模拟键盘录入，复制粘贴剪切，全选

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

namespace KeyBoardInput
{
    class KeyBoard
    {
        [DllImport("user32.dll")]
        private static extern void keybd_event(
            byte bVk, byte bScan, uint dwFlags, int dwExtraInfo);

        private static Dictionary<string, byte> keycodedic;

        const int KEYEVENTF_KEYUP = 0x0002;
        public static bool Input(string str)
        {
            #region init dic
            if (keycodedic == null)
            {
                keycodedic = new Dictionary<string, byte>();
                keycodedic.Add("A", 0x41);
                keycodedic.Add("B", 0x42);
                keycodedic.Add("C", 0x43);
                keycodedic.Add("D", 0x44);
                keycodedic.Add("E", 0x45);
                keycodedic.Add("F", 70);
                keycodedic.Add("G", 0x47);
                keycodedic.Add("H", 0x48);
                keycodedic.Add("I", 0x49);
                keycodedic.Add("J", 0x4a);
                keycodedic.Add("K", 0x4b);
                keycodedic.Add("L", 0x4c);
                keycodedic.Add("M", 0x4d);
                keycodedic.Add("N", 0x4e);
                keycodedic.Add("O", 0x4f);
                keycodedic.Add("P", 80);
                keycodedic.Add("Q", 0x51);
                keycodedic.Add("R", 0x52);
                keycodedic.Add("S", 0x53);
                keycodedic.Add("T", 0x54);
                keycodedic.Add("U", 0x55);
                keycodedic.Add("V", 0x56);
                keycodedic.Add("W", 0x57);
                keycodedic.Add("X", 0x58);
                keycodedic.Add("Y", 0x59);
                keycodedic.Add("Z", 90);
                keycodedic.Add("0", 0x30);
                keycodedic.Add("1", 0x31);
                keycodedic.Add("2", 50);
                keycodedic.Add("3", 0x33);
                keycodedic.Add("4", 0x34);
                keycodedic.Add("5", 0x35);
                keycodedic.Add("6", 0x36);
                keycodedic.Add("7", 0x37);
                keycodedic.Add("8", 0x38);
                keycodedic.Add("9", 0x39);
                keycodedic.Add(".", 110);
                keycodedic.Add("LEFT", 0x25);
                keycodedic.Add("UP", 0x26);
                keycodedic.Add("RIGHT", 0x27);
                keycodedic.Add("DOWN", 40);
                keycodedic.Add("-", 0x6d);
            }
            #endregion
            foreach (char ch in str.ToUpper())
            {
                //模拟单击键，可规避连续输入键值时遗漏或延长Thread.Sleep(50);
                keybd_event(0x1, 0, 1, 0);
                keybd_event(keycodedic[ch.ToString()], 0, 1, 0);
            }
            return false;
        }

        public static void Move(int count, string direction)
        {
            for (int i = 0; i < count; i++)
            {
                keybd_event(keycodedic[direction], 0, 0, 0);
                Thread.Sleep(100);
            }
            if (count == 1)
            {
                Thread.Sleep(0x3e8);
            }
        }

        public static void Enter()
        {
            keybd_event(0xD, 0, 0, 0);
            Thread.Sleep(50);
            keybd_event(0xD, 0, KEYEVENTF_KEYUP, 0);
        }

        public static void Shift()
        {
            keybd_event(0x10, 0, 0, 0);
            Thread.Sleep(50);
            keybd_event(0x10, 0, KEYEVENTF_KEYUP, 0);
        }

        public static void Capslock()
        {
            keybd_event(0x14, 0, 0, 0);
            Thread.Sleep(50);
            keybd_event(0x14, 0, KEYEVENTF_KEYUP, 0);
        }

        public static void CtrlV()
        {
            keybd_event(0x11, 0, 0, 0);
            keybd_event(0x56, 0, 0, 0);
            keybd_event(0x56, 0, KEYEVENTF_KEYUP, 0);
            keybd_event(0x11, 0, KEYEVENTF_KEYUP, 0);
        }

        public static void CtrlC()
        {
            keybd_event(0x11, 0, 0, 0);
            keybd_event(0x43, 0, 0, 0);
            keybd_event(0x43, 0, KEYEVENTF_KEYUP, 0);
            keybd_event(0x11, 0, KEYEVENTF_KEYUP, 0);
        }
        public static void CtrlA()
        {
            keybd_event(0x11, 0, 0, 0);
            keybd_event(0x41, 0, 0, 0);
            keybd_event(0x41, 0, KEYEVENTF_KEYUP, 0);
            keybd_event(0x11, 0, KEYEVENTF_KEYUP, 0);
        }
        public static void CtrlX()
        {
            keybd_event(0x11, 0, 0, 0);
            keybd_event(0x58, 0, 0, 0);
            keybd_event(0x58, 0, KEYEVENTF_KEYUP, 0);
            keybd_event(0x11, 0, KEYEVENTF_KEYUP, 0);
        }
    }
}

模拟输入：

private void button1_Click(object sender, EventArgs e)
        {
            this.textBox1.Focus();
            KeyBoard.Input("abcde");
            KeyBoard.Enter();
            KeyBoard.Input("123456");
            KeyBoard.Enter();
        }

复制粘贴剪切：

private void button2_Click(object sender, EventArgs e)
        {
            this.textBox1.Focus();
            KeyBoard.CtrlV();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            this.textBox1.Focus();
            KeyBoard.CtrlX();
        }

        private void button5_Click(object sender, EventArgs e)
        {
            this.textBox1.Focus();
            KeyBoard.CtrlA();
        }

        private void button4_Click(object sender, EventArgs e)
        {
            this.textBox1.Focus();
            KeyBoard.CtrlC();
        }

全选，先定义事件:

//添加从键盘按ctrl+a全选事件
        private void textBox1_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.Modifiers == Keys.Control && e.KeyCode == Keys.A)
            {
                ((TextBox)sender).SelectAll();
                this.textBox1.Focus();
            }
        }
        //添加双击textbox全选事件
        private void textBox1_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            textBox1.Select(0, textBox1.Text.Length);
        }