ASP.NET利用HttpHandler实现多扩展名文件下载
转载自:http://www.cnblogs.com/liping13599168/archive/2009/02/08/1386111.html
1. 首先新建一个用于进行下载处理的page页，如download.aspx，里面什么东西也没有。
2. 添加一个DownloadHandler类，它继承于IHttpHandler接口，可以用来自定义HTTP 处理程序同步处理HTTP的请求。
public
class
DownloadHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
HttpResponse Response = context.Response;
HttpRequest Request = context.Request;
System.IO.Stream iStream = null ;
byte [] buffer = new Byte[ 10240 ];
int length;
long dataToRead;
try
{
string filename = FileHelper.Decrypt(Request[ " fn " ]); // 通过解密得到文件名
string filepath = HttpContext.Current.Server.MapPath( " ~/ " ) + " files/ " + filename; // 待下载的文件路径
iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
System.IO.FileAccess.Read, System.IO.FileShare.Read);
Response.Clear();
dataToRead = iStream.Length;
long p = 0 ;
if (Request.Headers[ " Range " ] != null )
{
Response.StatusCode = 206 ;
p = long .Parse(Request.Headers[ " Range " ].Replace( " bytes= " , "" ).Replace( " - " , "" ));
}
if (p != 0 )
{
Response.AddHeader( " Content-Range " , " bytes " + p.ToString() + " - " + (( long )(dataToRead - 1 )).ToString() + " / " + dataToRead.ToString());
}
Response.AddHeader( " Content-Length " , (( long )(dataToRead - p)).ToString());
Response.ContentType = " application/octet-stream " ;
Response.AddHeader( " Content-Disposition " , " attachment; filename= " + System.Web.HttpUtility.UrlEncode(System.Text.Encoding.GetEncoding( 65001 ).GetBytes(Path.GetFileName(filename))));
iStream.Position = p;
dataToRead = dataToRead - p;
while (dataToRead > 0 )
{
if (Response.IsClientConnected)
{
length = iStream.Read(buffer, 0 , 10240 );
Response.OutputStream.Write(buffer, 0 , length);
Response.Flush();
buffer = new Byte[ 10240 ];
dataToRead = dataToRead - length;
}
else
{
dataToRead = - 1 ;
}
}
}
catch (Exception ex)
{
Response.Write( " Error : " + ex.Message);
}
finally
{
if (iStream != null )
{
iStream.Close();
}
Response.End();
}
}
public bool IsReusable
{
get { return true ; }
}
}
{
public void ProcessRequest(HttpContext context)
{
HttpResponse Response = context.Response;
HttpRequest Request = context.Request;
System.IO.Stream iStream = null ;
byte [] buffer = new Byte[ 10240 ];
int length;
long dataToRead;
try
{
string filename = FileHelper.Decrypt(Request[ " fn " ]); // 通过解密得到文件名
string filepath = HttpContext.Current.Server.MapPath( " ~/ " ) + " files/ " + filename; // 待下载的文件路径
iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
System.IO.FileAccess.Read, System.IO.FileShare.Read);
Response.Clear();
dataToRead = iStream.Length;
long p = 0 ;
if (Request.Headers[ " Range " ] != null )
{
Response.StatusCode = 206 ;
p = long .Parse(Request.Headers[ " Range " ].Replace( " bytes= " , "" ).Replace( " - " , "" ));
}
if (p != 0 )
{
Response.AddHeader( " Content-Range " , " bytes " + p.ToString() + " - " + (( long )(dataToRead - 1 )).ToString() + " / " + dataToRead.ToString());
}
Response.AddHeader( " Content-Length " , (( long )(dataToRead - p)).ToString());
Response.ContentType = " application/octet-stream " ;
Response.AddHeader( " Content-Disposition " , " attachment; filename= " + System.Web.HttpUtility.UrlEncode(System.Text.Encoding.GetEncoding( 65001 ).GetBytes(Path.GetFileName(filename))));
iStream.Position = p;
dataToRead = dataToRead - p;
while (dataToRead > 0 )
{
if (Response.IsClientConnected)
{
length = iStream.Read(buffer, 0 , 10240 );
Response.OutputStream.Write(buffer, 0 , length);
Response.Flush();
buffer = new Byte[ 10240 ];
dataToRead = dataToRead - length;
}
else
{
dataToRead = - 1 ;
}
}
}
catch (Exception ex)
{
Response.Write( " Error : " + ex.Message);
}
finally
{
if (iStream != null )
{
iStream.Close();
}
Response.End();
}
}
public bool IsReusable
{
get { return true ; }
}
}
3. 这里涉及到一个文件名加解密的问题，是为了防止文件具体名称暴露在状态栏中，所以添加一个FileHelper类，代码如下：
public
class
FileHelper
{
public static string Encrypt( string filename)
{
byte [] buffer = HttpContext.Current.Request.ContentEncoding.GetBytes(filename);
return HttpUtility.UrlEncode(Convert.ToBase64String(buffer));
}
public static string Decrypt( string encryptfilename)
{
byte [] buffer = Convert.FromBase64String(encryptfilename);
return HttpContext.Current.Request.ContentEncoding.GetString(buffer);
}
}
{
public static string Encrypt( string filename)
{
byte [] buffer = HttpContext.Current.Request.ContentEncoding.GetBytes(filename);
return HttpUtility.UrlEncode(Convert.ToBase64String(buffer));
}
public static string Decrypt( string encryptfilename)
{
byte [] buffer = Convert.FromBase64String(encryptfilename);
return HttpContext.Current.Request.ContentEncoding.GetString(buffer);
}
}
利用Base64码对文件名进行加解密处理。
4. 在Web.config上，添加httpHandlers结点，如下：
<
system.web
>
< httpHandlers >
< add verb ="*" path ="download.aspx" type ="DownloadHandler" />
</ httpHandlers >
</ system.web >
< httpHandlers >
< add verb ="*" path ="download.aspx" type ="DownloadHandler" />
</ httpHandlers >
</ system.web >
5. 现在新建一个aspx页面，对文件进行下载：
Default.aspx代码如下：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>文件下载</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:HyperLink ID="link" runat="server" Text="文件下载"></asp:HyperLink>
</div>
</form>
</body>
</html>
Default.aspx.cs代码如下：
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string url = FileHelper.Encrypt("DesignPattern.chm");
link.NavigateUrl = "~/download.aspx?fn=" + url;
}
}