如何让C#计时器在创建它的同一个线程上执行？

Question

我想IMessageFilter在Excel Addin 上启用我必须写入excel.我从这里举了一些例子说:

消息过滤器是每个线程,所以我们将此线程注册为消息过滤器(不是创建加载项的主线程 - 因为这是Excel的主线程

我的问题是,当一个计时器过去导致从ThreadPool线程调用写入方法时,我的系统写入excel ,因为它IMessageFilter不能访问RetryRejectedCall部分IMessageFilter,因为它存在于调用者线程而不是执行的生成者之间.计时器.

所以,我的问题是:有没有办法可以强制计时器的Elapsed事件在初始化计时器的同一个线程上运行？

编辑:

我的问题是,如何IMessageFilter在抛出拒绝/忙碌时捕获excel错误？

谢谢

Answer 1

您可以使用Timer.SynchronizingObjectproperty来封送在间隔过去时发出的事件处理程序调用.

这是来自MSDN:

当Elapsed事件由可视Windows窗体组件(如按钮)处理时,通过系统线程池访问组件可能会导致异常或者可能无法正常工作.通过将SynchronizingObject设置为Windows窗体组件来避免此影响,这会导致处理Elapsed事件的方法在创建组件的同一线程上调用.

假设您正在使用WinFrom,并且您正在从主窗体中创建计时器实例:

System.Timers.Timer t = new System.Timers.Timer();
t.SynchronizingObject = this;
t.Elapsed += t_Elapsed;
t.Start();

Answer 2

完整答案如下：

问题：将数据写入 Excel 的类无法处理来自 Excel 的“忙/拒绝”响应消息。

解决方案：按照此处IMessageFilter所述实现接口

IMessageFilter定义（来自链接）：

namespace ExcelAddinMessageFilter
{
        [StructLayout(LayoutKind.Sequential, Pack = 4)]
        public struct INTERFACEINFO
        {
            [MarshalAs(UnmanagedType.IUnknown)]
            public object punk;
            public Guid iid;
            public ushort wMethod;
        }

        [ComImport, ComConversionLoss, InterfaceType((short)1),
        Guid("00000016-0000-0000-C000-000000000046")]
        public interface IMessageFilter
        {
            [PreserveSig, MethodImpl(MethodImplOptions.InternalCall,
                MethodCodeType = MethodCodeType.Runtime)]
            int HandleInComingCall([In] uint dwCallType, [In] IntPtr htaskCaller,
                [In] uint dwTickCount,
                [In, MarshalAs(UnmanagedType.LPArray)] INTERFACEINFO[]
                lpInterfaceInfo);

            [PreserveSig, MethodImpl(MethodImplOptions.InternalCall,
                MethodCodeType = MethodCodeType.Runtime)]
            int RetryRejectedCall([In] IntPtr htaskCallee, [In] uint dwTickCount,
                [In] uint dwRejectType);

            [PreserveSig, MethodImpl(MethodImplOptions.InternalCall,
                MethodCodeType = MethodCodeType.Runtime)]
            int MessagePending([In] IntPtr htaskCallee, [In] uint dwTickCount,
                [In] uint dwPendingType);
        }
    }

IMessageFilter我的课程的实现部分（参见链接）：

#region IMessageFilter Members

        int ExcelAddinMessageFilter.IMessageFilter.
            HandleInComingCall(uint dwCallType, IntPtr htaskCaller, uint dwTickCount, ExcelAddinMessageFilter.INTERFACEINFO[] lpInterfaceInfo)
        {
            // We're the client, so we won't get HandleInComingCall calls.
            return 1;
        }

        int ExcelAddinMessageFilter.IMessageFilter.
        RetryRejectedCall(IntPtr htaskCallee, uint dwTickCount, uint dwRejectType)
        {
            // The client will get RetryRejectedCall calls when the main Excel
            // thread is blocked. We can handle this by attempting to retry
            // the operation. This will continue to fail so long as Excel is 
            // blocked.
            // As an alternative to simply retrying, we could put up
            // a dialog telling the user to close the other dialog (and the
            // new one) in order to continue - or to tell us if they want to
            // abandon this call
            // Expected return values:
            // -1: The call should be canceled. COM then returns RPC_E_CALL_REJECTED from the original method call.
            // Value >= 0 and <100: The call is to be retried immediately.
            // Value >= 100: COM will wait for this many milliseconds and then retry the call.
            return 1;
        }

        int ExcelAddinMessageFilter.IMessageFilter.
            MessagePending(IntPtr htaskCallee, uint dwTickCount, uint dwPendingType)
        {
            return 1;
        }

        #endregion

定义和实现接口后IMessageFilter，我设置了 STAThread和 a，Timers.Timer如下所示：

线：

thread = new Thread(WriteToExcel);
thread.SetApartmentState(ApartmentState.STA);

定时器：

timer = new System.Timers.Timer();
timer.Interval = 2000;
timer.Elapsed += new ElapsedEventHandler(StartSTAThread_Handler);

其中StartSTAThread_Handler定义为：

void StartSTAThread_Handler(object source, ElapsedEventArgs e)
{
     thread.Start();
     thread.Join();
     thread = null;
}

该线程调用我用来写入 Excel 的方法，并使用IMessageFilter上述接口处理拒绝的消息。我要做的最后一件事是完全限定 excel OM 引用，即；代替：

Excel.Range rng = app.ActiveSheet.Range["range_name"];
rng.Copy(); // ERRROR: message filter's RetryRejectedCall is NOT called

我必须使用完全限定的引用：

app.ActiveSheet.Range["range_name"].Copy // OK: calls RetryRejectedCall when excel dialog etc is showing

虽然这似乎适合我的需要，但它似乎确实与另一张海报所描述的“两点规则”相矛盾......