xaml採用LinkButton 其NavigateUri屬性連結到服務端下載的ashx文檔
如
<HyperlinkButton Margin="32,135,198,140" Content="HyperlinkButton" NavigateUri="http://localhost:1399/download.ashx" />
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 每次讀取檔案，唯讀取100Ｋ，這樣可以緩解伺服器的壓力
8
9 Sub ProcessRequest()Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
10 Dim fileName As String = "aaa.JPG" '用戶端儲存的檔案名稱
11 Dim filePath As String = context.Server.MapPath("image/IMG_1370.JPG") '路徑
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 '擷取下載的檔案總大小
22
23 context.Response.ContentType = "application/octet-stream"
24 '通知瀏覽器下載檔案而不是開啟
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)) '讀取的大小
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
