asp.net 下载文件源代码
.net获取 网站的虚拟目录 名字

Request.ApplicationPath.TrimStart('/')

没想到就这么一句话就搞定了


增加命名空间：
using System.Net;
using System.IO;

/// <summary>
/// 下载文件
/// </summary>
/// <param name="URL">要下载文件网址</param>
public void downloadfile(string URL)
{
WebClient client=new WebClient();
int n = URL.LastIndexOf('/');
string URLAddress = URL.Substring(0,n); //取得网址
string fileName = URL.Substring(n+1,URL.Length-n-1); //取得文件名
string Dir = Server.MapPath("./"); //下载文件存放路径

string Path = Dir+'\\'+fileName; //下载文件存放完整路径

Stream stream = client.OpenRead(URL);

StreamReader reader = new StreamReader(stream);
byte[] mbyte = new byte[100000];
int allbyte = (int)mbyte.Length;
int startbyte = 0;
while(allbyte>0) //循环读取
{
int m = stream.Read(mbyte,startbyte,allbyte);
if(m==0)
break;

startbyte+=m;
allbyte-=m;
}

FileStream fstr = new FileStream(Path,FileMode.OpenOrCreate,FileAccess.Write);
fstr.Write(mbyte,0,startbyte); //写文件
stream.Close();
fstr.Close();
}