一个程序通过窗体句柄控制另一个窗体

接下来，我们来演示不同程序中，怎么通过窗体句柄控制其它程序窗体。

演示的例子是：控制系统的记事本窗体，先移动，再最大化，最后关闭

要求：桌面上有一个记事本，名称是：测试文本.txt - 记事本，保证是打开的

界面只有一个按钮，btnCloseText

引用的windowapi函数dll如下：

        /// <summary>
        /// 获取窗体的句柄函数
        /// </summary>
        /// <param name="lpClassName">窗口类名</param>
        /// <param name="lpWindowName">窗口标题名</param>
        /// <returns>返回句柄</returns>
        [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        /// <summary>
        /// 移动窗体的函数
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <param name="x">窗体新位置x轴坐标</param>
        /// <param name="y">窗体新位置y轴坐标</param>
        /// <param name="nWidth">窗体新位置宽度</param>
        /// <param name="nHeight">窗体新位置高度</param>
        /// <param name="BRePaint">是否刷新窗体</param>
        /// <returns></returns>
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int MoveWindow(IntPtr hWnd, int x, int y, int nWidth, int nHeight, bool BRePaint);

        /// <summary>
        /// 通过句柄，窗体显示函数
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <param name="cmdShow">显示方式</param>
        /// <returns>返工成功与否</returns>
        [DllImport("user32.dll", EntryPoint = "ShowWindowAsync", SetLastError = true)]
        public static extern bool ShowWindow(IntPtr hWnd, int cmdShow);

        /// <summary>
        /// 发送消息到窗体函数
        /// </summary>
        /// <param name="hwnd">窗体句柄</param>
        /// <param name="wMsg">消息类型</param>
        /// <param name="wParam">附带消息</param>
        /// <param name="lParam"></param>
        /// <returns></returns>
        [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern IntPtr SendMessage(IntPtr hwnd, uint wMsg, int wParam, int lParam);

实现代码：

        //wMsg类型，关闭窗体
        private const int WM_CLOSE = 0x10;

        private void btnCloseText_Click(object sender, EventArgs e)
        {
            IntPtr textHandle = FindWindow(null, "测试文本.txt - 记事本");
            if (textHandle != IntPtr.Zero)
            {
                //移动记事本窗体
                MoveWindow(textHandle, 0, 100, 800, 600, true);
                //延时3秒后
                Thread.Sleep(3000);
                //设置窗体最大化显示
                ShowWindow(textHandle, 3);
                //延时3秒后
                Thread.Sleep(3000);
                //向记事本程序窗体发送关闭信息
                SendMessage(textHandle, WM_CLOSE,0,0);
            }
        }

整体代码：

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

namespace WindowsForms
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 获取窗体的句柄函数
        /// </summary>
        /// <param name="lpClassName">窗口类名</param>
        /// <param name="lpWindowName">窗口标题名</param>
        /// <returns>返回句柄</returns>
        [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        /// <summary>
        /// 移动窗体的函数
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <param name="x">窗体新位置x轴坐标</param>
        /// <param name="y">窗体新位置y轴坐标</param>
        /// <param name="nWidth">窗体新位置宽度</param>
        /// <param name="nHeight">窗体新位置高度</param>
        /// <param name="BRePaint">是否刷新窗体</param>
        /// <returns></returns>
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int MoveWindow(IntPtr hWnd, int x, int y, int nWidth, int nHeight, bool BRePaint);

        /// <summary>
        /// 通过句柄，窗体显示函数
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <param name="cmdShow">显示方式</param>
        /// <returns>返工成功与否</returns>
        [DllImport("user32.dll", EntryPoint = "ShowWindowAsync", SetLastError = true)]
        public static extern bool ShowWindow(IntPtr hWnd, int cmdShow);

        /// <summary>
        /// 发送消息到窗体函数
        /// </summary>
        /// <param name="hwnd">窗体句柄</param>
        /// <param name="wMsg">消息类型</param>
        /// <param name="wParam">附带消息</param>
        /// <param name="lParam"></param>
        /// <returns></returns>
        [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern IntPtr SendMessage(IntPtr hwnd, uint wMsg, int wParam, int lParam);

        //wMsg类型，关闭窗体
        private const int WM_CLOSE = 0x10;

        private void btnCloseText_Click(object sender, EventArgs e)
        {
            IntPtr textHandle = FindWindow(null, "测试文本.txt - 记事本");
            if (textHandle != IntPtr.Zero)
            {
                //移动记事本窗体
                MoveWindow(textHandle, 0, 100, 800, 600, true);
                //延时3秒后
                Thread.Sleep(3000);
                //设置窗体最大化显示
                ShowWindow(textHandle, 3);
                //延时3秒后
                Thread.Sleep(3000);
                //向记事本程序窗体发送关闭信息
                SendMessage(textHandle, WM_CLOSE,0,0);
            }
        }
    }
}

演示结果如下：

1）刚开始运行结果（图片太大，不截图）

2）窗体移动后结果（图片太大，不截图）

3）最大化窗体结果（图片太大，不截图）

4）关闭记事本结果（图片太大，不截图）