C# 多个程序实例只允许一个及进程间通信sendMessage

发送方：
static class Program
{
#region 只运行一个实例
public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);

        //遍历与当前进程名称相同的进程列表        foreach (Process process in processes)        {            //Ignore the current process            if (process.Id != current.Id)            {                //Make sure that the process is running from the exe file.                if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)                {                    //Return the other process instance.                    //MessageBox.Show("已经有了！");                    return process;                }            }        }        return null;    }    #endregion    [DllImport("User32.dll")]    private static extern bool ShowWindowAsync(System.IntPtr hWnd, int cmdShow);    [DllImport("User32.dll")]    private static extern bool SetForegroundWindow(System.IntPtr hWnd);    private static void HandleRunningInstance(Process instance)    {        //MessageBox.Show("该应用系统已经在运行！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);        ShowWindowAsync(instance.MainWindowHandle, 1); //调用api函数，正常显示窗口         SetForegroundWindow(instance.MainWindowHandle); //将窗口放置最前端。    }    #region sendMessage    [StructLayout(LayoutKind.Sequential)]    public struct COPYDATASTRUCT    {        public IntPtr dwData;        public int cbData;        public IntPtr lpData;    }    //Win32 API函数：    [DllImport("User32.dll", EntryPoint = "SendMessage")]    private static extern int SendMessage(IntPtr hWnd, int msg, int wP, ref COPYDATASTRUCT lParam);    private const int WM_COPYDATA = 0x004A;    #endregion    public static bool SendString(IntPtr hWnd, string str)    {        try        {            byte[] sarr = System.Text.Encoding.Default.GetBytes(str);            var ptr = Marshal.StringToHGlobalUni(str);            COPYDATASTRUCT cds = new COPYDATASTRUCT();            cds.dwData = ptr;            cds.cbData = sarr.Length;            cds.lpData = Marshal.AllocHGlobal(sarr.Length);            Marshal.Copy(sarr, 0, cds.lpData, sarr.Length);            SendMessage(hWnd, WM_COPYDATA, 0, ref cds);            //MessageBox.Show("我在sendMesasage后");            return true;        }        catch (Exception e) { return false; }    }    /// <summary>    /// 应用程序的主入口点。    /// </summary>    [STAThread]    static void Main(string[] path)    {        //MessageBox.Show("我在这儿"+path.Length);        Process instance = RunningInstance();        if (instance == null)        {            Application.EnableVisualStyles();            Application.SetCompatibleTextRenderingDefault(false);            //MessageBox.Show("我在这儿null");            Thread.CurrentThread.CurrentUICulture = System.Globalization.CultureInfo.CurrentCulture;            ChineseStringLocalizer.Register();            Localizer.SetStringLocalizer(new ChineseStringLocalizer());            var catalog = new TypeCatalog(                typeof(SettingsService),                typeof(CommandService),                typeof(StatusService),                typeof(ControlHostService),                typeof(StandardFileExitCommand),                typeof(DocumentRegistry),                typeof(ContextRegistry),                typeof(DefaultTabCommands),                typeof(MyOutputs),                     // passes messages to all log writers                typeof(ResFileInfo),                typeof(FileTreeView),                typeof(FolderViewer),                typeof(ResListView),                //typeof(ShortcutKey),                typeof(FileViewer),                typeof(MyOutputService),                    typeof(Editor)                //,typeof(StandardEditCommands)                );            var container = new CompositionContainer(catalog);            var toolStripContainer = new ToolStripContainer();            var mainForm = new ResCopyTool.MainForm(toolStripContainer)            {                Text = "美术资源移动工具".Localize(),                Icon = GdiUtil.CreateIcon(ResourceUtil.GetImage(Sce.Atf.Resources.AtfIconImage))            };            var batch = new CompositionBatch();            //MessageBox.Show("我是窗口"+path);            mainForm.Args = path;            batch.AddPart(mainForm);            //batch.AddPart(new WebHelpCommands("http://192.168.2.121:8090/pages/viewpage.action?pageId=14745613".Localize()));            container.Compose(batch);            container.InitializeAll();            Application.Run(mainForm);            container.Dispose();        }        else        {            //MessageBox.Show("我在这儿not null");            HandleRunningInstance(instance);            IntPtr hWnd = instance.MainWindowHandle; //获取ProcessCommunication.exe主窗口句柄            SendString(hWnd, path[0]);            instance.Start();        }    }

接收方：
[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT
{
public IntPtr dwData;
public int cbData;
public IntPtr lpData;
}

    //Win32 API函数：    [DllImport("User32.dll", EntryPoint = "SendMessage")]    private static extern int SendMessage(IntPtr hWnd, int msg, int wP, ref COPYDATASTRUCT lParam);    private const int WM_COPYDATA = 0x004A;    protected override void DefWndProc(ref Message m)    {        switch (m.Msg)        {            //接收自定义消息MYMESSAGE，并显示其参数            case WM_COPYDATA:                {                    //MessageBox.Show("我在收到  sendMesasage前");                    //My_lParam a = new My_lParam();                    ////Type t = a.GetType();                    //a = (My_lParam)m.GetLParam(typeof(My_lParam));                    //Marshal.PtrToStringAnsi(m.LParam)                    //this.textBox1.Text = a.s[0];                    COPYDATASTRUCT mystr = new COPYDATASTRUCT();                    Type mytype = mystr.GetType();                    mystr = (COPYDATASTRUCT)m.GetLParam(mytype);                    //this.textBox1.Text = Marshal.PtrToStringUni(mystr.lpData);Marshal.                    byte[] bt = new byte[mystr.cbData];                    Marshal.Copy(mystr.lpData, bt, 0, bt.Length);                    string tmp = System.Text.Encoding.Default.GetString(bt);                    m_args[0] = tmp;                    //MessageBox.Show("我在收到  sendMesasage后");                    OnReceiveMsgChanged.Raise(this, new OnReceiveMsgArgs(tmp));                }                break;            default:                base.DefWndProc(ref m);                break;        }    }