目前流行的做法是使用winio模拟键盘硬件扫描码，但是winio并不稳定，时常有严重错误发生。使用keybd_event函数，这种方法非常简单，而且极为稳定。
一、keybd_event使用
详见：
https://www.cnblogs.com/xielong/p/6763121.html
//键盘事件
#region bVk参数 常量定义
public const byte vbKeyLButton = 0x1; // 鼠标左键
public const byte vbKeyRButton = 0x2; // 鼠标右键
public const byte vbKeyCancel = 0x3; // CANCEL 键
public const byte vbKeyMButton = 0x4; // 鼠标中键
public const byte vbKeyBack = 0x8; // BACKSPACE 键
public const byte vbKeyTab = 0x9; // TAB 键
public const byte vbKeyClear = 0xC; // CLEAR 键
public const byte vbKeyReturn = 0xD; // ENTER 键
public const byte vbKeyShift = 0x10; // SHIFT 键
public const byte vbKeyControl = 0x11; // CTRL 键
public const byte vbKeyAlt = 18; // Alt 键 (键码18)
public const byte vbKeyMenu = 0x12; // MENU 键
public const byte vbKeyPause = 0x13; // PAUSE 键
public const byte vbKeyCapital = 0x14; // CAPS LOCK 键
public const byte vbKeyEscape = 0x1B; // ESC 键
public const byte vbKeySpace = 0x20; // SPACEBAR 键
public const byte vbKeyPageUp = 0x21; // PAGE UP 键
public const byte vbKeyEnd = 0x23; // End 键
public const byte vbKeyHome = 0x24; // HOME 键
public const byte vbKeyLeft = 0x25; // LEFT ARROW 键
public const byte vbKeyUp = 0x26; // UP ARROW 键
public const byte vbKeyRight = 0x27; // RIGHT ARROW 键
public const byte vbKeyDown = 0x28; // DOWN ARROW 键
public const byte vbKeySelect = 0x29; // Select 键
public const byte vbKeyPrint = 0x2A; // PRINT SCREEN 键
public const byte vbKeyExecute = 0x2B; // EXECUTE 键
public const byte vbKeySnapshot = 0x2C; // SNAPSHOT 键
public const byte vbKeyDelete = 0x2E; // Delete 键
public const byte vbKeyHelp = 0x2F; // HELP 键
public const byte vbKeyNumlock = 0x90; // NUM LOCK 键
//常用键 字母键A到Z
public const byte vbKeyA = 65;
public const byte vbKeyB = 66;
public const byte vbKeyC = 67;
public const byte vbKeyD = 68;
public const byte vbKeyE = 69;
public const byte vbKeyF = 70;
public const byte vbKeyG = 71;
public const byte vbKeyH = 72;
public const byte vbKeyI = 73;
public const byte vbKeyJ = 74;
public const byte vbKeyK = 75;
public const byte vbKeyL = 76;
public const byte vbKeyM = 77;
public const byte vbKeyN = 78;
public const byte vbKeyO = 79;
public const byte vbKeyP = 80;
public const byte vbKeyQ = 81;
public const byte vbKeyR = 82;
public const byte vbKeyS = 83;
public const byte vbKeyT = 84;
public const byte vbKeyU = 85;
public const byte vbKeyV = 86;
public const byte vbKeyW = 87;
public const byte vbKeyX = 88;
public const byte vbKeyY = 89;
public const byte vbKeyZ = 90;
//数字键盘0到9
public const byte vbKey0 = 48; // 0 键
public const byte vbKey1 = 49; // 1 键
public const byte vbKey2 = 50; // 2 键
public const byte vbKey3 = 51; // 3 键
public const byte vbKey4 = 52; // 4 键
public const byte vbKey5 = 53; // 5 键
public const byte vbKey6 = 54; // 6 键
public const byte vbKey7 = 55; // 7 键
public const byte vbKey8 = 56; // 8 键
public const byte vbKey9 = 57; // 9 键
public const byte vbKeyNumpad0 = 0x60; //0 键
public const byte vbKeyNumpad1 = 0x61; //1 键
public const byte vbKeyNumpad2 = 0x62; //2 键
public const byte vbKeyNumpad3 = 0x63; //3 键
public const byte vbKeyNumpad4 = 0x64; //4 键
public const byte vbKeyNumpad5 = 0x65; //5 键
public const byte vbKeyNumpad6 = 0x66; //6 键
public const byte vbKeyNumpad7 = 0x67; //7 键
public const byte vbKeyNumpad8 = 0x68; //8 键
public const byte vbKeyNumpad9 = 0x69; //9 键
public const byte vbKeyMultiply = 0x6A; // MULTIPLICATIONSIGN(*)键
public const byte vbKeyAdd = 0x6B; // PLUS SIGN(+) 键
public const byte vbKeySeparator = 0x6C; // ENTER 键
public const byte vbKeySubtract = 0x6D; // MINUS SIGN(-) 键
public const byte vbKeyDecimal = 0x6E; // DECIMAL POINT(.) 键
public const byte vbKeyDivide = 0x6F; // DIVISION SIGN(/) 键
//F1到F12按键
public const byte vbKeyF1 = 0x70; //F1 键
public const byte vbKeyF2 = 0x71; //F2 键
public const byte vbKeyF3 = 0x72; //F3 键
public const byte vbKeyF4 = 0x73; //F4 键
public const byte vbKeyF5 = 0x74; //F5 键
public const byte vbKeyF6 = 0x75; //F6 键
public const byte vbKeyF7 = 0x76; //F7 键
public const byte vbKeyF8 = 0x77; //F8 键
public const byte vbKeyF9 = 0x78; //F9 键
public const byte vbKeyF10 = 0x79; //F10 键
public const byte vbKeyF11 = 0x7A; //F11 键
public const byte vbKeyF12 = 0x7B; //F12 键
#endregion
#region 引用win32api方法
///
/// 导入模拟键盘的方法
///
/// 按键的虚拟键值
/// 扫描码，一般不用设置，用0代替就行
/// 选项标志：0：表示按下，2：表示松开
/// 一般设置为0
[DllImport("user32.dll")]
public static extern void keybd_event(byte bVk, byte bScan, int dwFlags, int dwExtraInfo);
#endregion
调用：
//模拟按下A键
keybd_event(vbKeyA, 0, 0, 0);
//模拟松开A键
keybd_event(vbKeyA, 0, 2, 0);
二、mouse_event使用
详见：
http://blog.sina.com.cn/s/blog_71d894bd01013goa.html
//鼠标事件
private readonly int MOUSEEVENTF_LEFTDOWN = 0x0002;//模拟鼠标移动
private readonly int MOUSEEVENTF_MOVE = 0x0001;//模拟鼠标左键按下
private readonly int MOUSEEVENTF_LEFTUP = 0x0004;//模拟鼠标左键抬起
private readonly int MOUSEEVENTF_ABSOLUTE = 0x8000;//鼠标绝对位置
private readonly int MOUSEEVENTF_RIGHTDOWN = 0x0008; //模拟鼠标右键按下
private readonly int MOUSEEVENTF_RIGHTUP = 0x0010; //模拟鼠标右键抬起
private readonly int MOUSEEVENTF_MIDDLEDOWN = 0x0020; //模拟鼠标中键按下
private readonly int MOUSEEVENTF_MIDDLEUP = 0x0040;// 模拟鼠标中键抬起
[DllImport("user32")]
public static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);
//自定义鼠标移动事件
private void mouse_yd(int x, int y)
{
mouse_event(MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE, x * 65535 / 1600, y * 65535 / 900, 0, 0);//移动到需要点击的位置
}
//自定义鼠标左键单击
private void mouse_dj()
{
int x = Cursor.Position.X;
int y = Cursor.Position.Y;
mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_ABSOLUTE, x * 65535 / 1600, y * 65535 / 900, 0, 0);//点击
mouse_event(MOUSEEVENTF_LEFTUP | MOUSEEVENTF_ABSOLUTE, x * 65535 / 1600, y * 65535 / 900, 0, 0);//抬起
}