c# - 大文件上传时的 ASP.NET C# OutofMemoryException

Question

我有以下文件上传处理程序:

public class FileUploader : IHttpHandler
{
 public void ProcessRequest(HttpContext context)
 {
    HttpRequest request = context.Request;

    context.Response.ContentType = "text/html";
    context.Response.ContentEncoding = System.Text.Encoding.UTF8;
    context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
    var tempPath = request.PhysicalApplicationPath + "\\Files\\TempFiles\\";        
    byte[] buffer = new byte[request.ContentLength];
    using (BinaryReader br = new BinaryReader(request.InputStream))
    {
        br.Read(buffer, 0, buffer.Length);
    }
    var tempName = WriteTempFile(buffer, tempPath);
    context.Response.Write("{\"success\":true}");
    context.Response.End();
 }

 public bool IsReusable
 {
    get { return true; }
 }

 private string WriteTempFile(byte[] buffer, string tempPath)
 {
    var fileName = GetUniqueFileName(tempPath);
    File.WriteAllBytes(tempPath + fileName, buffer);
    return fileName;
 }
 private string GetUniqueFileName(string tempPath)
 {
    var guid = Guid.NewGuid().ToString().ToUpper();
    while (File.Exists(tempPath + guid))
    {
        guid = Guid.NewGuid().ToString().ToUpper();
    }
    return guid;
 }
}

当我上传大文件时，这会导致 OutOfMemoryException。有人能告诉我使用这样的处理程序上传大文件的正确方法是什么吗？

Answer 1

无需将文件加载到内存中即可将其写入某处。您应该使用一个小 缓冲区(可能是 8k)，并在流上循环。或者，对于 4.0，CopyTo 方法。例如:

using(var newFile = File.Create(tempPath)) {
    request.InputStream.CopyTo(newFile);
}

(它为您执行小缓冲区/循环，默认使用 4k 缓冲区，或允许通过重载传递自定义缓冲区大小)