服务器下载文件

#region 从服务器下载

        //一、TransmitFile实现下载 
        protected void Button3_Click(object sender, EventArgs e)
        {
            /* 
            微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite 
            下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 
            代码如下： 
            */
            Response.ContentType = "application/x-zip-compressed";
            Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");
            string filename = Server.MapPath("DownLoad/z.zip");
            Response.TransmitFile(filename);
        }

        //二、WriteFile实现下载 
        protected void Button4_Click(object sender, EventArgs e)
        {
            /* 
            using System.IO;

            */
            string fileName = "asd.txt";//客户端保存的文件名 
            string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

            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();
        }

        //三、WriteFile分块下载 
        protected void Button5_Click(object sender, EventArgs e)
        {
            string fileName = "aaa.txt";//客户端保存的文件名 
            string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

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

            if (fileInfo.Exists == true)
            {
                const long ChunkSize = 102400;//100K 每次读取文件，只读取100K，这样可以缓解服务器的压力 
                byte[] buffer = new byte[ChunkSize];

                Response.Clear();
                System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
                long dataLengthToRead = iStream.Length;//获取下载的文件总大小 
                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));//读取的大小 
                    Response.OutputStream.Write(buffer, 0, lengthRead);
                    Response.Flush();
                    dataLengthToRead = dataLengthToRead - lengthRead;
                }
                Response.Close();
            }
        }

        //四、流方式下载 
        protected void Button6_Click(object sender, EventArgs e)
        {
            string fileName = "aaa.txt";//客户端保存的文件名 
            string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

            //以字符流的形式下载文件 
            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";
            //通知浏览器下载文件而不是打开 
            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");
            //'文件名称
            WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) + "'");
            WebForm.Response.ContentType = "Application/octet-stream";
            //'文件内容
            WebForm.Response.Write(FileBody);//-----------
            WebForm.Response.End();
        }


        //上面这段代码是下载一个动态产生的文本文件，若这个文件已经存在于服务器端的实体路径，则可以通过下面的函数：
        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");
            //文件名称
            WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) + "'");
            WebForm.Response.ContentType = "Application/octet-stream";
            //文件内容
            WebForm.Response.Write(System.IO.File.ReadAllBytes(FilePath));//---------
            WebForm.Response.End();
        }

        #endregion