在。net下使用c#和WPF(而不是Windows窗体或控制台)，创建一个只能作为单个实例运行的应用程序的正确方法是什么?
我知道它与某种叫做互斥的神秘事物有关，我很少能找到有人费心停下来解释其中一个是什么。
代码还需要通知已经运行的实例，用户试图启动第二个实例，如果存在命令行参数，还可能传递任何命令行参数。
当前回答
更新2017-01-25。在尝试了一些东西之后，我决定使用VisualBasic.dll，它更容易，工作效果更好(至少对我来说)。我让我之前的答案只是作为参考…
只是作为参考，这是我如何不传递参数(我找不到任何理由这样做…我指的是带有参数的单个应用程序，这些参数可以从一个实例传递到另一个实例)。 如果需要文件关联，那么应用程序应该(根据用户的标准期望)为每个文档实例化。如果你必须传递args到现有的应用程序，我想我会使用vb dll。
不传递参数(只是单实例应用程序)，我更喜欢不注册一个新的窗口消息，不覆盖Matt Davis解决方案中定义的消息循环。虽然添加一个VisualBasic dll不是一个大问题，但我不喜欢添加一个新的引用只是做单个实例应用程序。此外，我更喜欢用Main实例化一个新类，而不是调用Shutdown from app. startup重写以确保尽快退出。
希望大家都喜欢……或者会启发一点:-)
项目启动类应该设置为“SingleInstanceApp”。
public class SingleInstanceApp
{
[STAThread]
public static void Main(string[] args)
{
Mutex _mutexSingleInstance = new Mutex(true, "MonitorMeSingleInstance");
if (_mutexSingleInstance.WaitOne(TimeSpan.Zero, true))
{
try
{
var app = new App();
app.InitializeComponent();
app.Run();
}
finally
{
_mutexSingleInstance.ReleaseMutex();
_mutexSingleInstance.Close();
}
}
else
{
MessageBox.Show("One instance is already running.");
var processes = Process.GetProcessesByName(Assembly.GetEntryAssembly().GetName().Name);
{
if (processes.Length > 1)
{
foreach (var process in processes)
{
if (process.Id != Process.GetCurrentProcess().Id)
{
WindowHelper.SetForegroundWindow(process.MainWindowHandle);
}
}
}
}
}
}
}
WindowHelper:
using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Threading;
namespace HQ.Util.Unmanaged
{
public class WindowHelper
{
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SetForegroundWindow(IntPtr hWnd);
其他回答
更新2017-01-25。在尝试了一些东西之后，我决定使用VisualBasic.dll，它更容易，工作效果更好(至少对我来说)。我让我之前的答案只是作为参考…
只是作为参考，这是我如何不传递参数(我找不到任何理由这样做…我指的是带有参数的单个应用程序，这些参数可以从一个实例传递到另一个实例)。 如果需要文件关联，那么应用程序应该(根据用户的标准期望)为每个文档实例化。如果你必须传递args到现有的应用程序，我想我会使用vb dll。
不传递参数(只是单实例应用程序)，我更喜欢不注册一个新的窗口消息，不覆盖Matt Davis解决方案中定义的消息循环。虽然添加一个VisualBasic dll不是一个大问题，但我不喜欢添加一个新的引用只是做单个实例应用程序。此外，我更喜欢用Main实例化一个新类，而不是调用Shutdown from app. startup重写以确保尽快退出。
希望大家都喜欢……或者会启发一点:-)
项目启动类应该设置为“SingleInstanceApp”。
public class SingleInstanceApp
{
[STAThread]
public static void Main(string[] args)
{
Mutex _mutexSingleInstance = new Mutex(true, "MonitorMeSingleInstance");
if (_mutexSingleInstance.WaitOne(TimeSpan.Zero, true))
{
try
{
var app = new App();
app.InitializeComponent();
app.Run();
}
finally
{
_mutexSingleInstance.ReleaseMutex();
_mutexSingleInstance.Close();
}
}
else
{
MessageBox.Show("One instance is already running.");
var processes = Process.GetProcessesByName(Assembly.GetEntryAssembly().GetName().Name);
{
if (processes.Length > 1)
{
foreach (var process in processes)
{
if (process.Id != Process.GetCurrentProcess().Id)
{
WindowHelper.SetForegroundWindow(process.MainWindowHandle);
}
}
}
}
}
}
}
WindowHelper:
using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Threading;
namespace HQ.Util.Unmanaged
{
public class WindowHelper
{
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SetForegroundWindow(IntPtr hWnd);
代码c# . net单实例应用程序作为标记答案的参考是一个很好的开始。
然而，我发现它不能很好地处理已经存在的实例打开了一个模态对话框的情况，无论该对话框是托管的(像另一个表单，如about框)，还是非托管的(像OpenFileDialog，甚至在使用标准的. net类时)。使用原始代码，主表单被激活，但模态表单保持不激活状态，这看起来很奇怪，而且用户必须点击它才能继续使用应用程序。
因此，我已经创建了一个SingleInstance实用程序类来为Winforms和WPF应用程序自动处理所有这些。
Winforms:
1)像这样修改Program类:
static class Program
{
public static readonly SingleInstance Singleton = new SingleInstance(typeof(Program).FullName);
[STAThread]
static void Main(string[] args)
{
// NOTE: if this always return false, close & restart Visual Studio
// this is probably due to the vshost.exe thing
Singleton.RunFirstInstance(() =>
{
SingleInstanceMain(args);
});
}
public static void SingleInstanceMain(string[] args)
{
// standard code that was in Main now goes here
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
2)像这样修改主窗口类:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
protected override void WndProc(ref Message m)
{
// if needed, the singleton will restore this window
Program.Singleton.OnWndProc(this, m, true);
// TODO: handle specific messages here if needed
base.WndProc(ref m);
}
}
WPF:
1)像这样修改App页面(并确保你将其构建动作设置为page，以便能够重新定义Main方法):
public partial class App : Application
{
public static readonly SingleInstance Singleton = new SingleInstance(typeof(App).FullName);
[STAThread]
public static void Main(string[] args)
{
// NOTE: if this always return false, close & restart Visual Studio
// this is probably due to the vshost.exe thing
Singleton.RunFirstInstance(() =>
{
SingleInstanceMain(args);
});
}
public static void SingleInstanceMain(string[] args)
{
// standard code that was in Main now goes here
App app = new App();
app.InitializeComponent();
app.Run();
}
}
2)像这样修改主窗口类:
public partial class MainWindow : Window
{
private HwndSource _source;
public MainWindow()
{
InitializeComponent();
}
protected override void OnSourceInitialized(EventArgs e)
{
base.OnSourceInitialized(e);
_source = (HwndSource)PresentationSource.FromVisual(this);
_source.AddHook(HwndSourceHook);
}
protected virtual IntPtr HwndSourceHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
// if needed, the singleton will restore this window
App.Singleton.OnWndProc(hwnd, msg, wParam, lParam, true, true);
// TODO: handle other specific message
return IntPtr.Zero;
}
这里是实用程序类:
using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Threading;
namespace SingleInstanceUtilities
{
public sealed class SingleInstance
{
private const int HWND_BROADCAST = 0xFFFF;
[DllImport("user32.dll")]
private static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
[DllImport("user32.dll", CharSet = CharSet.Unicode)]
private static extern int RegisterWindowMessage(string message);
[DllImport("user32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);
public SingleInstance(string uniqueName)
{
if (uniqueName == null)
throw new ArgumentNullException("uniqueName");
Mutex = new Mutex(true, uniqueName);
Message = RegisterWindowMessage("WM_" + uniqueName);
}
public Mutex Mutex { get; private set; }
public int Message { get; private set; }
public void RunFirstInstance(Action action)
{
RunFirstInstance(action, IntPtr.Zero, IntPtr.Zero);
}
// NOTE: if this always return false, close & restart Visual Studio
// this is probably due to the vshost.exe thing
public void RunFirstInstance(Action action, IntPtr wParam, IntPtr lParam)
{
if (action == null)
throw new ArgumentNullException("action");
if (WaitForMutext(wParam, lParam))
{
try
{
action();
}
finally
{
ReleaseMutex();
}
}
}
public static void ActivateWindow(IntPtr hwnd)
{
if (hwnd == IntPtr.Zero)
return;
FormUtilities.ActivateWindow(FormUtilities.GetModalWindow(hwnd));
}
public void OnWndProc(IntPtr hwnd, int m, IntPtr wParam, IntPtr lParam, bool restorePlacement, bool activate)
{
if (m == Message)
{
if (restorePlacement)
{
WindowPlacement placement = WindowPlacement.GetPlacement(hwnd, false);
if (placement.IsValid && placement.IsMinimized)
{
const int SW_SHOWNORMAL = 1;
placement.ShowCmd = SW_SHOWNORMAL;
placement.SetPlacement(hwnd);
}
}
if (activate)
{
SetForegroundWindow(hwnd);
FormUtilities.ActivateWindow(FormUtilities.GetModalWindow(hwnd));
}
}
}
#if WINFORMS // define this for Winforms apps
public void OnWndProc(System.Windows.Forms.Form form, int m, IntPtr wParam, IntPtr lParam, bool activate)
{
if (form == null)
throw new ArgumentNullException("form");
if (m == Message)
{
if (activate)
{
if (form.WindowState == System.Windows.Forms.FormWindowState.Minimized)
{
form.WindowState = System.Windows.Forms.FormWindowState.Normal;
}
form.Activate();
FormUtilities.ActivateWindow(FormUtilities.GetModalWindow(form.Handle));
}
}
}
public void OnWndProc(System.Windows.Forms.Form form, System.Windows.Forms.Message m, bool activate)
{
if (form == null)
throw new ArgumentNullException("form");
OnWndProc(form, m.Msg, m.WParam, m.LParam, activate);
}
#endif
public void ReleaseMutex()
{
Mutex.ReleaseMutex();
}
public bool WaitForMutext(bool force, IntPtr wParam, IntPtr lParam)
{
bool b = PrivateWaitForMutext(force);
if (!b)
{
PostMessage((IntPtr)HWND_BROADCAST, Message, wParam, lParam);
}
return b;
}
public bool WaitForMutext(IntPtr wParam, IntPtr lParam)
{
return WaitForMutext(false, wParam, lParam);
}
private bool PrivateWaitForMutext(bool force)
{
if (force)
return true;
try
{
return Mutex.WaitOne(TimeSpan.Zero, true);
}
catch (AbandonedMutexException)
{
return true;
}
}
}
// NOTE: don't add any field or public get/set property, as this must exactly map to Windows' WINDOWPLACEMENT structure
[StructLayout(LayoutKind.Sequential)]
public struct WindowPlacement
{
public int Length { get; set; }
public int Flags { get; set; }
public int ShowCmd { get; set; }
public int MinPositionX { get; set; }
public int MinPositionY { get; set; }
public int MaxPositionX { get; set; }
public int MaxPositionY { get; set; }
public int NormalPositionLeft { get; set; }
public int NormalPositionTop { get; set; }
public int NormalPositionRight { get; set; }
public int NormalPositionBottom { get; set; }
[DllImport("user32.dll", SetLastError = true)]
private static extern bool SetWindowPlacement(IntPtr hWnd, ref WindowPlacement lpwndpl);
[DllImport("user32.dll", SetLastError = true)]
private static extern bool GetWindowPlacement(IntPtr hWnd, ref WindowPlacement lpwndpl);
private const int SW_SHOWMINIMIZED = 2;
public bool IsMinimized
{
get
{
return ShowCmd == SW_SHOWMINIMIZED;
}
}
public bool IsValid
{
get
{
return Length == Marshal.SizeOf(typeof(WindowPlacement));
}
}
public void SetPlacement(IntPtr windowHandle)
{
SetWindowPlacement(windowHandle, ref this);
}
public static WindowPlacement GetPlacement(IntPtr windowHandle, bool throwOnError)
{
WindowPlacement placement = new WindowPlacement();
if (windowHandle == IntPtr.Zero)
return placement;
placement.Length = Marshal.SizeOf(typeof(WindowPlacement));
if (!GetWindowPlacement(windowHandle, ref placement))
{
if (throwOnError)
throw new Win32Exception(Marshal.GetLastWin32Error());
return new WindowPlacement();
}
return placement;
}
}
public static class FormUtilities
{
[DllImport("user32.dll")]
private static extern IntPtr GetWindow(IntPtr hWnd, int uCmd);
[DllImport("user32.dll", SetLastError = true)]
private static extern IntPtr SetActiveWindow(IntPtr hWnd);
[DllImport("user32.dll")]
private static extern bool IsWindowVisible(IntPtr hWnd);
[DllImport("kernel32.dll")]
public static extern int GetCurrentThreadId();
private delegate bool EnumChildrenCallback(IntPtr hwnd, IntPtr lParam);
[DllImport("user32.dll")]
private static extern bool EnumThreadWindows(int dwThreadId, EnumChildrenCallback lpEnumFunc, IntPtr lParam);
private class ModalWindowUtil
{
private const int GW_OWNER = 4;
private int _maxOwnershipLevel;
private IntPtr _maxOwnershipHandle;
private bool EnumChildren(IntPtr hwnd, IntPtr lParam)
{
int level = 1;
if (IsWindowVisible(hwnd) && IsOwned(lParam, hwnd, ref level))
{
if (level > _maxOwnershipLevel)
{
_maxOwnershipHandle = hwnd;
_maxOwnershipLevel = level;
}
}
return true;
}
private static bool IsOwned(IntPtr owner, IntPtr hwnd, ref int level)
{
IntPtr o = GetWindow(hwnd, GW_OWNER);
if (o == IntPtr.Zero)
return false;
if (o == owner)
return true;
level++;
return IsOwned(owner, o, ref level);
}
public static void ActivateWindow(IntPtr hwnd)
{
if (hwnd != IntPtr.Zero)
{
SetActiveWindow(hwnd);
}
}
public static IntPtr GetModalWindow(IntPtr owner)
{
ModalWindowUtil util = new ModalWindowUtil();
EnumThreadWindows(GetCurrentThreadId(), util.EnumChildren, owner);
return util._maxOwnershipHandle; // may be IntPtr.Zero
}
}
public static void ActivateWindow(IntPtr hwnd)
{
ModalWindowUtil.ActivateWindow(hwnd);
}
public static IntPtr GetModalWindow(IntPtr owner)
{
return ModalWindowUtil.GetModalWindow(owner);
}
}
}
[我在下面提供了控制台和wpf应用程序的示例代码。]
在创建命名的Mutex实例后，只需检查createdNew变量的值(示例如下!)。
布尔值createdNew将返回false:
如果命名为“YourApplicationNameHere”的互斥锁实例已经存在 在系统某处创建
布尔值createdNew将返回true:
如果这是第一个名为“YourApplicationNameHere”的互斥锁 系统。
控制台应用程序-示例:
static Mutex m = null;
static void Main(string[] args)
{
const string mutexName = "YourApplicationNameHere";
bool createdNew = false;
try
{
// Initializes a new instance of the Mutex class with a Boolean value that indicates
// whether the calling thread should have initial ownership of the mutex, a string that is the name of the mutex,
// and a Boolean value that, when the method returns, indicates whether the calling thread was granted initial ownership of the mutex.
using (m = new Mutex(true, mutexName, out createdNew))
{
if (!createdNew)
{
Console.WriteLine("instance is alreday running... shutting down !!!");
Console.Read();
return; // Exit the application
}
// Run your windows forms app here
Console.WriteLine("Single instance app is running!");
Console.ReadLine();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.ReadLine();
}
}
WPF-Example:
public partial class App : Application
{
static Mutex m = null;
protected override void OnStartup(StartupEventArgs e)
{
const string mutexName = "YourApplicationNameHere";
bool createdNew = false;
try
{
// Initializes a new instance of the Mutex class with a Boolean value that indicates
// whether the calling thread should have initial ownership of the mutex, a string that is the name of the mutex,
// and a Boolean value that, when the method returns, indicates whether the calling thread was granted initial ownership of the mutex.
m = new Mutex(true, mutexName, out createdNew);
if (!createdNew)
{
Current.Shutdown(); // Exit the application
}
}
catch (Exception)
{
throw;
}
base.OnStartup(e);
}
protected override void OnExit(ExitEventArgs e)
{
if (m != null)
{
m.Dispose();
}
base.OnExit(e);
}
}
这是一篇关于互斥锁解决方案的很好的文章。本文描述的方法有两个优点。
首先，它不需要依赖于Microsoft。VisualBasic组装。如果我的项目已经依赖于该程序集，我可能会建议使用另一个答案中显示的方法。但事实上，我不使用微软。VisualBasic程序集，我宁愿不向项目添加不必要的依赖项。
其次，本文将展示当用户试图启动另一个实例时，如何将应用程序的现有实例显示到前台。这是这里描述的其他互斥锁解决方案没有解决的问题。
更新
截至2014年8月1日，我上面链接的文章仍然活跃，但博客已经有一段时间没有更新了。这让我担心，它最终可能会消失，随之而来的是所倡导的解决方案。我在这里复制这篇文章的内容以供后人参考。这些文字仅属于Sanity Free Coding的博客所有者。
Today I wanted to refactor some code that prohibited my application from running multiple instances of itself. Previously I had use System.Diagnostics.Process to search for an instance of my myapp.exe in the process list. While this works, it brings on a lot of overhead, and I wanted something cleaner. Knowing that I could use a mutex for this (but never having done it before) I set out to cut down my code and simplify my life. In the class of my application main I created a static named Mutex:
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
...
}
Having a named mutex allows us to stack synchronization across multiple threads and processes which is just the magic I'm looking for. Mutex.WaitOne has an overload that specifies an amount of time for us to wait. Since we're not actually wanting to synchronizing our code (more just check if it is currently in use) we use the overload with two parameters: Mutex.WaitOne(Timespan timeout, bool exitContext). Wait one returns true if it is able to enter, and false if it wasn't. In this case, we don't want to wait at all; If our mutex is being used, skip it, and move on, so we pass in TimeSpan.Zero (wait 0 milliseconds), and set the exitContext to true so we can exit the synchronization context before we try to aquire a lock on it. Using this, we wrap our Application.Run code inside something like this:
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
static void Main() {
if(mutex.WaitOne(TimeSpan.Zero, true)) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
mutex.ReleaseMutex();
} else {
MessageBox.Show("only one instance at a time");
}
}
}
So, if our app is running, WaitOne will return false, and we'll get a message box. Instead of showing a message box, I opted to utilize a little Win32 to notify my running instance that someone forgot that it was already running (by bringing itself to the top of all the other windows). To achieve this I used PostMessage to broadcast a custom message to every window (the custom message was registered with RegisterWindowMessage by my running application, which means only my application knows what it is) then my second instance exits. The running application instance would receive that notification and process it. In order to do that, I overrode WndProc in my main form and listened for my custom notification. When I received that notification I set the form's TopMost property to true to bring it up on top. Here is what I ended up with: Program.cs
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
static void Main() {
if(mutex.WaitOne(TimeSpan.Zero, true)) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
mutex.ReleaseMutex();
} else {
// send our Win32 message to make the currently running instance
// jump on top of all the other windows
NativeMethods.PostMessage(
(IntPtr)NativeMethods.HWND_BROADCAST,
NativeMethods.WM_SHOWME,
IntPtr.Zero,
IntPtr.Zero);
}
}
}
NativeMethods.cs
// this class just wraps some Win32 stuff that we're going to use
internal class NativeMethods
{
public const int HWND_BROADCAST = 0xffff;
public static readonly int WM_SHOWME = 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);
}
Form1.cs(正面部分)
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
protected override void WndProc(ref Message m)
{
if(m.Msg == NativeMethods.WM_SHOWME) {
ShowMe();
}
base.WndProc(ref m);
}
private void ShowMe()
{
if(WindowState == FormWindowState.Minimized) {
WindowState = FormWindowState.Normal;
}
// get our current "TopMost" value (ours will always be false though)
bool top = TopMost;
// make our form jump to the top of everything
TopMost = true;
// set it back to whatever it was
TopMost = top;
}
}
您还可以使用CodeFluent Runtime，这是一组免费的工具。它提供了一个SingleInstance类来实现单个实例应用程序。
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