上篇博客也说了下C#中通过XML导出Excel，这些文件操作都挺有用的，下面是文件的下载，之前做项目都是把它写的空间日志中,以后有时间了把它们都弄出来

先把有问题的代码贴出来吧

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;namespace infoPlatClient.NetDisk
{public partial class downLoad : Com.DRPENG.Common.WebStruct.BaseForm{/// <summary>/// 取得要下载文件的路径/// </summary>private string fileRpath{get{return Request["fileRpath"] == null ? "" : Request["fileRpath"];}}/// <summary>/// 取得要下载文件的名称/// </summary>protected void Page_Load(object sender, EventArgs e){if (!IsPostBack)this.DownloadFile();}public void DownloadFile(){Response.ClearHeaders();Response.Clear();Response.Expires = 0;Response.Buffer =true;Response.AddHeader("Accept-Language", "zh-tw");string name = System.IO.Path.GetFileName(fileRpath);System.IO.FileStream files = new FileStream(fileRpath, FileMode.Open, FileAccess.Read, FileShare.Read);byte[] byteFile=null;if (files.Length == 0){byteFile=new byte[1];}else{byteFile = new byte[files.Length];}files.Read(byteFile, 0, (int)byteFile.Length);files.Close();Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(name, System.Text.Encoding.UTF8));Response.ContentType = "application/octet-stream;charset=gbk";Response.BinaryWrite(byteFile);Response.End();}}
}之前一直用这种下载方式，可是有一次用户上传了一个700Mb的文件时报内存溢出的问题，分析了一下原因，用户的内存只有256M，而下载文件时要创建内存流，导致了内存溢出。解决方案:1>WriteFile分块下载，就是每次下载指定数量的多件;2>通过超链接的方式;lblDownLoad.Text = "<a href='" + drv["VPath"].ToString() + "'>下载</a>"下面是四种实现文件下载的方式:using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;public partial class _Default : System.Web.UI.Page
{protected void Page_Load(object sender, EventArgs e){}//TransmitFile实现下载protected void Button1_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);}//WriteFile实现下载protected void Button2_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();}//WriteFile分块下载protected void Button3_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();}}//流方式下载protected void Button4_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();}
}