声明的dll函数的行为不一致

为什么我会 GetRawData 声明的函数在从我的VB.NET应用程序调用时返回正确的值,但在从我的ASP.NET页调用时返回零?

除了类类型差异(窗体/页)和调用事件处理程序(Form1_Load、Page_Load)之外,代码完全相同。

注意:在实际代码中,dll和raw data file分别是我的dll和原始数据文件的绝对文件名。

注意:该dll文件不是由Visual Studio创建的。

Fuff1.VB

Public Class Form1

    Declare Auto Function GetRawData Lib "#DLL#" (ByVal filename() As Byte, _
                                                  ByVal byteArray() As Byte, _
                                                  ByVal length As Int32) As Int32


    Private Sub Form1_Load(ByVal sender As System.Object, _
                           ByVal e As System.EventArgs) Handles MyBase.Load

        Dim buffer(10485760) As Byte
        Dim msg As String, length As Integer = 10485760
        Dim filename As String = "#RAWDATAFILE#"
        length = GetRawData(Encoding.Default.GetBytes(filename), buffer, length)

Abx.VB

Partial Public Class _Default
    Inherits System.Web.UI.Page

    Declare Auto Function GetRawData Lib "#DLL#" (ByVal filename() As Byte, _
                                                  ByVal byteArray() As Byte, _
                                                  ByVal length As Int32) As Int32


    Protected Sub Page_Load(ByVal sender As Object, _
                            ByVal e As System.EventArgs) Handles Me.Load

        Dim buffer(10485760) As Byte
        Dim msg As String, length As Integer = 10485760
        Dim filename As String = "#RAWDATAFILE#"
        length = GetRawData(Encoding.Default.GetBytes(filename), buffer, length)