asp.net文件上传下载的简单实现

protected void btnUpload_Click(object sender, EventArgs e)
{
if (FileUpload1.HasFile)
{
/*通过文件扩展名判断文件类型*/
string fileExt = System.IO.Path.GetExtension(FileUpload1.FileName);
if (fileExt != ".doc" && fileExt != ".docx" && fileExt != ".wps")
{
lblMsg.Text = "文件类型错误！应为：doc、docx或wps";
return;
}
/*限制文件大小*/
if (FileUpload1.PostedFile.ContentLength > 100 * 1024)
{
lblMsg.Text = "文件应小于100KB";
return;
}
FileUpload1.SaveAs(Server.MapPath("虚拟路径") + FileUpload1.FileName);
lblMsg.Text = "文件上传成功！";
}
else
{
lblMsg.Text = "未选择上传文件";
}
}

protected void btnDownload_Click(object sender, EventArgs e)
{
string fileName = "文件名.扩展名";
FileInfo fileInfo = new FileInfo(Server.MapPath("虚拟路径") + fileName);
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment;FileName=" + HttpUtility.UrlEncode(fileName));
/*这里注意，如果没有下面一句，很可能会造成“文件已损坏”等情况*/
Response.AddHeader("Content-Length", fileInfo.Length.ToString());
Response.WriteFile(Server.MapPath("虚拟路径") + fileName);
}