xaml采用linkbutton 其navigateuri属性链接到服务端下载的ashx文档 如 hyperlinkbutton margin=32,135,198,140 content=hyperlinkbutton navigateuri=http://localhost:1399/download.ashx / download.ashx 如下 code 1 imports system.web 2 imports
xaml采用linkbutton 其navigateuri属性链接到服务端下载的ashx文档
如
download.ashx如下
code
1imports system.web
2imports system.web.services
3imports system.net
4public class downloadclass download
5 implements system.web.ihttphandler
6
7 private chunksize as long = 102400 '100k 每次读取文件，只读取100ｋ，这样可以缓解服务器的压力
8
9 sub processrequest()sub processrequest(byval context as httpcontext) implements ihttphandler.processrequest
10 dim filename as string = aaa.jpg '客户端保存的文件名
11 dim filepath as string = context.server.mappath(image/img_1370.jpg) '路径
12
13 dim fileinfo as system.io.fileinfo = new system.io.fileinfo(filepath)
14
15 if fileinfo.exists = true then
16
17 dim buffer(chunksize) as byte
18
19 context.response.clear()
20 dim istream as system.io.filestream = system.io.file.openread(filepath)
21 dim datalengthtoread as long = istream.length '获取下载的文件总大小
22
23 context.response.contenttype = application/octet-stream
24 '通知浏览器下载文件而不是打开
25 context.response.addheader(content-disposition, attachment; filename= & _
26 httputility.urlencode(filename, system.text.encoding.utf8))
27loop1:
28 while datalengthtoread > 0 and context.response.isclientconnected
29 dim lengthread as integer = istream.read(buffer, 0, convert.toint32(chunksize)) '读取的大小
30 context.response.outputstream.write(buffer, 0, lengthread)
31 context.response.flush()
32 datalengthtoread = datalengthtoread - lengthread
33 end while
34
35 context.response.close()
36 context.response.end()
37 end if
38
39 'context.response.contenttype = text/plain
40 'context.response.write(hello world!)
41
42 end sub
43
44 readonly property isreusable()property isreusable() as boolean implements ihttphandler.isreusable
45 get
46 return false
47 end get
48 end property
49
50end class