VB 2010發送消息：發送二進制數據到另一個應用程序

Question

我想從一個VB 2010應用程序發送結構化數據到現有的庫，該庫需要將字符串轉換爲字節數組。我在將數據作爲字節數組發送時遇到問題 - 我可以將應該轉換爲字節的純字符串發送到我編寫的測試程序。

這是兩個應用程序。首先監聽器進程：

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 

這一切工作，但如果我改變「公共的lpData作爲字符串」到「公共的lpData爲字節（）」中：

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，發送的數據處理然後在偵聽器進程中將'data.lpData = message'修改爲'data.lpData = UnicodeStringToBytes（message）'並將'message = data.lpData'修改爲'message = UnicodeBytesToString（data.lpData）'崩潰。

如何發送字符串作爲字節數組從發送方發送到偵聽器，以便偵聽器可以將其解碼回字符串？

我意識到將字符串作爲字符串發送會更容易，但現有的庫需要它作爲字節數組，所以我試圖讓我的發件人對這個測試偵聽器工作，我可以看到發生了什麼。

在此先感謝！

Answer 1

結構中的變長陣列總是很痛苦。

在兩個申請中聲明lpData爲IntPtr。

然後在發送應用程序：

' 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 

在接收應用程序：

' 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)