C#中利用Win API调用外部程序

Windows窗口、控件的任何操作，是通过消息事件来完成。在我们自己的程序中，只要能准确地找到相应功能所在的窗口或控件的句柄Handle，发出相应的消息，即可完成相应任务。关键在于两个地方：一是找准句柄，二是找对消息。
    推荐分析一个窗体（控件）的句柄或消息的工具：SPY++，这在Visual Studio Tools中有，操作起来很简单。

    C#中实现外部程序调用，可以通过封装User32.dll中sendmessage等函数来实现。我已将常用的功能封装成一个类：

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace MuliCall
{
    class WinApi
    {
        #region  宏定义

        public const int WM_KEYDOWN = 0x100;
        public const int WM_KEYUP = 0x101;
        public const int VK_CONTROL = 0x11;
        public const int VK_F5 = 0x74;
        public const int KEYEVENTF_KEYUP = 0x2;
        public const int VK_MENU = 0x12;
        public const int WM_SETTEXT = 0xC;
        public const int WM_CLEAR = 0x303;
        public const int BN_CLICKED = 0;
        public const int WM_LBUTTONDOWN = 0x201;
        public const int WM_LBUTTONUP = 0x202;
        public const int WM_CLOSE = 0x10;
        public const int WM_COMMAND = 0x111;
        public const int WM_SYSKEYDOWN = 0x104;

        #endregion

        public delegate bool EnumChildWindowsProc(IntPtr hwnd, int lParam);        

        #region  WinAPI定义

        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(
            int hWnd, // handle to destination window
            int Msg, // message
            int wParam, // first message parameter
             int lParam // second message parameter
        );
        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        public static extern int SendTxtMessage(
            int hWnd, // handle to destination window
            int Msg, // message
            int wParam, // first message parameter
            char[] lParam
            // int  lParam // second message parameter
        );
        [DllImport("user32.dll", EntryPoint = "PostMessage")]
        public static extern int PostMessage(
            int hwnd,
            int wMsg,
            int wParam,
            int lParam
        );

        [DllImport("user32.dll", EntryPoint = "FindWindow")]
        public static extern int FindWindow(
            string lpClassName,
            string lpWindowName
        );
        [DllImport("user32.dll", EntryPoint = "FindWindowEx")]
        public static extern int FindWindowEx(
            int hwndParent,

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