C# WINFORM 强制让窗体获得焦点(可实现单次置顶或持续置顶)

//首先要说明的是与TopMost的效果不同，TopMost是属性定义，而且设置True后，如果不设为Flase则一直置顶，效果很差，

//以下方法解决了TopMost使用上的不足

//调用API
[System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto, ExactSpelling = true)]
public static extern IntPtr GetForegroundWindow(); //获得本窗体的句柄
[System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SetForegroundWindow")]
public static extern bool SetForegroundWindow(IntPtr hWnd);//设置此窗体为活动窗体
//定义变量,句柄类型
public IntPtr Handle1;

//在窗体加载的时候给变量赋值,即将当前窗体的句柄赋给变量

void Form1_Load(object sender, EventArgs e)
{
Handle1 = this.Handle;
timer2.Enabled = true;
}

//加载一个定时器控件,验证当前WINDOWS句柄是否和本窗体的句柄一样,如果不一样,则激活本窗体

private void timer2_Tick(object sender, EventArgs e)
{
if (Handle1 != GetForegroundWindow()) //持续使该窗体置为最前,屏蔽该行则单次置顶
{
SetForegroundWindow(Handle1);

//timer2.Stop();//此处可以关掉定时器，则实现单次置顶
}
}

示例代码：

namespace WinFormsApp_GetForegroundWindowTest
{
    public partial class Form1 : Form
    {
        //调用API
        [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto, ExactSpelling = true)]
        public static extern IntPtr GetForegroundWindow(); //获得本窗体的句柄
        [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SetForegroundWindow")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);//设置此窗体为活动窗体
        //定义变量,句柄类型
        public IntPtr Handle1;
        Timer timer2 = new Timer();

        public Form1()
        {
            InitializeComponent();
        }

        Form Form2;

        //在窗体加载的时候给变量赋值,即将当前窗体的句柄赋给变量
        void Form1_Load(object sender, EventArgs e)
        {
            Handle1 = this.Handle;
            timer2.Tick += new EventHandler(timer2_Tick);
            timer2.Interval = 1000;
        }

        //加载一个定时器控件,验证当前WINDOWS句柄是否和本窗体的句柄一样,如果不一样,则激活本窗体
        private void timer2_Tick(object sender, EventArgs e)
        {
            //if (Handle1 != GetForegroundWindow()) //持续使该窗体置为最前,屏蔽该行则单次置顶
            //{
            SetForegroundWindow(Handle1);
            timer2.Stop();//此处可以关掉定时器，则实现单次置顶
            //}
        }

        private void btnSetForm2ToTop_Click(object sender, EventArgs e)
        {
            if (Form2 == null) return;

            timer2.Enabled = true;
            Handle1 = Form2.Handle;
        }

        private void btn_OpenForm2_Click(object sender, EventArgs e)
        {
            Form2 = new Form();
            Form2.Text = "Form2";
            Form2.Show();
        }
    }
}