//TransmitFile實現下載 
    protected void Button1_Click(object sender, EventArgs e)
    {
        /* 
        微軟為Response對象提供了一個新的方法TransmitFile來解決使用Response.BinaryWrite 
        下載超過400mb的文件時導致Aspnet_wp.exe進程回收而無法成功下載的問題。 
        代碼如下： 
        */ 
        Response.ContentType = "application/x-zip-compressed";
        Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");
        string filename = Server.MapPath("DownLoad/z.zip");
        Response.TransmitFile(filename);
    }

    //WriteFile實現下載 
    protected void Button2_Click(object sender, EventArgs e)
    {
        /* 
        using System.IO;

        */
        string fileName = "asd.txt";//客戶端保存的文件名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

        FileInfo fileInfo = new FileInfo(filePath);
        Response.Clear();
        Response.ClearContent();
        Response.ClearHeaders();
        Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
        Response.AddHeader("Content-Length", fileInfo.Length.ToString());
        Response.AddHeader("Content-Transfer-Encoding", "binary");
        Response.ContentType = "application/octet-stream";
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
        Response.WriteFile(fileInfo.FullName);
        Response.Flush();
        Response.End();
    }

    //WriteFile分塊下載 
    protected void Button3_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客戶端保存的文件名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

        System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);

        if (fileInfo.Exists == true)
        {
            const long ChunkSize = 102400;//100K 每次讀取文件，只讀取100K，這樣可以緩解服務器的壓力 
            byte[] buffer = new byte[ChunkSize];

            Response.Clear();
            System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
            long dataLengthToRead = iStream.Length;//獲取下載的文件總大小 
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
            while (dataLengthToRead > 0 && Response.IsClientConnected)
            {
                int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//讀取的大小 
                Response.OutputStream.Write(buffer, 0, lengthRead);
                Response.Flush();
                dataLengthToRead = dataLengthToRead - lengthRead;
            }
            Response.Close();
        }
    }

    //流方式下載 
    protected void Button4_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客戶端保存的文件名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

        //以字符流的形式下載文件 
        FileStream fs = new FileStream(filePath, FileMode.Open);
        byte[] bytes = new byte[(int)fs.Length];
        fs.Read(bytes, 0, bytes.Length);
        fs.Close();
        Response.ContentType = "application/octet-stream";
        //通知瀏覽器下載文件而不是打開 
        Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }

//----------------------------------------------------------

public void DownloadFile( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FileBody )
{

　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
　　WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//'文件名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'");
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//'文件內容
　　WebForm.Response.Write(FileBody);//-----------
    WebForm.Response.End();
}

//上面這段代碼是下載一個動態產生的文本文件，若這個文件已經存在于服務器端的實體路徑，則可以通過下面的函數：

public void DownloadFileByFilePath( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FilePath )
{
　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
    WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//文件名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) +"'" );
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//文件內容
　　WebForm.Response.Write(System.IO.File.ReadAllBytes(FilePath));//---------
　　WebForm.Response.End();
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

--保存文檔 
string docName, docExtended; 
Stream doc = fuDoc.FileContent; 
int docLength = fuDoc.PostedFile.ContentLength; 
byte[] docData = new byte[docLength]; 
doc.Read(docData, 0, docLength); 
docExtended = fuDoc.FileName.Substring(fuDoc.FileName.IndexOf(".")); 
if (string.IsNullOrEmpty(tbDoc.Text)) 
docName = fuDoc.FileName; 
else 
docName = tbDoc.Text + docExtended; 
SafetyDocInfo data = new SafetyDocInfo(ddlSort.Text, docName, fuDoc.PostedFile.ContentType, docData); 
SafetyDoc safety = new SafetyDoc(); 
safety.Insert(data); 
tbDoc.Text = string.Empty; 
－－打開文檔 
public void ViewSafetyDoc(string pDocSort, string pDocName) 
{ 
OracleParameter[] parms = GetSafetyDocParm(SQL_View_SafetyDoc); 
parms[0].Value = pDocSort; 
parms[1].Value = pDocName; 
using (OracleDataReader rdr = OracleHelper.ExecuteReader(OracleHelper.ConnectionString, CommandType.Text, SQL_View_SafetyDoc, parms)) 
{ 
while (rdr.Read()) 
{ 
HttpContext.Current.Response.Clear(); 
HttpContext.Current.Response.Buffer = true; 
HttpContext.Current.Response.Charset = "GB2312"; 
HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312"); 
HttpContext.Current.Response.ContentType = rdr.GetString(1); 
HttpContext.Current.Response.BinaryWrite((byte[])rdr["Doc"]); 
string FileName = rdr.GetString(0); 
FileName = System.Web.HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8); 
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + FileName); 
} 
} 
}