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我正在尝试将结构化数据从我正在开发的 VB 2010 应用程序发送到现有库，该库期望将字符串转换为字节数组。我在将数据作为字节数组发送时遇到问题 - 我可以将应该转换为字节的纯字符串发送到我编写的测试程序。

这是两个应用程序。首先是监听进程：

Imports System.Runtime.InteropServices
Public Class frmTest

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
    If m.Msg = frmTest.WM_COPYDATA Then
        Dim data As CopyData
        Dim message As String

        ' get the data...
        data = CType(m.GetLParam(GetType(CopyData)), CopyData)

        message = data.lpData
        ' add the message
        txtTest.Text = message

        ' let them know we processed the message...
        m.Result = New IntPtr(1)
    Else
        MyBase.WndProc(m)
    End If
End Sub

Private Function UnicodeBytesToString(ByVal bytes() As Byte) As String

    Return System.Text.Encoding.Unicode.GetString(bytes)
End Function

Private Const WM_COPYDATA As Integer = &H4A

<StructLayout(LayoutKind.Sequential)> _
Private Structure CopyData
    Public dwData As IntPtr
    Public cbData As Integer
    Public lpData As String
End Structure
End Class

其次是发送数据的过程：

Imports System.Runtime.InteropServices
Imports System.Collections.Generic

Public Class frmMain

<StructLayout(LayoutKind.Sequential)> _
Private Structure CopyData
    Public dwData As IntPtr
    Public cbData As Integer
    Public lpData As String
End Structure

Private Declare Auto Function SendMessage Lib "user32" _
 (ByVal hWnd As IntPtr, _
  ByVal Msg As Integer, _
  ByVal wParam As IntPtr, _
  ByRef lParam As CopyData) As Boolean

Private Declare Auto Function FindWindow Lib "user32" _
 (ByVal lpClassName As String, _
  ByVal lpWindowName As String) As IntPtr

Private Const WM_COPYDATA As Integer = &H4A

Private Sub cmdSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSend.Click


    Dim ClientWindow As IntPtr
    Dim a() As System.Diagnostics.Process = System.Diagnostics.Process.GetProcesses

    For Each p In a
        Console.WriteLine(p.ProcessName)
        If p.ProcessName = "Listener" Then
            ClientWindow = p.MainWindowHandle
            Exit For
        End If
    Next


    ' make sure we found an active client window
    If Not ClientWindow.Equals(IntPtr.Zero) Then

        ' if there is text to send
        If txtText.Text.Length > 0 Then
            Dim message As String = txtText.Text
            Dim data As CopyData

            ' set up the data...
            data.lpData = message
            data.cbData = message.Length * Marshal.SystemDefaultCharSize

            ' send the data
            frmMain.SendMessage(ClientWindow, frmMain.WM_COPYDATA, Me.Handle, data)

        End If
    Else
        MsgBox("Could Not Find Active Client Window.")
    End If
End Sub

Private Function UnicodeStringToBytes(
ByVal str As String) As Byte()

    Return System.Text.Encoding.Unicode.GetBytes(str)
End Function

End Class

This all works but if I change 'Public lpData As String' to 'Public lpData As Byte()' in both and then amend 'data.lpData = message' to 'data.lpData = UnicodeStringToBytes(message)' in the sender process and 'message = data.lpData' to 'message = UnicodeBytesToString(data.lpData)' in the listener process it crashes.

How can I send a string encoded as a byte array from the sender to the listener so that the listener can decode it back to a string ?

I realise it would be easier to send the string as a string but the existing library needs it as a byte array so I'm trying to get my sender working against this test listener where I can see what's happening.

Thanks in advance !

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1 回答 1

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Variable-length arrays in structures are always a pain.

Declare lpData as IntPtr in both applications.

Then in the sending app:

' set up the data...
Dim string_bytes = UnicodeStringToBytes(message)

Dim pinned = GCHandle.Alloc(string_bytes, GCHandleType.Pinned)
Try
    data.dwData = New IntPtr(message.Length)
    data.cbData = string_bytes.Length
    data.lpData = pinned.AddrOfPinnedObject()

    ' send the data
    frmMain.SendMessage(ClientWindow, frmMain.WM_COPYDATA, Me.Handle, data)
Finally
    If pinned.IsAllocated Then pinned.Free()
End Try

In the receiving app:

' get the data...
data = CType(m.GetLParam(GetType(CopyData)), CopyData)

Dim message(0 To data.cbData - 1) As Byte
Marshal.Copy(data.lpData, message, 0, data.cbData)

' add the message
txtTest.Text = UnicodeBytesToString(message)
于 2013-03-30T10:37:15.097 回答