以前做asp.net下载功能的时候都是采用:
<a
href="http://www.wang0214.com/wgcms">下载</a>
的方式来实现下载。
但后来发现，这种方法存在诸多弊端。至于弊端原因百度一下就明白了。
所以，下面分享下自己修改完善后，asp.net加密文件下载功能：
不想看详细介绍的直接点击这里下载：
开始下载：点击下载
解压密码：www.wang0214.com
1、首先新建一个用于进行下载处理的page页，如download.aspx，里面不需要写任何东西。
2、新建一个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。
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;
using System.Diagnostics;
using
System.IO;
/// <summary>
///DownloadHandler
的摘要说明
///万广互联（www.wang0214.com）
///专业品牌网站建设
///
</summary>
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; }
}
}
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：
using
System;
using System.Collections.Generic;
using System.Web;
///
<summary>
///FileHelper 的摘要说明
/// </summary>
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);
}
}
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>
5、现在新建一个aspx页面，对文件进行下载：
Default.aspx代码如下：
Default.aspx Code
<%@
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 id="Head1"
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：
Default.aspx.cs Code
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;
using System.Diagnostics;
public partial
class _Default : System.Web.UI.Page
{
//全局变量
private static object
_SyncLockObject = new object();
protected void
Page_Load(object sender, EventArgs e)
{
string url =
FileHelper.Encrypt("万广互联_深圳网站建设.jpg");
link.NavigateUrl = "~/download.aspx?fn=" + url;
}
}
通过以上详解讲解后，还不能领会的把，就下载下面的源代码吧：
开始下载：点击下载
解压密码：www.wang0214.com