为什么安装WH_GETMESSAGE全局钩子只得到一次消息,同样的代码,安装成键盘钩子能正常运行

   我安装上WH_GETMESSAGE全局钩子只能得到一次消息.请大家帮帮忙看一下吧!我把源程序放入附件里了.
   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.IO;
using System.Reflection;
using System.Diagnostics;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {

        #region
        public static int i = 0;
       StreamWriter sw;
       // StreamWriter sw1;
       [StructLayout(LayoutKind.Sequential)]
        public class Msg
        {
            public IntPtr hwnd;
            public IntPtr lparam;
            public uint message;
            public Point pt;
            public uint time;
        }
        [StructLayout(LayoutKind.Sequential)]
        public class KeyboardHookStruct
        {
            public int vkCode; //表示一个在1到254间的虚似键盘码
            public int scanCode; //表示硬件扫描码
            public int flags;
            public int time;
            public int dwExtraInfo;
        }
        // 安装钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
        [DllImport("kernel32.dll")]
        static extern int GetCurrentThreadId();
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);
        [DllImport("imm32.dll")]
        static extern IntPtr ImmGetContext(IntPtr hWnd);
        [DllImport("imm32.dll")]
        static extern int ImmGetCompositionString(IntPtr hIMC, int dwIndex, StringBuilder lpBuf, int dwBufLen);
        private const int GCS_RESULTSTR = 2048;
        private const int GCS_RESURTREADSTR = 0x0200;
        private const int WM_IME_COMPOSITION = 271;
        private const int WM_CHAR = 258;
        private const int WM_KEYDOWN   = 0x0100;
        private const int WM_KEYUP   = 0x0101;
        public delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
        static int hKeyboardHook = 0;
        HookProc KeyboardHookProcedure;
        public Form1()
        {
            InitializeComponent();
        }
        #endregion

        //start hook
        private void button1_Click(object sender, EventArgs e)
        {
            HookStart();
        }
        private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
        {


             IntPtr j=lParam;
            sw = new StreamWriter(@"C:\Documents and Settings\Administrator\桌面\键盘记录信息.txt", true);
            sw.Write(j.ToString()+"\r\n");
            sw.Close();


             return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
        }
        //put hook
        public void HookStart()
        {
            if (hKeyboardHook == 0)
            {
                Process p = Process.GetCurrentProcess();
                // 创建HookProc实例
                KeyboardHookProcedure = new HookProc(KeyboardHookProc);
                // 设置线程钩子

                   hKeyboardHook = SetWindowsHookEx(3, KeyboardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().ManifestModule),0);

                // 如果设置钩子失败
                if (hKeyboardHook == 0)
                {

                    throw new Exception("SetWindowsHookEx failed.");
                }
            }
        }
        //end hook
        private void button2_Click(object sender, EventArgs e)
        {
               //卸载钩子
               UnhookWindowsHookEx(hKeyboardHook);
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }




    }
} --------------------编程问答-------------------- 为什么没有人回答啊 --------------------编程问答-------------------- 你的附件里没东西。

补充：.NET技术 ,  C#