使用SendMessage將消息循環發送到不同的procces（）

Question

UPD：添加了MCVE。

這是一項教育任務。我必須使用SendMessage()功能：

[DllImport("user32.dll")] 
public static extern IntPtr SendMessage(IntPtr hWnd, 
    uint wMsg, UIntPtr wParam, IntPtr lParam); 

我有信息，以與GUI communicationg兩個不同的應用。在得到諸如「開始」1 app之類的消息之後，必須每5秒開始發送消息「請求值」至2 app。並且2 app發送到1 app消息「發送值」與一些數據。

1 app是的WinForms方案：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Linq; 
using System.Text; 
using System.Threading; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.Runtime.InteropServices; 

namespace Oven_Monitor 
{ 
    public partial class Form1 : Form 
    { 
     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)] 
     public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); 

     [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] 
     public static extern int GetCurrentProcessId(); 

     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] 
     static extern uint RegisterWindowMessage(string lpString); 

     [DllImport("user32.dll")] 
     public static extern IntPtr SendMessage(IntPtr hWnd, uint wMsg, UIntPtr wParam, IntPtr lParam); 

     private uint askMessageID  = RegisterWindowMessage("Ask value"); 
     private uint dataMessageID  = RegisterWindowMessage("Send value"); 
     private uint registerMessageID = RegisterWindowMessage("Register sensor"); 

     public Form1() { 
      InitializeComponent(); 
      this.Text = "Really rare title"; 
     } 

     public void checkSensors() { 
      while (true) { 
       SendMessage(secondAppHWnd, askMessageID, (UIntPtr)0, (IntPtr)0); 
       System.Threading.Thread.Sleep(500); 
      } 
     } 

     private IntPtr secondAppHWnd; 

     protected override void WndProc(ref Message m) { 
      if (m.Msg == registerMessageID) { 
       secondAppHWnd = m.LParam; 
       Thread tr = new Thread(checkSensors); 
       tr.Start(); 
      } else if (m.Msg == dataMessageID) { 
       //do some stuff 
      } 
      base.WndProc(ref m); 
     } 
    } 
} 

2 app是控制檯項目，但它需要System.Windows.Forms referens：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading; 
using System.Threading.Tasks; 
using System.Windows; 
using System.Windows.Forms; 
using System.Runtime.InteropServices; 

namespace HeatSensor 
{ 
    class Program 
    { 
     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)] 
     public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); 

     static void Main(string[] args) 
     { 
      IntPtr mainAppHandle = FindWindow(null, "Really rare title"); 
      while (mainAppHandle == IntPtr.Zero) 
      { 
       Console.ReadKey(); 
       mainAppHandle = FindWindow(null, "Really rare title"); 
      } 
      HiddenForm form = new HiddenForm(mainAppHandle); 

      while (true) //it's actually not infinit 
      { 
       //do some stuff 
      } 
     } 
    } 
} 

及隱藏表單類：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.Runtime.InteropServices; 

namespace HeatSensor 
{ 
    public partial class HiddenForm : Form 
    { 
     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)] 
     public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); 

     [DllImport("user32.dll")] 
     public static extern IntPtr SendMessage(IntPtr hWnd, uint wMsg, UIntPtr wParam, IntPtr lParam); 

     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] 
     static extern uint RegisterWindowMessage(string lpString); 

     static private IntPtr mainAppHandle; 

     public HiddenForm(IntPtr mainAppHWnd) 
     { 
      InitializeComponent(); 
      mainAppHandle = mainAppHWnd; 
      string title = System.DateTime.Now.ToLongDateString(); 
      title += System.DateTime.Now.ToLongTimeString(); 
      title += System.DateTime.Now.Ticks.ToString(); 
      this.Text = title; 
      this.CreateHandle(); 
      int currentWindowHandle = (int)FindWindow(null, title); 
      SendMessage(mainAppHandle, RegisterWindowMessage("Register sensor"), 
       (UIntPtr)0, currentWindowHandle); 
     } 

     private uint askMessageID = RegisterWindowMessage("Ask value"); 
     private uint dataMessageID = RegisterWindowMessage("Send value"); 
     private uint registerMessageID = RegisterWindowMessage("Register sensor"); 

     protected override void WndProc(ref Message m) 
     { 
      if (m.Msg == askMessageID) 
      { 
       SendMessage(mainAppHandle, dataMessageID, (UIntPtr)1, (IntPtr)1); 
      } 
      base.WndProc(ref m); 
     } 
    } 
} 

出於某種原因，這個程序行爲很奇怪。幾乎每次2 app都沒有收到「詢問價值」消息，有時checkSensors()發送1-3條消息並停止。

有什麼不對？

這兩個HWnd都是正確的。

---

更新：我試圖檢查錯誤的位置：

public void checkSensors() { 
    while (true) { 
     SendMessage(secondAppHWnd, askMessageID, (UIntPtr)0, (IntPtr)0); 
     int error = Marshal.GetLastWin32Error();     
     System.Threading.Thread.Sleep(500); 
    } 
} 

看看。當SendMessage被執行時，這個線程被阻塞了（什麼意思，SendMessage沒有被弄錯，當我關閉2 app之後，線程被解除了阻塞，並且我得到了164個錯誤（ERROR_MAX_THRDS_REACHED：系統中沒有更多的線程可以被創建）。 ？意味着

此外，補充說：

protected override void WndProc(ref Message m) 
      { 
       //here is all message checks 
       int erro2r = Marshal.GetLastWin32Error(); 
       if (erro2r != 0) { 
        int j; //stop to debug here 
       } 
       base.WndProc(ref m); 
      } 

它只是不斷地返回1400 ERROR_INVALID_WINDOW_HANDLE（我沒有在那一刻發送任何消息）

因此，它看起來完全以我不清楚

。

---

更新2：如果我從WndProc()調用它，一切正常：

SendMessage(secondAppHWnd, askMessageID, (UIntPtr)0, (IntPtr)0); 

，但我需要從不同的線程發送此消息每5秒。

Answer 1

所以，如果兩個程序都是WinForms項目，它終於可以工作。我可以從2 app運行控制檯窗口並隱藏主窗口。