步骤

UI Automation 只适用于，标准的win32和 WPF程序
需要添加对UIAutomationClient、 UIAutomationProvider、 UIAutomationTypes的引用
代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Automation;
using System.Windows.Forms;
using System.Windows.Input;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private Process processnotepad;
        private Process processcalc;

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //打开笔记本
            processnotepad = Process.Start(@"C:\Windows\System32\notepad.exe");
        }

        private void button2_Click(object sender, EventArgs e)
        {
            //关闭笔记本
            processnotepad.Kill();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            //AutomationElement表示 UI 自动化树中的一个 UI 自动化元素，并包含由 UI 自动化客户端应用程序用作标识符的值。
            //获取当前桌面的根 AutomationElement。
            AutomationElement desktop = AutomationElement.RootElement;
            //StringBuilder不在内存中创建新对象，而是动态扩展内存以容纳修改后的字符串。
            StringBuilder sb = new StringBuilder();
            //TreeScope(枚举)包含指定 UI 自动化目录树内元素的范围的值。具体参考请点击以下链接进行查看
            //TreeScope官方链接：https://learn.microsoft.com/zh-cn/dotnet/api/system.windows.automation.treescope?view=windowsdesktop-7.0
            AutomationElementCollection topWindows = desktop.FindAll(TreeScope.Children, new PropertyCondition(AutomationElement.ClassNameProperty, "ApplicationFrameWindow"));//查找计算器
            for (int i = 0; i < topWindows.Count; i++)
            {
                AutomationElement topWindow = topWindows[i];
                sb.AppendLine("Name:" + topWindow.Current.Name + ";ClassName=" + topWindow.Current.ClassName);
            }
            MessageBox.Show(sb.ToString());
        }

        private void button4_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children, new PropertyCondition(AutomationElement.ClassNameProperty, "ApplicationFrameWindow"));
            AutomationElementCollection btn2 = calcFrame1.FindAll(TreeScope.Descendants, new PropertyCondition(AutomationElement.AutomationIdProperty, "num9Button"));
            AutomationElement btn = btn2[0];
            MessageBox.Show(btn.Current.Name);
        }

        private void button5_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "ApplicationFrameWindow"));

            Condition conditionBtn6 = new AndCondition(
                new PropertyCondition(AutomationElement.ClassNameProperty, "Button"),
                new PropertyCondition(AutomationElement.NameProperty, "六")
                );
            var btn6 = calcFrame1.FindFirst(TreeScope.Descendants, conditionBtn6);
            //InvokePattern 表示用于启动或执行单个明确操作的控件，并且这些控件在激活时不保持其状态。
            //InvokePattern.Pattern 标识 InvokePattern 控件模式。
            //InvokePattern官方链接 https://learn.microsoft.com/zh-cn/dotnet/api/system.windows.automation.invokepattern?view=windowsdesktop-7.0
            InvokePattern button6Invoke = (InvokePattern)btn6.GetCurrentPattern(InvokePattern.Pattern);
            //Invoke() 发送请求以激活控件并启动其单一、明确的操作。
            button6Invoke.Invoke();

            

            Condition conditionBtnPlus = new AndCondition(
           new PropertyCondition(AutomationElement.ClassNameProperty, "Button"),
           new PropertyCondition(AutomationElement.NameProperty, "加")
           );
            var btnPlus = calcFrame1.FindFirst(TreeScope.Descendants, conditionBtnPlus);
            InvokePattern buttonPlusInvoke = (InvokePattern)btnPlus.GetCurrentPattern(InvokePattern.Pattern);
            buttonPlusInvoke.Invoke();
        }
        private static void InvokeButton(AutomationElement e)
        {
            InvokePattern Invoke = (InvokePattern)e.GetCurrentPattern(InvokePattern.Pattern);
            Invoke.Invoke();
        }
        private static void ClickCalculatorButton(AutomationElement calcFrame1, String name)
        {
            Condition conditionBtn = new AndCondition(
               new PropertyCondition(AutomationElement.ClassNameProperty, "Button"),
               new PropertyCondition(AutomationElement.NameProperty, name)
               );
            var btn = calcFrame1.FindFirst(TreeScope.Descendants, conditionBtn);
            // MessageBox.Show(btn.Current.Name);
            if (btn == null)
            {
                throw new Exception("找不到此" + name + "的按钮");
            }
            InvokeButton(btn);
        }

        private void button6_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "ApplicationFrameWindow"));
            ClickCalculatorButton(calcFrame1, "三");
            ClickCalculatorButton(calcFrame1, "乘以");
            ClickCalculatorButton(calcFrame1, "五");
            ClickCalculatorButton(calcFrame1, "五");
            ClickCalculatorButton(calcFrame1, "等于");
        }

        [DllImport("user32.dll")]
        public static extern void SetCursorPos(int x, int y);

        [DllImport("user32.dll")]
        public static extern void mouse_event(int dwFlags, int dx, int dy, int cButtons, int dwExtraInfo);


        private void button7_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "ApplicationFrameWindow"));

            Condition conditionBtn6 = new AndCondition(
                new PropertyCondition(AutomationElement.ClassNameProperty, "Button"),
                new PropertyCondition(AutomationElement.NameProperty, "六")
                );
            var btn6 = calcFrame1.FindFirst(TreeScope.Descendants, conditionBtn6);

            SetCursorPos((int)btn6.GetClickablePoint().X, (int)btn6.GetClickablePoint().Y);
            //mouse_event(0x0002 | 0x0004, 0, 0, 0, 0);
            mouse_event(0x0002, 0, 0, 0, 0);  // 模拟鼠标左键按下
            mouse_event(0x0004, 0, 0, 0, 0);  // 模拟鼠标左键弹起

        }



        private void button8_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));

            Condition conditionEdit = new AndCondition( 
                new PropertyCondition(AutomationElement.ClassNameProperty, "Edit"), new PropertyCondition(AutomationElement.NameProperty, "文本编辑器"));
            AutomationElement txtEdit = calcFrame1.FindFirst(TreeScope.Descendants, conditionEdit);
            txtEdit.SetFocus();
            SendKeys.Send("追加123456789");
        }

        private const int WM_SETTEXT = 0x000C;

        [DllImport("user32.dll")]
        private static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("User32.dll")]
        private static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindows);

        [DllImport("User32.dll")]
        private static extern Int32 SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, StringBuilder lParam);

        private void button9_Click(object sender, EventArgs e)
        {
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));

            Condition conditionEdit = new AndCondition(
                new PropertyCondition(AutomationElement.ClassNameProperty, "Edit"), new PropertyCondition(AutomationElement.NameProperty, "文本编辑器"));
            AutomationElement txtEdit = calcFrame1.FindFirst(TreeScope.Descendants, conditionEdit);
            //.NET提供了一个结构体System.IntPtr专门用来代表句柄或指针。
            //句柄是对象的标识符，当调用这些API创建对象时，它们并不直接返回指向对象的指针，
            //而是会返回一个32位或64位的整数值，这个在进程或系统范围内唯一的整数值就是句柄（Handle）,
            //随后程序再次访问对象，或者删除对象，都将句柄作为Windows API的参数来间接对这些对象进行操作。
            //句柄是一个结构体，简单的来说，它是指针的一个封装，是C#中指针的替代者
            //句柄链接：https://blog.csdn.net/sinat_40003796/article/details/127244155
            IntPtr hWnd = FindWindow("Notepad", null);
            if (!hWnd.Equals(IntPtr.Zero))
            {
                IntPtr edithWnd = FindWindowEx(hWnd, IntPtr.Zero, "Edit", null);
                if (!edithWnd.Equals(IntPtr.Zero))
                {
                    SendMessage(edithWnd, WM_SETTEXT, IntPtr.Zero, new StringBuilder("重写123456789"));
                }
            }
            else
            {
            }

        }

        private void button10_Click(object sender, EventArgs e)
        {
            //点击后有列表的按钮不要当成点击事件
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));
            Condition myCondition2 = new PropertyCondition(AutomationElement.NameProperty, "编辑(E)");
            AutomationElement w2 = calcFrame1.FindFirst(TreeScope.Descendants, myCondition2);
            ExpandCollapsePattern ecp = (ExpandCollapsePattern)w2.GetCurrentPattern(ExpandCollapsePattern.Pattern);
            ecp.Expand();
        }

        private AutomationElement autoElementGet1(AutomationElement e, string s)
        {
            Condition myCondition1 = new PropertyCondition(AutomationElement.AutomationIdProperty, s);
            Condition myCondition2 = new PropertyCondition(AutomationElement.NameProperty, s);
            Condition myCondition3 = new PropertyCondition(AutomationElement.AcceleratorKeyProperty, s);
            Condition myCondition4 = new PropertyCondition(AutomationElement.ClassNameProperty, s);
            Condition myCondition5 = new PropertyCondition(AutomationElement.AccessKeyProperty, s);
            Condition myCondition6 = new PropertyCondition(AutomationElement.LocalizedControlTypeProperty, s);
            Condition myCondition = new OrCondition(myCondition1, myCondition2, myCondition3, myCondition4, myCondition5,
                myCondition6);
            AutomationElementCollection myCollection = e.FindAll(TreeScope.Descendants, myCondition);
            return myCollection[0];
        }
        private void button11_Click(object sender, EventArgs e)
        {
            //随机元素获取
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));
            AutomationElement filename = autoElementGet1(calcFrame1, "文件(F)");
            MessageBox.Show("Name:" + filename.Current.Name + ";ClassName=" + filename.Current.ClassName);
        }

        private void button12_Click(object sender, EventArgs e)
        {
            //遍历子控件
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));
            Condition myCondition1 = new PropertyCondition(AutomationElement.AutomationIdProperty, "MenuBar");
            AutomationElement MenuBar = calcFrame1.FindFirst(TreeScope.Descendants, myCondition1);
            AutomationElementCollection MenuBarChildAll = MenuBar.FindAll(TreeScope.Children, Condition.TrueCondition);
            for (int i = 0; i < MenuBarChildAll.Count; i++)
            {
                AutomationElement MenuBarChild = MenuBarChildAll[i];
                MessageBox.Show("Name:" + MenuBarChild.Current.Name + ";ClassName=" + MenuBarChild.Current.ClassName + ";ControlType=" + MenuBarChild.Current.ControlType);
            }


        }

        private void button13_Click(object sender, EventArgs e)
        {
            processcalc = Process.Start(@"C:\Windows\System32\calc.exe");
        }

        private void button14_Click(object sender, EventArgs e)
        {
            processcalc.Kill();
        }

        private void button15_Click(object sender, EventArgs e)
        {
            //点击后有列表的按钮不要当成点击事件
            AutomationElement desktop = AutomationElement.RootElement;
            var calcFrame1 = desktop.FindFirst(TreeScope.Children,
                new PropertyCondition(AutomationElement.ClassNameProperty, "Notepad"));
            Condition myCondition1 = new PropertyCondition(AutomationElement.NameProperty, "文件(F)");
            AutomationElement w1 = calcFrame1.FindFirst(TreeScope.Descendants, myCondition1);
            ExpandCollapsePattern ecp = (ExpandCollapsePattern)w1.GetCurrentPattern(ExpandCollapsePattern.Pattern);
            ecp.Expand();
            Condition myCondition2 = new PropertyCondition(AutomationElement.NameProperty, "退出(X)");
            AutomationElementCollection myCollection = w1.FindAll(TreeScope.Descendants, myCondition2);
            AutomationElement w2 = myCollection[0];
            InvokePattern ipn = (InvokePattern)w2.GetCurrentPattern(InvokePattern.Pattern);
            ipn.Invoke();
            Thread.Sleep(500);
            AutomationElement savefile = calcFrame1.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.NameProperty, "保存(S)"));
            if (savefile != null)
            {
                InvokePattern savefilebutton = (InvokePattern)savefile.GetCurrentPattern(InvokePattern.Pattern);
                savefilebutton.Invoke();
                Thread.Sleep(500);
                AutomationElement Saveasform = calcFrame1.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.NameProperty, "另存为"));
                AutomationElement edit1 = Saveasform.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.AutomationIdProperty, "1001"));
                ValuePattern vp = (ValuePattern)edit1.GetCurrentPattern(ValuePattern.Pattern);
                vp.SetValue("aaa.txt");
                AutomationElement savefilepath = Saveasform.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.NameProperty, "保存(S)"));
                InvokePattern savefilepathbutton = (InvokePattern)savefilepath.GetCurrentPattern(InvokePattern.Pattern);
                savefilepathbutton.Invoke();
                Thread.Sleep(500);
                AutomationElement yesSaveasform = Saveasform.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.NameProperty, "确认另存为"));
                AutomationElement issavefilepath = Saveasform.FindFirst(TreeScope.Descendants, new PropertyCondition(AutomationElement.NameProperty, "是(Y)"));
                if (issavefilepath != null) {
                    InvokePattern issavefilepathbutton = (InvokePattern)issavefilepath.GetCurrentPattern(InvokePattern.Pattern);
                    issavefilepathbutton.Invoke();
                }
            }
            

        }
    }
}