDownloads/
Update: You can access using webarchive in the link: 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??
Any suggestions, comments, sample code source??
推荐答案
几个月前我创建了下载页面，允许用户下载高达 4gb(可能更多).这是我的工作片段:
I've created download page which allows user to download up to 4gb (may be more) few months ago. Here is my working snippet:
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();
}
}
这篇关于使用 FileStream ASPNET 发送 500MB 大文件时出现 OutOfMemoryException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！