新手求指教 api调用

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Reflection;
using System.Diagnostics;
using System.IO;
using System.Text.RegularExpressions;namespace test
{
    public partial class Form1 : Form
    {
        //委托  
        public struct COPYDATASTRUCT
        {
            public IntPtr dwData;
            public int cbData;
            [MarshalAs(UnmanagedType.LPStr)]
            public string lpData;
        }        public delegate int HookProc(int nCode, int wParam, IntPtr lParam);        static int hHook = 0;
        public const int WH_KEYBOARD_LL = 13;
        //LowLevel键盘截获，如果是WH_KEYBOARD＝2，并不能对系统键盘截取，Acrobat Reader会在你截取之前获得键盘。  
        HookProc KeyBoardHookProcedure;
        //键盘Hook结构函数  
        [StructLayout(LayoutKind.Sequential)]
        public class KeyBoardHookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }
        #region DllImport
        //设置钩子  
        [DllImport("user32.dll")]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
        //抽掉钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);
        //调用下一个钩子 
        [DllImport("user32.dll")]
        public static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);        [DllImport("kernel32.dll")]
        public static extern int GetCurrentThreadId();        [DllImport("kernel32.dll")]
        public static extern IntPtr GetModuleHandle(string name);
        #endregion        #region 自定义事件
        public void Hook_Start()
        {
            // 安装键盘钩子  
            if (hHook == 0)
            {
                KeyBoardHookProcedure = new HookProc(KeyBoardHookProc);                //hHook = SetWindowsHookEx(2,  
                // KeyBoardHookProcedure,  
                // GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), GetCurrentThreadId());                  hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardHookProcedure, GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), 0);
                //如果设置钩子失败.  
                if (hHook == 0)
                {
                    Hook_Clear();
                    //throw new Exception("设置Hook失败!");  
                }
            }
        }        //取消钩子事件  
        public void Hook_Clear()
        {
            bool retKeyboard = true;
            if (hHook != 0)
            {
                retKeyboard = UnhookWindowsHookEx(hHook);
                hHook = 0;
            }
            //如果去掉钩子失败.  
            if (!retKeyboard) throw new Exception("UnhookWindowsHookEx failed.");
        }
        static int num = 0;
        //这里可以添加自己想要的信息处理  
        public static int KeyBoardHookProc(int nCode, int wParam, IntPtr lParam)
        {
            if (nCode >= 0)
            {
                KeyBoardHookStruct kbh = (KeyBoardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyBoardHookStruct));
                 if (kbh.vkCode != 0)
                {
                    num++;
                    MessageBox.Show(kbh.vkCode + " "+num);                }
                return 0;
            }
            return CallNextHookEx(hHook, nCode, wParam, lParam);
        }
        #endregion        public Form1()
        {
            InitializeComponent();
        }        private void button1_Click(object sender, EventArgs e)
        {
            Hook_Start();
        }        private void button2_Click(object sender, EventArgs e)
        {
            Hook_Clear();
        }
    }}
vs调试时红色部分调用一次 不调试时调用两次