上传超大文件的httpModule

最新推荐文章于 2016-10-15 23:37:24 发布

原创最新推荐文章于 2016-10-15 23:37:24 发布 · 2k 阅读

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#httpmodule #application #buffer #byte #encoding #null

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本文介绍了一个自定义的HTTP上传模块，用于处理文件上传过程中的预读取和分块读取功能，确保上传过程的平滑进行，并提供了配置示例。

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Globalization;
using System.IO;
using System.Text;
using System.Web;
using System.Reflection;

namespace myHttpModule
{
/// <summary>
/// HttpUploadModule 的摘要说明。
/// </summary>
public class HttpUploadModule: IHttpModule
{
  public HttpUploadModule()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }
  public void Init(HttpApplication application)
  {
   application.BeginRequest += new EventHandler(this.Application_BeginRequest);
   application.EndRequest += new EventHandler(this.Application_EndRequest);
   application.Error += new EventHandler(this.Application_Error);
  }

  public void Dispose()
  {
  }

  private void Application_BeginRequest(Object sender, EventArgs e)
  {
   HttpApplication app = sender as HttpApplication;

   // 如果是文件上传
   if (IsUploadRequest(app.Request))
   {
    // 返回 HTTP 请求正文已被读取的部分。
    HttpWorkerRequest request = GetWorkerRequest(app.Context);
    Encoding encoding = app.Context.Request.ContentEncoding;

    int bytesRead = 0; // 已读数据大小
    int read; // 当前读取的块的大小
    int count = 8192; // 分块大小
    byte[] buffer; // 保存所有上传的数据
    byte[] tempBuff = null;

    if (request != null)
    {
     tempBuff = request.GetPreloadedEntityBody();
    }
    if (tempBuff != null)
    {
     // 获取上传大小
     //
     long length = long.Parse(request.GetKnownRequestHeader(HttpWorkerRequest.HeaderContentLength));

     buffer = new byte[length];
     count = tempBuff.Length; // 分块大小

     // 将已上传数据复制过去
     //
     Buffer.BlockCopy(tempBuff, 0, buffer, bytesRead, count);

     // 开始记录已上传大小
     //
     bytesRead = tempBuff.Length;

     // 循环分块读取，直到所有数据读取结束
     //
     while (request.IsClientConnected() &&
      !request.IsEntireEntityBodyIsPreloaded() &&
      bytesRead < length
      )
     {
      // 如果最后一块大小小于分块大小，则重新分块
      //
      if (bytesRead + count > length)
      {
       count = (int)(length - bytesRead);
       tempBuff = new byte[count];
      }

      // 分块读取
      //
      read = request.ReadEntityBody(tempBuff, count);

      // 复制已读数据块
      //
      Buffer.BlockCopy(tempBuff, 0, buffer, bytesRead, read);

      // 记录已上传大小
      //
      bytesRead += read;

     }
     if (
      request.IsClientConnected() &&
      !request.IsEntireEntityBodyIsPreloaded()
      )
     {

      // 传入已上传完的数据
      //
      InjectTextParts(request, buffer);

// 表示上传已结束

     }
    }
   }
  }

  /// <summary>
  /// 结束请求后移除进度信息
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void Application_EndRequest(Object sender, EventArgs e)
  {

}

  /// <summary>
  /// 如果出错了设置进度信息中状态为“Error”
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void Application_Error(Object sender, EventArgs e)
  {

}

HttpWorkerRequest GetWorkerRequest(HttpContext context)
{

   IServiceProvider provider = (IServiceProvider)HttpContext.Current;
   return (HttpWorkerRequest)provider.GetService(typeof(HttpWorkerRequest));
  }

  /// <summary>
  /// 传入已上传完的数据
  /// </summary>
  /// <param name="request"></param>
  /// <param name="textParts"></param>
  void InjectTextParts(HttpWorkerRequest request, byte[] textParts)
  {
   BindingFlags bindingFlags = BindingFlags.Instance | BindingFlags.NonPublic;

   Type type = request.GetType();

   while ((type != null) && (type.FullName != "System.Web.Hosting.ISAPIWorkerRequest"))
   {
    type = type.BaseType;
   }

   if (type != null)
   {
    type.GetField("_contentAvailLength", bindingFlags).SetValue(request, textParts.Length);
    type.GetField("_contentTotalLength", bindingFlags).SetValue(request, textParts.Length);
    type.GetField("_preloadedContent", bindingFlags).SetValue(request, textParts);
    type.GetField("_preloadedContentRead", bindingFlags).SetValue(request, true);
   }
  }

  /// <summary>
  /// 是否为附件上传
  /// 判断的根据是ContentType中有无multipart/form-data
  /// </summary>
  /// <param name="request"></param>
  /// <returns></returns>
  bool IsUploadRequest(HttpRequest request)
  {
   return request.ContentType.ToLower()=="multipart/form-data";
  }

}
}

需要在web.config中加入

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