如何在我的WinForms应用程序的另一个进程实例中调用方法？

Question

我正在开发一个应用程序，使用Mutex确保它是在系统上运行的唯一实例。

当另一个应用程序实例尝试启动时，我希望在原始实例中运行一个方法。

我找到了一些使用RegisterWindowMessage/PostMessage Win32 API的示例，将消息发送到HWND_BROADCAST，但我无法使它们工作，并且我在其他地方读到使用HWND_BROADCAST可能会有危险。

是否有更好的方法来实现这一点，而不需要应用程序在特权模式下运行？

- Daniel Schaffer

---

如果你想要一个hacky的方法（我是指非常hacky），当第二个应用程序实例启动时，在某个临时位置创建一些虚拟文件，并使用FileSystemWatcher监视该临时位置以获取新创建的文件。当它检测到新文件已被创建时，执行你需要做的操作 :) - BFree

Answer 1

这是我写的一个小助手。

使用方法：

var pipeListener = new NamedPipeListener<String>(); // instantiate an instance
pipeListener.MessageReceived += (sender, e) => MessageBox.Show(e.Message); // when a message is received, show a messagebox with the message
pipeListener.Error += (sender, e) => MessageBox.Show("Error ({0}): {1}", e.ErrorType, e.Exception.Message); // oh noes!
pipeListener.Start(); // when you're ready, start listening

来自另一个进程：

NamedPipeListener<String>.SendMessage("Howdy howdy howdy");

注意，它使用PipeListener的全名作为管道的默认名称。如果您需要更细致的控制，可以使用接受管道名称的构造函数重载。

以下是该类：

using System;
using System.IO.Pipes;
using System.Runtime.Serialization.Formatters.Binary;

namespace FunWithNamedPipes
{
    /// <summary>Contains event data for <see cref="NamedPipeMessageReceiveHandler{TMessage}" /> events.</summary>
    /// <typeparam name="TMessage"></typeparam>
    public class NamedPipeListenerMessageReceivedEventArgs<TMessage> : EventArgs
    {
        /// <summary>Initializes an instance of <see cref="NamedPipeListenerMessageReceivedEventArgs{TMessage}" /> with the specified <paramref name="message" />.</summary>
        /// <param name="message">The message passed by the event.</param>
        public NamedPipeListenerMessageReceivedEventArgs(TMessage message)
        {
            this.Message = message;
        }

        /// <summary>Gets the message passed by the event.</summary>
        public TMessage Message { get; private set; }
    }

    /// <summary>Contains event data for <see cref="NamedPipeListenerErrorEventHandler" /> events.</summary>
    public class NamedPipeListenerErrorEventArgs : EventArgs
    {
        /// <summary>Initializes an instance of <see cref="NamedPipeListenerErrorEventArgs" /> with the specified <paramref name="errorType" /> and <paramref name="exception" />.</summary>
        /// <param name="errorType">A <see cref="NamedPipeListenerErrorType" /> describing the part of the listener process where the error was caught.</param>
        /// <param name="ex">The <see cref="Exception" /> that was thrown.</param>
        public NamedPipeListenerErrorEventArgs(NamedPipeListenerErrorType errorType, Exception ex)
        {
            this.ErrorType = errorType;
            this.Exception = ex;
        }

        /// <summary>Gets a <see cref="NamedPipeListenerErrorType" /> describing the part of the listener process where the error was caught.</summary>
        public NamedPipeListenerErrorType ErrorType { get; private set; }

        /// <summary>Gets the <see cref="Exception" /> that was caught.</summary>
        public Exception Exception { get; private set; }
    }

    /// <summary>Represents a method that will handle an event where a message is received via named pipes.</summary>
    /// <typeparam name="TMessage">The type of message that will be received.</typeparam>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The event data passed by the event, which includes the message that was received.</param>
    public delegate void NamedPipeMessageReceivedHandler<TMessage>(Object sender, NamedPipeListenerMessageReceivedEventArgs<TMessage> e);

    /// <summary>Represents a method that will handle an event that is fired when an exception is caught.</summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The event data passed by the event, included the error type and exception that was caught.</param>
    public delegate void NamedPipeMessageErrorHandler(Object sender, NamedPipeListenerErrorEventArgs e);

    /// <summary>Includes different types of errors that describe where in the listening process an exception was caught.</summary>
    public enum NamedPipeListenerErrorType : byte
    {
        /// <summary>Indicates that an exception was caught while calling <see cref="NamedPipeServerStream.BeginWaitForConnection" />.</summary>
        BeginWaitForConnection = 1,

        /// <summary>Indicates that an exception was caught while calling <see cref="NamedPipeServerStream.EndWaitForConnection" />.</summary>
        EndWaitForConnection = 2,

        /// <summary>Indicates that an exception was caught while deserializing a message received from the named pipe.</summary>
        DeserializeMessage = 3,

        /// <summary>Indicates that an exception was caught while closing or disposing a used named pipe.</summary>
        CloseAndDisposePipe = 4,

        /// <summary>Indicates that an exception was caught while invoking the <see cref="NamedPipeListener{TMessage}.MessageReceived"/> event.</summary>
        NotifyMessageReceived = 5
    }

    /// <summary>A helper class for sending and receiving messages using named pipes.</summary>
    /// <typeparam name="TMessage">The type of message that will be sent or received.</typeparam>
    public class NamedPipeListener<TMessage> : IDisposable
    {
        /// <summary>Occurs when a message is received.</summary>
        public event NamedPipeMessageReceivedHandler<TMessage> MessageReceived;

        /// <summary>Occurs when an exception is caught.</summary>
        public event NamedPipeMessageErrorHandler Error;

        static readonly String DEFAULT_PIPENAME = typeof(NamedPipeListener<TMessage>).FullName;
        static readonly BinaryFormatter formatter = new BinaryFormatter();

        NamedPipeServerStream pipeServer;

        /// <summary>Initializes a new instance of <see cref="NamedPipeListener{TMessage}" /> using the specified <paramref name="pipeName" />.</summary>
        /// <param name="pipeName">The name of the named pipe that will be used to listen on.</param>
        public NamedPipeListener(String pipeName)
        {
            this.PipeName = pipeName;
        }

        /// <summary>Initializes a new instance of <see cref="NamedPipeListener{TMessage}" /> using the default pipe name.</summary>
        /// <remarks>The default pipe name is the full name of the type of the instance.</remarks>
        public NamedPipeListener()
            : this(DEFAULT_PIPENAME) { }

        /// <summary>The name of the named pipe that will be used to listen on.</summary>
        public String PipeName { get; private set; }

        /// <summary>Starts listening on the named pipe specified for the instance.</summary>
        internal void Start()
        {
            if (pipeServer == null) pipeServer = new NamedPipeServerStream(DEFAULT_PIPENAME, PipeDirection.In, 1, PipeTransmissionMode.Message, PipeOptions.Asynchronous);

            try { pipeServer.BeginWaitForConnection(new AsyncCallback(PipeConnectionCallback), null); }
            catch (Exception ex) { this.OnError(NamedPipeListenerErrorType.BeginWaitForConnection, ex); }
        }

        private void PipeConnectionCallback(IAsyncResult result)
        {
            try
            {
                pipeServer.EndWaitForConnection(result);
            }
            catch (Exception ex)
            {
                this.OnError(NamedPipeListenerErrorType.EndWaitForConnection, ex);
                return;
            }

            TMessage message;
            try
            {
                message = (TMessage)formatter.Deserialize(pipeServer);
            }
            catch (Exception ex)
            {
                this.OnError(NamedPipeListenerErrorType.DeserializeMessage, ex);
                return;
            }

            try
            {
                this.OnMessageReceived(new NamedPipeListenerMessageReceivedEventArgs<TMessage>(message));
            }
            catch (Exception ex)
            {
                this.OnError(NamedPipeListenerErrorType.NotifyMessageReceived, ex);
                return;
            }

            if (this.End())
            {
                this.Start();
            }
        }

        internal Boolean End()
        {
            try
            {
                pipeServer.Close();
                pipeServer.Dispose();
                pipeServer = null;

                return true;
            }
            catch (Exception ex)
            {
                this.OnError(NamedPipeListenerErrorType.CloseAndDisposePipe, ex);
                return false;
            }
        }

        private void OnMessageReceived(TMessage message)
        {
            this.OnMessageReceived(new NamedPipeListenerMessageReceivedEventArgs<TMessage>(message));
        }

        protected virtual void OnMessageReceived(NamedPipeListenerMessageReceivedEventArgs<TMessage> e)
        {
            if (this.MessageReceived != null)
            {
                this.MessageReceived(this, e);
            }
        }

        private void OnError(NamedPipeListenerErrorType errorType, Exception ex)
        {
            this.OnError(new NamedPipeListenerErrorEventArgs(errorType, ex));
        }

        protected virtual void OnError(NamedPipeListenerErrorEventArgs e)
        {
            if (this.Error != null)
            {
                this.Error(this, e);
            }
        }

        void IDisposable.Dispose()
        {
            if(pipeServer != null)
            {
                try { pipeServer.Disconnect(); }
                catch { }

                try { pipeServer.Close(); }
                catch { }

                try { pipeServer.Dispose(); }
                catch { }
            }
        }

        /// <summary>Sends the specified <paramref name="message" /> to the default named pipe for the message.</summary>        
        /// <param name="message">The message to send.</param>
        public static void SendMessage(TMessage message)
        {
            NamedPipeListener<TMessage>.SendMessage(DEFAULT_PIPENAME, message);
        }

        /// <summary>Sends the specified <paramref name="message" /> to the specified named pipe.</summary>
        /// <param name="pipeName">The name of the named pipe the message will be sent to.</param>
        /// <param name="message">The message to send.</param>
        public static void SendMessage(String pipeName, TMessage message)
        {
            using (var pipeClient = new NamedPipeClientStream(".", DEFAULT_PIPENAME, PipeDirection.Out, PipeOptions.None))
            {
                pipeClient.Connect();

                formatter.Serialize(pipeClient, message);
                pipeClient.Flush();

                pipeClient.WaitForPipeDrain();
                pipeClient.Close();
            }
        }
    }
}

- Daniel Schaffer

---

在您的SendMessage()重载中，使用pipeName时，应该写成"new NamedPipeClientStream(".", pipeName, ..."。 - IngoB

Answer 2

我之前进行过研究 - 您可以使用内存映射文件，本文http://www.codeproject.com/KB/cs/singleinstanceapplication.aspx中有示例，或者您可以像我一样（简单的方法）利用VB.NET功能（具体来说，是让您创建单个实例应用程序并调用当前运行实例中传递命令行参数的方法[因此您可以使用它来调用应用程序中的方法]）。我知道在C#中使用VB类听起来有点差劲，但这是最抽象和最简单的方法。相关文章链接 - http://www.codeproject.com/KB/cs/CSSIApp.aspx，http://msdn.microsoft.com/en-us/magazine/cc163741.aspx的最后一部分。

- Zhanger

---

这个技巧非常可行，效果很好。当我的应用程序被固定到Win7任务栏时，我曾使用它从“最近的”菜单中调用运行实例。 - AlfredBr

是的，这是一种相当简单但有效的方法，但对于某些人（包括我自己），使用VB类可能有点困难。 - Zhanger

我会使用命名管道，因为它们不需要任何 PInvoking 并且可以在 C# 中本地运行，无需任何额外的引用。这个原则与上面提到的第一篇 CodeProject 文章相同，只是你可以通过使用命名管道来使代码真正变得简洁。那篇文章已经有6年了... - BenSwayne