C#文件下载

1，Http 协议中有专门的指令来告知浏览器, 本次响应的是一个需要下载的文件. 格式如下:
Content-Disposition: attachment;filename=filename.ext
以上指令即标记此次响应流是附件,且附件文件名为 filename.ext
注意：
(1): 中文文件名需要进行URLEncode编码, 否则在IE 6 下会提示是”无法识别的文件”.

但经实际测试,在Chrome下不进行URLEncode编码, 也能正常显示.

(2): 文件名不能有空格, 否则也会被认为是”无法识别的文件”.

(3): [ASP.Net中] 向响应流中添加该指令必须使用 response.AddHeader() 函数; 使用

response.Header.Add() 则会报错.
 

//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); i

f (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";

Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));//通知浏览器下载文件而不是打开

Response.BinaryWrite(bytes);

Response.Flush();

Response.End();

}

}