第一种下载方式：

Label Label5 = GridView1.Rows[e.RowIndex].Cells[0].Controls[0].FindControl("Label5") as Label;                Response.ContentType = "application/x-zip-compressed";                Response.AddHeader("Content-Disposition", "attachment;filename=" + Label5.Text.Trim() + "");                string filename = Server.MapPath("gxxz/upload/" + Label5.Text.Trim());                Response.TransmitFile(filename);

第二种下载方式：

Label Label5 = GridView1.Rows[e.RowIndex].Cells[0].Controls[0].FindControl("Label5") as Label;    		string fileName = Label5.Text.Trim();//客户端保存的文件名    		string filePath = Server.MapPath("gxxz/upload/" + Label5.Text.Trim());//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();

第三种下载方式：

Label Label5 = GridView1.Rows[e.RowIndex].Cells[0].Controls[0].FindControl("Label5") as Label;            	string fileName = Label5.Text.Trim();//客户端保存的文件名            	string filePath = Server.MapPath("gxxz/upload/" + Label5.Text.Trim());//路径            	FileInfo info = new FileInfo(filePath);            	long fileSize = info.Length;            	Response.Clear();            	Response.ContentType = "application/x-zip-compressed";            	Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);            	//不指明Content-Length用Flush的话不会显示下载进度             	Response.AddHeader("Content-Length", fileSize.ToString());            	Response.TransmitFile(filePath, 0, fileSize);            	Response.Flush();            	Response.Close();

第四种下载方式：

string fileName = "CodeShark.zip";//客户端保存的文件名    		string filePath = Server.MapPath("DownLoad/CodeShark.zip");//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();        	}