只能运行一个实例的方法 - 冷月孤峰

static void Main()
{
    bool initiallyOwned = true;
    bool isCreated;
    Mutex m = new Mutex(initiallyOwned,"MyTest",out isCreated);
    if (!(initiallyOwned && isCreated))
    {
        MessageBox.Show("已经有相同的实例在运行。","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);
        Application.Exit();
    }
    else
    {
        Application.Run(new MainForm());
    }

static void Main()

{

int ProceedingCount = 0;

Process[] ProceddingCon = Process.GetProcesses();

foreach(Process IsProcedding in ProceddingCon)

{

if(IsProcedding.ProcessName == Process.GetCurrentProcess().ProcessName)

{

ProceedingCount += 1;

}

if(ProceedingCount > 1)

{

MessageBox.Show("该系统已经在运行中。","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);

}

else

{

Application.EnableVisualStyles();

Application.DoEvents();

Application.Run(new MainForm());

}

private static bool CheckInstance()
        {
              string   procName   =   System.Diagnostics.Process.GetCurrentProcess().ProcessName;
              if((System.Diagnostics.Process.GetProcessesByName(procName)).GetUpperBound(0)   >0)
              {
                      return   true;
              }
              else
              {
                      return   false;
              }
        }

using System;
using System.Collections.Generic;
using System.Windows.Forms;

using System.Threading;

namespace PCBilling_Server
{
    static class Program
    {
        public static bool bOnlyOneInstance = false;
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            bOnlyOneInstance = false;
            Mutex mutex = new Mutex(true, Application.UserAppDataPath.Replace(@"\", "_"), out bOnlyOneInstance);

            if (!bOnlyOneInstance)
            {
                MessageBox.Show("系统已经运行!", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);
                System.Environment.Exit(0);
                return;
            }

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Frm_Login());
        }
    }
}

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Diagnostics;

using System.Reflection;

using System.Runtime.InteropServices;

public class MainForm : System.Windows.Forms.Form

{

private const int WS_SHOWNORMAL = 1;

[DllImport("User32.dll")]

private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

[DllImport("User32.dll")]

private static extern bool SetForegroundWindow(IntPtr hWnd);

public MainForm()

{

InitializeComponent();

}

/// <summary>

/// 应用程序的主入口点。

/// </summary>

[STAThread]

static void Main()

{

Process instance = GetRunningInstance();

if(instance == null)

{

Application.Run(new MainForm());

}

else

{

HandleRunningInstance(instance);

}

/// <summary>

/// 获取应用程序的实例,没有其它的例程，返回Null

/// </summary>

/// <returns></returns>

public static Process GetRunningInstance()

{

Process current = Process.GetCurrentProcess();

Process[] processes = Process.GetProcessesByName (current.ProcessName);

//遍历正在有相同名字运行的例程

foreach (Process process in processes)

{

//忽略现有的例程

if (process.Id != current.Id)

//确保例程从EXE文件运行

if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)

//返回另一个例程实例

return process;

}

return null;

}

/// <summary>

/// 获取窗口句柄

/// </summary>

/// <param name="instance"></param>

public static void HandleRunningInstance(Process instance)

{

//确保窗口没有被最小化或最大化

ShowWindowAsync (instance.MainWindowHandle , WS_SHOWNORMAL);

//设置真实例程为foreground window

SetForegroundWindow (instance.MainWindowHandle);

}

#region 不重复打开MDI子窗体
        /// <summary>
        /// 不重复打开MDI子窗体
        /// 调用：this.OpenMDIWindow(typeof(窗体名).ToString());
        /// </summary>
        /// <param name="ChildTypeString">窗体名称(typeof(FormName).ToString())</param>
        private void OpenMDIWindow(string ChildTypeString)
        {
            Form myChild = null;
            if (!ContainMDIChild(ChildTypeString))
            {
                // Get current process assembly
                Assembly assembly = Assembly.GetExecutingAssembly();
                // Create data type using type string
                Type typForm = assembly.GetType(ChildTypeString);
                // Create object using type's "InvokeMember" method
                Object obj = typForm.InvokeMember(
                    null,
                    BindingFlags.DeclaredOnly |
                    BindingFlags.Public | BindingFlags.NonPublic |
                    BindingFlags.Instance | BindingFlags.CreateInstance,
                    null,
                    null,
                    null);
                // Show child form
                if (obj != null)
                {
                    this.Refresh();
                    //Form frmTip = LoadTip.ShowTipForm(this, "正在加载窗体");

                    myChild = obj as Form;
                    myChild.MdiParent = this;
                    myChild.WindowState = FormWindowState.Maximized;
                    myChild.Show();
                    myChild.Focus();

                    //frmTip.Close();

                }
            }
        }

        /// <summary>
        /// Search mdi child form by specific type string
        /// </summary>
        /// <param name="ChildTypeString"></param>
        /// <returns></returns>
        private bool ContainMDIChild(string ChildTypeString)
        {
            Form myMDIChild = null;
            foreach (Form f in this.MdiChildren)
            {
                if (f.GetType().ToString() == ChildTypeString)
                {
                    // found it
                    myMDIChild = f;
                    break;
                }
            }
            // Show the exist form
            if (myMDIChild != null)
            {
                myMDIChild.TopMost = true;
                myMDIChild.Show();
                myMDIChild.Focus();
                return true;
            }
            else
            {
                return false;
            }
        }
        #endregion