fileupload控件上传、文件下载

常遇到上传下载的功能，这里把我习惯的用法写下来：

上传：

string fileName = "";
fileName = this.fu_pic.FileName;
if (string.IsNullOrEmpty(fileName))
　　isPic = "0";
else
　　isPic = "1";

//附件不为空的时候上传图片，否则不处理
if (isPic == "1")
{
　　byte[] arrayByte = this.fu_pic.FileBytes;
　　if (arrayByte.Length <= 0)
　　{
　　　　//Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('上传图片是空文件！')</script>");
　　　　AlertMessage("上传图片是空文件！");
　　　　this.fu_pic.Focus();
　　　　return;
　　}

　　string extention = fileName.Substring(fileName.LastIndexOf(".") + 1);
　　if (extention.ToUpper() != "JPG"
                    && extention.ToUpper() != "BMP"
                    && extention.ToUpper() != "PNG"
                    && extention.ToUpper() != "GIF")
　　{
　　　　//Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('图片格式错误，请上传jpg/bmp/png/gif格式图片！')</script>");
　　　　AlertMessage(@"图片格式错误，请上传jpg/bmp/png/gif格式图片！");
　　　　this.fu_pic.Focus();
　　　　return;
　　}
　　else
　　{
　　　　//按照年/月 生成文件目录
　　　　fileName = string.Format(@"UploadImage{0}{3}{1}{2}", DateTime.Now.Year.ToString(), DateTime.Now.ToString("yyyyMMddHHmmssfff"), fileName, DateTime.Now.Month.ToString());
　　　　//获取附件上传物理路径（这里设置在config文件中）
　　　　string dePath = ConfigurationManager.AppSettings["upload"].ToString();
　　　　string filePath = Path.Combine(dePath, fileName);//Server.MapPath(@".." + fileName);//外面一层就是网站目录
　　　　if (saveView(arrayByte, filePath))
　　　　{
　　　　　　//saveAttach = true;

　　　　}
　　　　else
　　　　{
　　　　　　//saveAttach = false;
　　　　　　//Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('图片上传服务器失败！')</script>");
　　　　　　AlertMessage("图片上传服务器失败！");
　　　　　　this.fu_pic.Focus();
　　　　　　return;
　　　　}
　　}
}

public bool saveView(byte[] arry_byte, string filePath)
    {
        bool rst = false;
        FileStream saveStream = null;
        try
        {
            //判断文件夹是否存在
            FileInfo file = new FileInfo(filePath);
            if (!file.Exists)
            {
                if (!Directory.Exists(file.DirectoryName))
                    Directory.CreateDirectory(file.DirectoryName);
            }
            file = null;

            //保存文件
            saveStream = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            saveStream.Write(arry_byte, 0, arry_byte.Length);
            saveStream.Close();
            rst = true;
        }
        catch (Exception)
        {
            rst = false;
        }

        return rst;
    }

下载保存：

/// <summary>
        /// 下载服务端文件
        /// </summary>
        /// <param name="fileName">下载时客户端显示名称</param>
        /// <param name="filePath">服务端文件完全物理路径</param>
        /// <returns></returns>
        public void DownloadFile(string fileName, string filePath)
        {
            //服务端文件是否存在
            if (File.Exists(filePath))
            {
                FileInfo fi = new FileInfo(filePath);
                long length = fi.Length;

                //读取文件到流sr中,using为防止文件被进程占据，强制释放资源
                using (FileStream sr = new FileStream(filePath, FileMode.Open))
                {
                    int startlength = 0;
                    int bufferSize = 1;
                    byte[] buffer = new byte[bufferSize];
                    byte[] allBuffer = new byte[length];

                    //循环读取流到allBuffer中
                    while (startlength < length)
                    {
                        //读取bytes个字节到buff中的0到bufferSize位置
                        //sr.read后，sr自动移动到读取的位置
                        int bytes = sr.Read(buffer, 0, bufferSize);

                        //将buff内容存入allBuffer中
                        allBuffer[startlength] = buffer[0];

                        //前进bytes个位置
                        startlength += bytes;
                    }

                    //清空缓存中的流
                    Response.Clear();
                    Response.ClearContent();
                    Response.ClearHeaders();

                    //输出流
                    Response.AddHeader("Accept-Ranges", "bytes");
                    Response.ContentType = "application/octet-stream";
                    Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, Encoding.GetEncoding("gb2312")));
                    Response.BinaryWrite(allBuffer);
                    Response.Flush();
                    Response.End();
                }
            }
        }

更加简洁的下载：

 string fileName = "日志.txt";
            string txtFullFilePath = "c:/test/aa.txt";

            if (File.Exists(Server.MapPath(txtFullFilePath)))
            {
                //文件对象
                FileInfo fileInfo = new FileInfo(Server.MapPath(txtFullFilePath));
                Response.Clear();
                Response.ClearContent();
                Response.ClearHeaders();
                Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(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();
            }