如何使用后期绑定获取Excel实例?

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我在用

[DllImport("Oleacc.dll")]
static extern int AccessibleObjectFromWindow(
int hwnd, 
uint dwObjectID, 
byte[] riid,
ref Excel.Window ptr);

若要使用他的句柄获取Excel实例,我将从excel实例的进程ID中获取该句柄。

这就是我使用这些函数时的样子。

const uint OBJID_NATIVEOM = 0xFFFFFFF0;
Guid IID_IDispatch = new Guid("{00020400-0000-0000-C000-000000000046}");
Excel.Window ptr = null;  
int hr = AccessibleObjectFromWindow(hwndChild, OBJID_NATIVEOM, 
          IID_IDispatch.ToByteArray(), ref ptr);

Object objApp = ptr.Application;

这种代码的平静很好用,但唯一的问题是我必须添加一个引用到Office 2003主互操作程序集。

函数中的最后一个参数是为什么我需要添加对Pias的引用,所以我的问题是,是否有一种避免使用Interop Assembies的方法,我尝试过使用后期绑定,但可能我做错了,因为我一直无法使它工作。

提问于
用户回答回答于

第一:在C#中后期绑定是一个相当痛苦的问题。最好避免。第二:在C#中后期绑定是一种痛苦。用PIA!

好的,尽管如此,以下是使用延迟绑定所需的操作:删除对Office 2003 PIA的引用,然后添加一个COM导入所需的接口。AccessibleObjectFromWindow,即Excel.Window接口:

[Guid("00020893-0000-0000-C000-000000000046")]
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface ExcelWindow
{
}

可以使用以下工具检索此接口反射器(或简单地按下类型上的F12Excel.Window当对ExcelPIA的引用仍在您的项目中时)

完成后,将不得不修改AccessibleObjectFromWindow与进口的ExcelWindow接口:

[DllImport("Oleacc.dll")]
static extern int AccessibleObjectFromWindow(int hwnd, uint dwObjectID, byte[] riid, out ExcelWindow ptr);

最后,必须使用反射获取Excel.Application对象的ExcelWindow目的:

object xlApp = ptr.GetType().InvokeMember("Application", BindingFlags.GetProperty, null, ptr, null);

如果代码要对Excel的OM进行大量调用,则使用VB可能更容易Option Strict关闭(或等待C#4.0;-)。或者,如果不想改变C#,最好为后期绑定调用创建一个包装类。


全样本

下面是一个功能齐全的示例:

using System;
using System.Globalization;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;

namespace ExcelLateBindingSample
{
    /// <summary>
    /// Interface definition for Excel.Window interface
    /// </summary>
    [Guid("00020893-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface ExcelWindow
    {
    }

    /// <summary>
    /// This class is needed as a workaround to http://support.microsoft.com/default.aspx?scid=kb;en-us;320369
    /// Excel automation will fail with the follwoing error on systems with non-English regional settings:
    /// "Old format or invalid type library. (Exception from HRESULT: 0x80028018 (TYPE_E_INVDATAREAD))" 
    /// </summary>
    class UILanguageHelper : IDisposable
    {
        private CultureInfo _currentCulture;

        public UILanguageHelper()
        {
            // save current culture and set culture to en-US 
            _currentCulture = System.Threading.Thread.CurrentThread.CurrentCulture;
            System.Threading.Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
        }

        public void Dispose()
        {
            // reset to original culture 
            System.Threading.Thread.CurrentThread.CurrentCulture = _currentCulture;
        }
    }

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

        [DllImport("Oleacc.dll")]
        static extern int AccessibleObjectFromWindow(int hwnd, uint dwObjectID, byte[] riid, out ExcelWindow ptr);

        public delegate bool EnumChildCallback(int hwnd, ref int lParam);

        [DllImport("User32.dll")]
        public static extern bool EnumChildWindows(int hWndParent, EnumChildCallback lpEnumFunc, ref int lParam);

        [DllImport("User32.dll")]
        public static extern int GetClassName(int hWnd, StringBuilder lpClassName, int nMaxCount);

        public static bool EnumChildProc(int hwndChild, ref int lParam)
        {
            StringBuilder buf = new StringBuilder(128);
            GetClassName(hwndChild, buf, 128);
            if (buf.ToString() == "EXCEL7")
            {
                lParam = hwndChild;
                return false;
            }
            return true;
        }

        static void Main(string[] args)
        {
            // Use the window class name ("XLMAIN") to retrieve a handle to Excel's main window.
            // Alternatively you can get the window handle via the process id:
            // int hwnd = (int)Process.GetProcessById(excelPid).MainWindowHandle;
            //
            int hwnd = (int)FindWindow("XLMAIN", null); 

            if (hwnd != 0)
            {
                int hwndChild = 0;

                // Search the accessible child window (it has class name "EXCEL7") 
                EnumChildCallback cb = new EnumChildCallback(EnumChildProc);
                EnumChildWindows(hwnd, cb, ref hwndChild);

                if (hwndChild != 0)
                {
                    // We call AccessibleObjectFromWindow, passing the constant OBJID_NATIVEOM (defined in winuser.h) 
                    // and IID_IDispatch - we want an IDispatch pointer into the native object model.
                    //
                    const uint OBJID_NATIVEOM = 0xFFFFFFF0;
                    Guid IID_IDispatch = new Guid("{00020400-0000-0000-C000-000000000046}");
                    ExcelWindow ptr;

                    int hr = AccessibleObjectFromWindow(hwndChild, OBJID_NATIVEOM, IID_IDispatch.ToByteArray(), out ptr);

                    if (hr >= 0)
                    {
                        // We successfully got a native OM IDispatch pointer, we can QI this for
                        // an Excel Application using reflection (and using UILanguageHelper to 
                        // fix http://support.microsoft.com/default.aspx?scid=kb;en-us;320369)
                        //
                        using (UILanguageHelper fix = new UILanguageHelper())
                        {
                            object xlApp = ptr.GetType().InvokeMember("Application", BindingFlags.GetProperty, null, ptr, null);

                            object version = xlApp.GetType().InvokeMember("Version", BindingFlags.GetField | BindingFlags.InvokeMethod | BindingFlags.GetProperty, null, xlApp, null);
                            Console.WriteLine(string.Format("Excel version is: {0}", version));
                        }
                    }
                }
            }
        }
    }
}

在VB中,如果没有PIA,这将是相同的解决方案(注意,OM调用的可读性要高得多;但是,访问OM的代码将是相同的):

Option Strict Off

Imports System.Globalization
Imports System.Runtime.InteropServices
Imports System.Text

Module ExcelLateBindingSample

    ''' <summary>
    ''' Interface definition for Excel.Window interface
    ''' </summary>
    <Guid("00020893-0000-0000-C000-000000000046"), _
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch)> _
    Public Interface ExcelWindow
    End Interface

    ''' <summary>
    ''' This class is needed as a workaround to http://support.microsoft.com/default.aspx?scid=kb;en-us;320369
    ''' Excel automation will fail with the follwoing error on systems with non-English regional settings:
    ''' "Old format or invalid type library. (Exception from HRESULT: 0x80028018 (TYPE_E_INVDATAREAD))" 
    ''' </summary>
    Class UILanguageHelper
        Implements IDisposable

        Private _currentCulture As CultureInfo

        Public Sub New()
            ' save current culture and set culture to en-US 
            _currentCulture = System.Threading.Thread.CurrentThread.CurrentCulture
            System.Threading.Thread.CurrentThread.CurrentCulture = New CultureInfo("en-US")
        End Sub

        Public Sub Dispose() Implements System.IDisposable.Dispose
            'reset to original culture 
            System.Threading.Thread.CurrentThread.CurrentCulture = _currentCulture
        End Sub

    End Class

    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
    Private Function FindWindow(ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
    End Function

    <DllImport("Oleacc.dll")> _
    Private Function AccessibleObjectFromWindow(ByVal hwnd As Integer, ByVal dwObjectID As UInt32, ByVal riid() As Byte, ByRef ptr As ExcelWindow) As Integer
    End Function

    Public Delegate Function EnumChildCallback(ByVal hwnd As Integer, ByRef lParam As Integer) As Boolean

    <DllImport("User32.dll")> _
    Public Function EnumChildWindows(ByVal hWndParent As Integer, ByVal lpEnumFunc As EnumChildCallback, ByRef lParam As Integer) As Boolean
    End Function

    <DllImport("User32.dll")> _
    Public Function GetClassName(ByVal hWnd As Integer, ByVal lpClassName As StringBuilder, ByVal nMaxCount As Integer) As Integer
    End Function

    Public Function EnumChildProc(ByVal hwndChild As Integer, ByRef lParam As Integer) As Boolean
        Dim buf As New StringBuilder(128)
        GetClassName(hwndChild, buf, 128)
        If buf.ToString() = "EXCEL7" Then
            lParam = hwndChild
            Return False
        End If
        Return True
    End Function

    Sub Main()
        ' Use the window class name ("XLMAIN") to retrieve a handle to Excel's main window.
        ' Alternatively you can get the window handle via the process id:
        ' Dim hwnd As Integer = CInt(Process.GetProcessById(excelPid).MainWindowHandle);
        '
        Dim hwnd As Integer = CInt(FindWindow("XLMAIN", Nothing))

        If hwnd <> 0 Then
            Dim hwndChild As Integer = 0

            ' Search the accessible child window (it has class name "EXCEL7") 
            Dim cb As New EnumChildCallback(AddressOf EnumChildProc)
            EnumChildWindows(hwnd, cb, hwndChild)

            If hwndChild <> 0 Then
                ' We call AccessibleObjectFromWindow, passing the constant OBJID_NATIVEOM (defined in winuser.h) 
                ' and IID_IDispatch - we want an IDispatch pointer into the native object model.
                '
                Const OBJID_NATIVEOM As UInteger = &HFFFFFFF0&
                Dim IID_IDispatch As New Guid("{00020400-0000-0000-C000-000000000046}")
                Dim ptr As ExcelWindow

                Dim hr As Integer = AccessibleObjectFromWindow(hwndChild, OBJID_NATIVEOM, IID_IDispatch.ToByteArray(), ptr)

                If hr >= 0 Then
                    ' We successfully got a native OM IDispatch pointer, we can QI this for
                    ' an Excel Application using reflection (and using UILanguageHelper to 
                    ' fix http://support.microsoft.com/default.aspx?scid=kb;en-us;320369)
                    '
                    Using fixCrash As New UILanguageHelper
                        Console.WriteLine(String.Format("Excel version is: {0}", ptr.Application.Version))
                    End Using
                End If
            End If
        End If

    End Sub

End Module
用户回答回答于

使用AccessibleObjectFromWindow的以下定义:

    [DllImport("Oleacc.dll")]
    private static extern int AccessibleObjectFromWindow(
        int hwnd, uint dwObjectID,
        byte[] riid,
        [MarshalAs(UnmanagedType.IUnknown)]ref object ptr);

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