C#保存文件
如下：
比如说我本地F盘有个文件test.txt 文件， 那么我想点击按钮 首先判断这个文件是否存在，如果不存在就弹出框，提示该文件已经不存在，如果存在就弹出框，提示下载， 就像csdn里下载一样，如图


[解决办法]
下载方法执行

C# code

public   void   Save() { if   (System.IO.File.Exists(fileName)) { FileInfo   DownloadFile   =   new   FileInfo(fileName);   System.Web.HttpContext.Current.Response.Clear(); System.Web.HttpContext.Current.Response.ClearHeaders(); System.Web.HttpContext.Current.Response.Buffer=false; System.Web.HttpContext.Current.Response.Charset   =   "GB2312 "; System.Web.HttpContext.Current.Response.ContentEncoding=System.Text.Encoding.UTF8; System.Web.HttpContext.Current.Response.ContentType= "application/octet-stream "; System.Web.HttpContext.Current.Response.AppendHeader( "Content-Disposition ", "attachment;filename= "   +System.Web.HttpUtility.UrlEncode(DownloadFile.FullName,System.Text.Encoding.UTF8)); System.Web.HttpContext.Current.Response.AppendHeader( "Content-Length ",DownloadFile.Length.ToString()); // System.Web.HttpContext.Current.Response.WriteFile(DownloadFile.FullName); // System.Web.HttpContext.Current.Response.Flush(); // System.Web.HttpContext.Current.Response.End();//原来的程序 byte[]   tmpbyte=new   byte[1024*8]; System.IO.FileStream   fs=DownloadFile.OpenRead(); int   count; while((count=fs.Read(tmpbyte,0,tmpbyte.Length))> 0) { System.Web.HttpContext.Current.Response.BinaryWrite(tmpbyte); System.Web.HttpContext.Current.Response.Flush(); } fs.Close(); System.Web.HttpContext.Current.Response.End(); } }
[解决办法]
xxx = Server.MapPath("~/xxx.txt");
if(File.Exists(xxx))
{
Response.Clear();
Response.ContentType= "application/octet-stream";  
Response.AppendHeader("Content-Disposition", "attachment;filename="+ Path.GetFileName(xxx));
Response.WriteFile(xxx);
Response.End();
}
else
{
  Response.Write("文件不存在");
}

另外，文件必须放在网站目录下，而不是放在网站目录外面
[解决办法]
C# code
protected void Page_Load(object sender, EventArgs e)    {        FileDown("D:/MyPassWord.pmb");    }    private void FileDown(string strPath)    {        System.IO.FileInfo file = new System.IO.FileInfo(strPath);        if (file.Exists)        {            Response.Clear();            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(file.FullName, System.Text.Encoding.UTF8));            Response.AddHeader("Content-Length", file.Length.ToString());            Response.ContentType = "application/octet-stream";            Response.Filter.Close();            Response.WriteFile(file.FullName);            Response.End();        }        else        {            ClientScript.RegisterStartupScript(GetType(), "", "<script language='javascript'>alert('文件不存在!');</script>");        }    }