C#如何实现 文件 下载 功能？？

我在开发网站中，写了一个上传附件的功能，文件保存到目录下，路径保存到数据库中，上传现在是写完了，但是下载的时候有一些小问题。当前我写的下载功能之直接把 上传的附件对应的物理路径 作为链接添加到了“下载”链接上，这样点击“下载”有些类型的文件能自动下载，如 .rar格式的文件，但是例如.jpg、.txt、.mp3等格式的文件就不能自动下载，而是在线给打开了，这样就体现不了下载的功能了，但是如果右键点击“下载”——“目标另存为”，就能弹出来下载保存的对话框。请问如何能点击“下载”就自动实现下载或者弹出保存的那个对话框啊？？

// 设置返回内容的类型
Response.ContentType = "application/octet-stream";
// 通知浏览器，弹出对话框
Response.AddHeader( "Content-Disposition","attachment; filename=xxx.jpg")

关注中

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(); } } 这里提供4种常用下载方式 以供参考

你好，能教教我吗？上传和下载功能的实现，谢谢了，q：279480453