C#实现文件下载的几种方式

来源:转载

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(); }}

分享给朋友:
您可能感兴趣的文章:
随机阅读: