//指定下載的檔名
string fileName = "網頁原始碼.txt";//客戶端儲存的檔名
//指定下載的url地址：http://www.baidu.com
string url = "http://www.baidu.com";
WebClient client = new WebClient();用於傳遞url資源的方法
client.Encoding = Encoding.UTF8;
byte[] html = client.DownloadData(url);
string strPath = MapPath("~/html");定義儲存路徑
if(!Directory.Exists
 
(strPath))
{
    Directory.CreateDirectory(strPath);
}
string savePath = Path.Combine(strPath,"html.txt");//下載檔案的詳細地址
using(FileStream fsSave = new FileStream(savePath, FileMode.Create, FileAccess.Write, FileShare.ReadWrite))
{
    fsSave .Write(html, 0, html.Length);
}
//義字元流的形式下載檔案
 FileStream fs = new FileStream(savePath, FileMode.Open
 
);
            byte[] bytes = new byte[(int)fs.Length];
            fs.Read(bytes, 0, bytes.Length);
            fs.Close();
            Response.ContentType = "application/octet-stream";
//通知瀏覽器下載檔案而不是開啟
            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode
 
(fileName, System.Text.Encoding.UTF8));
            Response.BinaryWrite(bytes);
            Response.Flush();
            Response.End();