本文介绍了下载功能大的文件大小失败的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
大家好，我下载的功能。
Hi my download function.
protected void downloadFunction(string fileName)
{
string filePath = @"D:\SoftwareFiles\";
LogMessageToFile("Download started " + filePath + fileName);
byte[] array = File.ReadAllBytes(filePath + fileName);
Response.Clear();
Response.ContentType = "application/x-newton-compatible-pkg";
Response.AppendHeader("Content-Disposition",
"attachment;filename=" + fileName);
Response.BinaryWrite(array);
Response.End();
}
在处理文件大小20，200MB没有问题的。
When handling filesize of 20, 200mb no problem.
在处理1GB的文件，则抛出异常：
When handling 1gb file, an exception is thrown:
溢出或下溢在算术运算。
说明：当前Web请求的执行过程中发生未处理的异常。请查看有关错误的详细堆栈跟踪信息，以及它起源于code。
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
异常详细信息：System.ArithmeticException：溢出或下溢的算术运算
Exception Details: System.ArithmeticException: Overflow or underflow in the arithmetic operation.
怎么办？
推荐答案
我的猜测是，你正在运行内存在 byte []数组。
My guess is that you're running out of memory in the byte[] array.
您可以尝试打破文件下来，读它的块。
You can try breaking the file down and reading it in chunks.
我发现了一个code例如从谷歌搜索，让你开始：
I found a code example from a Google search to get you started:
C＃文件下载AKA Response.BinaryWrite
using System;
using System.IO;
using System.Web;
public class Download
{
public static void SmallFile(string filename, string filepath, string contentType)
{
try
{
FileStream MyFileStream = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
long FileSize;
FileSize = MyFileStream.Length;
byte[] Buffer = new byte[(int)FileSize];
MyFileStream.Read(Buffer, 0, (int)MyFileStream.Length);
MyFileStream.Close();
HttpContext.Current.Response.ContentType = contentType;
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
HttpContext.Current.Response.BinaryWrite(Buffer);
}
catch
{
HttpContext.Current.Response.ContentType = "text/html";
HttpContext.Current.Response.Write("Downloading Error!");
}
HttpContext.Current.Response.End();
}
public static void LargeFile(string filename, string filepath, string contentType)
{
Stream iStream = null;
// Buffer to read 10K bytes in chunk
//byte[] buffer = new Byte[10000];
// Buffer to read 1024K bytes in chunk
byte[] buffer = new Byte[1048576];
// Length of the file:
int length;
// Total bytes to read:
long dataToRead;
try
{
// Open the file.
iStream = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
// Total bytes to read:
dataToRead = iStream.Length;
HttpContext.Current.Response.ContentType = contentType;
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
// Read the bytes.
while (dataToRead > 0)
{
// Verify that the client is connected.
if (HttpContext.Current.Response.IsClientConnected)
{
// Read the data in buffer.
length = iStream.Read(buffer, 0, 10000);
// Write the data to the current output stream.
HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);
// Flush the data to the HTML output.
HttpContext.Current.Response.Flush();
buffer = new Byte[10000];
dataToRead = dataToRead - length;
}
else
{
//prevent infinite loop if user disconnects
dataToRead = -1;
}
}
}
catch (Exception ex)
{
// Trap the error, if any.
//HttpContext.Current.Response.Write("Error : " + ex.Message);
HttpContext.Current.Response.ContentType = "text/html";
HttpContext.Current.Response.Write("Error : file not found");
}
finally
{
if (iStream != null)
{
//Close the file.
iStream.Close();
}
HttpContext.Current.Response.End();
HttpContext.Current.Response.Close();
}
}
public static void ResumableFile(string filename, string fullpath, string contentType)
{
try
{
FileStream myFile = new FileStream(fullpath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
BinaryReader br = new BinaryReader(myFile);
try
{
HttpContext.Current.Response.AddHeader("Accept-Ranges", "bytes");
HttpContext.Current.Response.Buffer = false;
long fileLength = myFile.Length;
long startBytes = 0;
//int pack = 10240; //10K bytes
int pack = 1048576; //1024K bytes
if (HttpContext.Current.Request.Headers["Range"] != null)
{
HttpContext.Current.Response.StatusCode = 206;
string[] range = HttpContext.Current.Request.Headers["Range"].Split(new char[] { '=', '-' });
startBytes = Convert.ToInt64(range[1]);
}
HttpContext.Current.Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
if (startBytes != 0)
{
HttpContext.Current.Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
}
HttpContext.Current.Response.AddHeader("Connection", "Keep-Alive");
HttpContext.Current.Response.ContentType = contentType;
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
int maxCount = (int)Math.Floor((double)((fileLength - startBytes) / pack)) + 1;
for (int i = 0; i < maxCount; i++)
{
if (HttpContext.Current.Response.IsClientConnected)
{
HttpContext.Current.Response.BinaryWrite(br.ReadBytes(pack));
}
else
{
i = maxCount;
}
}
}
catch
{
HttpContext.Current.Response.ContentType = "text/html";
HttpContext.Current.Response.Write("Error : file not found");
}
finally
{
br.Close();
myFile.Close();
}
}
catch
{
HttpContext.Current.Response.ContentType = "text/html";
HttpContext.Current.Response.Write("Error : file not found");
}
}
}
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