我正在尝试使用通用处理程序上传图像，如下所示，我有一个普通的aspx页面，我在上传后显示所有上传的图像。一切正常。
<%@ WebHandler Language="VB" Class="Upload"%>
Imports System
Imports System.Web
Imports System.Threading
Imports System.Web.Script.Serialization
Imports System.IO
Public Class Upload : Implements IHttpHandler, System.Web.SessionState.IRequiresSessionState
Public Class FilesStatus
Public Property thumbnail_url() As String
Public Property name() As String
Public Property url() As String
Public Property size() As Integer
Public Property type() As String
Public Property delete_url() As String
Public Property delete_type() As String
Public Property [error]() As String
Public Property progress() As String
End Class
Private ReadOnly js As New JavaScriptSerializer()
Private ingestPath As String
Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
Dim r = context.Response
ingestPath = context.Server.MapPath("~/UploadedImages/")
r.AddHeader("Pragma", "no-cache")
r.AddHeader("Cache-Control", "private, no-cache")
HandleMethod(context)
End Sub
Private Sub HandleMethod(ByVal context As HttpContext)
Select Case context.Request.HttpMethod
Case "HEAD", "GET"
ServeFile(context)
Case "POST"
UploadFile(context)
Case "DELETE"
DeleteFile(context)
Case Else
context.Response.ClearHeaders()
context.Response.StatusCode = 405
End Select
End Sub
Private Sub DeleteFile(ByVal context As HttpContext)
Dim filePath = ingestPath & context.Request("f")
If File.Exists(filePath) Then
File.Delete(filePath)
End If
End Sub
Private Sub ServeFile(ByVal context As HttpContext)
If String.IsNullOrEmpty(context.Request("f")) Then
ListCurrentFiles(context)
Else
DeliverFile(context)
End If
End Sub
Private Sub UploadFile(ByVal context As HttpContext)
Dim statuses = New List(Of FilesStatus)()
Dim headers = context.Request.Headers
If String.IsNullOrEmpty(headers("X-File-Name")) Then
UploadWholeFile(context, statuses)
Else
UploadPartialFile(headers("X-File-Name"), context, statuses)
End If
WriteJsonIframeSafe(context, statuses)
End Sub
Private Sub UploadPartialFile(ByVal fileName As String, ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
If context.Request.Files.Count <> 1 Then
Throw New HttpRequestValidationException("Attempt to upload chunked file containing more than one fragment per request")
End If
Dim inputStream = context.Request.Files(0).InputStream
Dim fullName = ingestPath & Path.GetFileName(fileName)
Using fs = New FileStream(fullName, FileMode.Append, FileAccess.Write)
Dim buffer = New Byte(1023) {}
Dim l = inputStream.Read(buffer, 0, 1024)
Do While l > 0
fs.Write(buffer, 0, l)
l = inputStream.Read(buffer, 0, 1024)
Loop
fs.Flush()
fs.Close()
End Using
statuses.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & fileName, .url = "Upload.ashx?f=" & fileName, .name = fileName, .size = CInt((New FileInfo(fullName)).Length), .type = "image/png", .delete_url = "Upload.ashx?f=" & fileName, .delete_type = "DELETE", .progress = "1.0"})
End Sub
Private Sub UploadWholeFile(ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
For i As Integer = 0 To context.Request.Files.Count - 1
Dim file = context.Request.Files(i)
file.SaveAs(ingestPath & Path.GetFileName(file.FileName))
Thread.Sleep(1000)
Dim fname = Path.GetFileName(file.FileName)
statuses.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & fname, .url = "Upload.ashx?f=" & fname, .name = fname, .size = file.ContentLength, .type = "image/png", .delete_url = "Upload.ashx?f=" & fname, .delete_type = "DELETE", .progress = "1.0"})
Next i
End Sub
Private Sub WriteJsonIframeSafe(ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
context.Response.AddHeader("Vary", "Accept")
Try
If context.Request("HTTP_ACCEPT").Contains("application/json") Then
context.Response.ContentType = "application/json"
Else
context.Response.ContentType = "text/plain"
End If
Catch
context.Response.ContentType = "text/plain"
End Try
Dim jsonObj = js.Serialize(statuses.ToArray())
context.Response.Write(jsonObj)
End Sub
Private Sub DeliverFile(ByVal context As HttpContext)
Dim filePath = ingestPath & context.Request("f")
If File.Exists(filePath) Then
context.Response.ContentType = "application/octet-stream"
context.Response.WriteFile(filePath)
context.Response.AddHeader("Content-Disposition", "attachment, filename=""" & context.Request("f") & """")
Else
context.Response.StatusCode = 404
End If
End Sub
Private Sub ListCurrentFiles(ByVal context As HttpContext)
Dim files = New List(Of FilesStatus)()
Dim names = Directory.GetFiles(context.Server.MapPath("~/UploadedImages/"), "*", SearchOption.TopDirectoryOnly)
For Each name In names
Dim f = New FileInfo(name)
files.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & f.Name, .url = "Upload.ashx?f=" & f.Name, .name = f.Name, .size = CInt(f.Length), .type = "image/png", .delete_url = "Upload.ashx?f=" & f.Name, .delete_type = "DELETE"})
Next name
context.Response.AddHeader("Content-Disposition", "inline, filename=""files.json""")
Dim jsonObj = js.Serialize(files.ToArray())
context.Response.Write(jsonObj)
context.Response.ContentType = "application/json"
End Sub
Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property
End Class
现在我想通过生成随机字符串添加会话变量，并将上传的图像添加到新创建的随机字符串中。
1.我在SO上看到这个Question使用System.Web.SessionState.IRequiresSessionState进行会话，我如何create folder使用access并将我的图片添加到该文件夹中这样做我如何在normal aspx页面中{{1}}此会话变量。
2.（或者）更好的方法是在aspx页面中创建会话变量并将其传递给处理程序？如果是这样，我该怎么做？
3.我正试图从我的处理程序中找到控件。这可能吗？如果有人知道如何得到这个，那么我的问题也会得到解决，所以我试图从m aspx页面创建一个会话。
任何人都可以解释处理这种情况的更好方法。
答案 0 :(得分：3)
我完全同意jbl的评论。
HttpContext.Current.Session获取和设置会话。Here is an example，我在HttpHandler上使用了session。但是，它是在c＃上（希望你能理解）。
答案 1 :(得分：0)
这不是一个真正的答案，但@Knvn编写了一个我无法理解的C＃示例，所以我使用转换器将其转换为VB。将它贴在这里以防将来帮助某人。
Public Class HttpHandler
Implements IHttpHandler
Implements IRequiresSessionState
Public Sub New()
End Sub
Public Sub ProcessRequest(context As HttpContext)
Dim Request As HttpRequest = context.Request
Dim Response As HttpResponse = context.Response
If SessionHandler.Current.UserID = 0 Then
Response.Redirect("~/Default.aspx")
Else
Try
If Request.Path.EndsWith(".pdf") Then
Dim client As New WebClient()
Dim buffer As [Byte]() = client.DownloadData(HttpContext.Current.Server.MapPath(Request.Path))
Response.ContentType = "application/pdf"
Response.AddHeader("content-length", buffer.Length.ToString())
Response.BinaryWrite(buffer)
Else
Using reader As New StreamReader(HttpContext.Current.Server.MapPath(Request.Path))
Response.Write(reader.ReadToEnd())
End Using
End If
Catch
Response.Redirect("~/Default.aspx")
End Try
End If
End Sub
Public ReadOnly Property IsReusable() As Boolean
' To enable pooling, return true here.
' This keeps the handler in memory.
Get
Return False
End Get
End Property
End Class