c# - 算术运算导致溢出错误-对于C#中的byte []数组

我在C＃中有这行：

    byte[] bytes = new byte[streamReader.BaseStream.Length];

该长度返回的文件大小大于4 GB。

在那一行我有以下错误：

Arithmetic operation resulted in an overflow.
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.

Exception Details: System.OverflowException: Arithmetic operation resulted in an overflow.

Source Error:


Line 41:             System.IO.BinaryReader br = new System.IO.BinaryReader(streamReader.BaseStream);
Line 42:
Line 43:             byte[] bytes = new byte[streamReader.BaseStream.Length];
Line 44:
Line 45:             br.Read(bytes, 0, (int)streamReader.BaseStream.Length);

我该如何解决此错误？

编辑
我正在使用.net 4
该代码是用于下载文件的处理程序的一部分，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using WindowsServer.Classes;

namespace WindowsServer
{
    /// <summary>
    /// Summary description for HandlerForMyFE
    /// </summary>
    public class Handler : IHttpHandler, System.Web.SessionState.IRequiresSessionState
    {

        private HttpContext _context;
        private HttpContext Context
        {
            get
            {
                return _context;
            }
            set
            {
                _context = value;
            }
        }

        public void ProcessRequest(HttpContext context)
        {
            Context = context;
            string filePath = context.Request.QueryString["Downloadpath"];
            filePath = context.Server.MapPath(filePath);

            if (filePath == null)
            {
                return;
            }

            System.IO.StreamReader streamReader = new System.IO.StreamReader(filePath);
            System.IO.BinaryReader br = new System.IO.BinaryReader(streamReader.BaseStream);

            byte[] bytes = new byte[streamReader.BaseStream.Length];

            br.Read(bytes, 0, (int)streamReader.BaseStream.Length);

            if (bytes == null)
            {
                return;
            }

            streamReader.Close();
            br.Close();
            string fileName = System.IO.Path.GetFileName(filePath);
            string MimeType = GetMimeType(fileName);
            string extension = System.IO.Path.GetExtension(filePath);
            char[] extension_ar = extension.ToCharArray();
            string extension_Without_dot = string.Empty;
            for (int i = 1; i < extension_ar.Length; i++)
            {
                extension_Without_dot += extension_ar[i];
            }

            string filesize = string.Empty;
            FileInfo f = new FileInfo(filePath);
            filesize = f.Length.ToString();

            //DownloadFile.DownloadFileMethod_2(Context, filePath, 5242880);
              WriteFile(bytes, fileName, filesize, MimeType + " " + extension_Without_dot, context.Response);
        }

       private void WriteFile(byte[] content, string fileName, string filesize, string contentType, HttpResponse response)
    {
        response.Buffer = true;
        response.Clear();

        response.ContentType = contentType;

        response.AddHeader("content-disposition", "attachment; filename=" + fileName);

        response.AddHeader("Content-Length", filesize);

        response.BinaryWrite(content);
        response.Flush();
        response.End();
    }

        private string GetMimeType(string fileName)
        {
            string mimeType = "application/unknown";
            string ext = System.IO.Path.GetExtension(fileName).ToLower();
            Microsoft.Win32.RegistryKey regKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext);
            if (regKey != null && regKey.GetValue("Content Type") != null)
                mimeType = regKey.GetValue("Content Type").ToString();
            return mimeType;
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

提前致谢

最佳答案

.NET中的任何数组都不能容纳超过2 ^ 31个元素（System.Int32.MaxValue）或a max size of 2 GB，这大约可以构成2 GB的字节数组。

有关解决方法，请参见http://blogs.msdn.com/b/joshwil/archive/2005/08/10/450202.aspx

另一个选择是在这些文件上使用MemoryMappedFile和Streams-这将允许访问任何大小的文件...

要使下载代码正常工作，您可以读取一个块，发送该块，再读取下一个块，等等。或者使用Stream进行读写，而无需任何中间缓冲区...

另一种选择是使用OutputStream，它可以处理大于4 GB的文件。

编辑-根据评论：

您可以在之后替换代码

if (filePath == null)
{
return;
}

与

response.Clear();

response.ContentType = GetMimeType (System.IO.Path.GetFileName(filePath));

response.AddHeader("content-disposition", "attachment; filename=" + System.IO.Path.GetFileName(filePath));

response.TransmitFile (filePath);

或

long FileL = (new FileInfo(filePath)).Length;
byte[] bytes = new byte[1024*1024];

response.Clear();

response.ContentType = GetMimeType (System.IO.Path.GetFileName(filePath));

response.AddHeader("content-disposition", "attachment; filename=" + System.IO.Path.GetFileName(filePath));

response.AddHeader("Content-Length", FileL.ToString());

using (FileStream FS = File.OpenRead(filePath))
{
int bytesRead = 0;
while ((bytesRead = FS.Read (bytes, 0, bytes.Length)) > 0 )
{
response.OutputStream.Write(bytes, 0, bytesRead);
response.Flush();
};

response.Close();
}

关于c# - 算术运算导致溢出错误-对于C#中的byte []数组，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/8070949/