UPD: added MCVE.
这是一个教育任务。我必须使用SendMessage()
函数:
[DllImport("user32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd,
uint wMsg, UIntPtr wParam, IntPtr lParam);
我必须使两个不同的应用程序与GUI通信的消息。在收到"start"这样的消息后,1 app
必须开始每5秒向2 app
发送"Ask value"消息。2 app
向1 app
发送消息"send value",并附带一些数据。
1 app
是WinForms程序:
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
是控制台项目,但它需要System.Windows.Forms
引用:
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
}
}
}
}
和隐藏表单类:
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);
}
}
}
由于某些原因,这个程序表现得很奇怪。几乎每次2 app
没有收到"询问价值"的消息,有时checkSensors()
发送1-3个消息并停止。
怎么了?
两个HWnd都是正确的。
更新:I tried check error here:
public void checkSensors() {
while (true) {
SendMessage(secondAppHWnd, askMessageID, (UIntPtr)0, (IntPtr)0);
int error = Marshal.GetLastWin32Error();
System.Threading.Thread.Sleep(500);
}
}
看看。当执行SendMessage
时,这个线程被阻塞(这意味着SendMessage
没有完成)。在我关闭2 app
后,线程被解除阻塞,我得到164错误(ERROR_MAX_THRDS_REACHED:系统中不能创建更多的线程)。这是什么意思?
同时,补充道:
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);
}
它只是不断返回1400 ERROR_INVALID_WINDOW_HANDLE(我不发送任何消息在那一刻)。
所以我看起来完全不清楚。
更新2:如果我从WndProc()
调用它,一切工作:
SendMessage(secondAppHWnd, askMessageID, (UIntPtr)0, (IntPtr)0);
但是我需要每5秒从不同的线程发送此消息
所以,如果两个程序都是WinForms项目,它最终工作。我可以从2 app
运行控制台窗口并隐藏主窗口。