C# winform 只运行一个应用程序

应用程序只有一个实例，当启动一次时创建实例，当多次启用时激活当前实例。

创建一个单利管理类

using Microsoft.VisualBasic.ApplicationServices;
public class AppContainer : WindowsFormsApplicationBase
{
public AppContainer()
{
IsSingleInstance = true;
EnableVisualStyles = true;
ShutdownStyle = ShutdownMode.AfterMainFormCloses;
}

protected override void OnCreateMainForm()
{
MainForm = new Form1();
}
}

在Program.cs中添加如下代码

static class Program
{
/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
AppContainer app = new AppContainer();
app.Run(Environment.GetCommandLineArgs());
}
}

第二版的实现：

using System.Threading;
using System.Runtime.InteropServices;
static class Program
{
#region 第二版
static Mutex mutex = new Mutex(true, "{FFAB7D56-89DB-4059-8465-4EB852326633}");
#endregion

/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
#region 第一版
//AppContainer app = new AppContainer();
//app.Run(Environment.GetCommandLineArgs());
#endregion

#region 第二版
if (mutex.WaitOne(TimeSpan.Zero, true))
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
else
{
NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST,NativeMethods.WM_SHOW, IntPtr.Zero,IntPtr.Zero);
}
#endregion
}
}
#region 第二版
internal class NativeMethods
{
public const int HWND_BROADCAST = 0xffff;
public static readonly int WM_SHOW = RegisterWindowMessage("WM_SHOWME");
[DllImport("user32")]
public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
[DllImport("user32")]
public static extern int RegisterWindowMessage(string message);
}
#endregion

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

#region 第二版
protected override void WndProc(ref Message m)
{
if (m.Msg == NativeMethods.WM_SHOW)
{
if (WindowState == FormWindowState.Minimized)
{
WindowState = FormWindowState.Normal;
}
bool top = TopMost;
TopMost = true;
TopMost = top;
}
base.WndProc(ref m);
}
#endregion
}

参考资料：https://www.codeproject.com/Articles/12890/Single-Instance-C-Application-for-NET-2-0
https://stackoverflow.com/questions/19147/what-is-the-correct-way-to-create-a-single-instance-application