c#文件下载示例的4种方法分享

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)
{
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)
{
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();
}
}