downloadpostattachment.cs

本系统是在asp版《在线文件管理器》的基础上设计制作

//------------------------------------------------------------------------------
// <copyright company="Telligent Systems">
//     Copyright (c) Telligent Systems Corporation.  All rights reserved.
// </copyright> 
//------------------------------------------------------------------------------

using System.Web;
using System.Web.UI;

using CommunityServer.Components;
using CommunityServer.Discussions.Components;

namespace CommunityServer.Discussions.Controls 
{
	/// <summary>
	/// Summary description for PostAttachment.
	/// </summary>
	public class DownloadPostAttachment : Control 
	{
		CSContext csContext = CSContext.Current;

		protected override void Render(HtmlTextWriter writer) 
		{
			
			// Get the forum the attachment is in
			//
			Forum forum = Forums.GetForumByPostID(csContext.PostID, Users.GetUser().UserID, false);

			if (forum == null) 
			{
				throw new CSException(CSExceptionType.SectionNotFound, csContext.ForumID.ToString());
			}

			// Get the ForumPermission
			//
			ForumPermission permission = forum.ResolvePermission( Users.GetUser() ) as ForumPermission;

			// if user is not allowed to read this post, return
			//
			if (!permission.Read ) 
			{
				throw new CSException(CSExceptionType.GeneralAccessDenied, csContext.ForumID.ToString());
			}

			CommunityServer.Components.PostAttachment attachment = Posts.GetAttachment(csContext.PostID);
	
			// Todo: make the context display in browser for browser-friendly items (images, videos, etc)
			//
			System.Web.HttpContext.Current.Response.Clear();	
			System.Web.HttpContext.Current.Response.ContentType = attachment.ContentType;
	
			if (!ValidateContentTypesDisplayInBrowser(attachment.ContentType))
				System.Web.HttpContext.Current.Response.AppendHeader("content-disposition", "attachment; filename=\"" + HttpUtility.UrlPathEncode(attachment.FileName) + "\"");	
			
			if(attachment.RealFileName != "")
			{
				string realFileName = CommunityServer.Components.PostAttachment.GetAttachmentPath(attachment.UserID, attachment.RealFileName);
				
				// 以下代码为附件多线程/断点续传下载支持，由bestcomy完成，宝玉 修改了其中的bug
				#region 2005-1-11,modified by bestcomy from http://www.cnblogs.com/bestcomy
				System.Web.HttpResponse Response = System.Web.HttpContext.Current.Response;
				System.Web.HttpRequest Request = System.Web.HttpContext.Current.Request;

				System.IO.FileStream iStream = new System.IO.FileStream(realFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read,System.IO.FileShare.Read);

				// Buffer to read 10K bytes in chunk:
				byte[] buffer = new byte[10240];

				// Length of the file:
				int length;

				// Total bytes to read:
				long dataToRead = iStream.Length;

				long p = 0;
				if(Request.Headers["Range"]!=null)
				{
					Response.StatusCode = 206;
					string range = Request.Headers["Range"];
					range = range.Replace("bytes=","");
					range = range.Substring(0, range.IndexOf("-"));
					p = long.Parse( range );
				}
				if(p != 0)
				{
					Response.AddHeader("Content-Range","bytes " + p.ToString() + "-" + ((long)(dataToRead - 1)).ToString() + "/" + dataToRead.ToString());                    
				}
				Response.AddHeader("Content-Length",((long)(dataToRead-p)).ToString());

				iStream.Position = p;
				dataToRead = dataToRead - p;
				// 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, 10240);

						// Write the data to the current output stream.
						Response.OutputStream.Write(buffer, 0, length);

						// Flush the data to the HTML output.
						Response.Flush();

						buffer= new byte[10240];
						dataToRead = dataToRead - length;
					}
					else
					{
						//prevent infinite loop if user disconnects
						dataToRead = -1;
					}
				}

				iStream.Close();
				#endregion

			}
			else
			{
				System.Web.HttpContext.Current.Response.OutputStream.Write(attachment.Content, 0, attachment.Length);
			}
			System.Web.HttpContext.Current.Response.End();
		}

		/// <summary>
		/// 检查是否直接浏览器打开（不弹出保存对话框）
		/// </summary>
		/// <param name="rawContentType"></param>
		/// <returns></returns>
		bool ValidateContentTypesDisplayInBrowser(string rawContentType) 	
		{
			string[] ContentTypes = SiteSettingsManager.GetSiteSettings().ContentTypesDisplayInBrowser.Split(';');
			string[] rawTypes = rawContentType.ToLower().Split('/');

			foreach (string contentType in ContentTypes) 
			{
				string[] types = contentType.ToLower().Split('/');
				if (types.Length != 2)
					continue;
				if ((types[0] == rawTypes[0]) && (types[1] == "*" || types[1] == rawTypes[1])) 
				{
					return true;
				}
			}

			return false;
		}
	}
}