最近,我决定迁移用C#编写的WPF Windows桌面应用程序之一,并将。NET Framework 4.5定位于最新的。NET Core 3.1。一切都很好,直到我不得不添加对单实例应用程序的支持,同时能够将任何参数从第二个实例传递到第一个正在运行的实例。我以前对单实例应用程序的WPF实现是使用System.Runtime.Remoting,在.NET Core中不可用。因此,我不得不做一些新的事情。下面是我想出的实现。效果很好,但我认为可以改进。请随时讨论和改进建议的解决方案。
我创建了一个SingleInstanceService,它使用信号量来指示是否是第一个实例。如果是第一个实例,则创建一个TcpListener,然后无限期地等待从第二个实例传递的任何参数。如果启动了第二个实例,那么我将第二个实例的参数发送到第一个侦听实例,然后退出第二个实例。
internal class SingleInstanceService
{
internal Action<string[]> OnArgumentsReceived;
internal bool IsFirstInstance()
{
if (Semaphore.TryOpenExisting(semaphoreName, out semaphore))
{
Task.Run(() => { SendArguments(); Environment.Exit(0); });
return false;
}
else
{
semaphore = new Semaphore(0, 1, semaphoreName);
Task.Run(() => ListenForArguments());
return true;
}
}
private void ListenForArguments()
{
TcpListener tcpListener = new TcpListener(IPAddress.Parse(localHost), localPort);
try
{
tcpListener.Start();
while (true)
{
TcpClient client = tcpListener.AcceptTcpClient();
Task.Run(() => ReceivedMessage(client));
}
}
catch (SocketException ex)
{
Log.Error(ex);
tcpListener.Stop();
}
}
private void ReceivedMessage(TcpClient tcpClient)
{
try
{
using (NetworkStream networkStream = tcpClient?.GetStream())
{
string data = null;
byte[] bytes = new byte[256];
int bytesCount;
while ((bytesCount = networkStream.Read(bytes, 0, bytes.Length)) != 0)
{
data += Encoding.UTF8.GetString(bytes, 0, bytesCount);
}
OnArgumentsReceived(data.Split(' '));
}
}
catch (Exception ex)
{
Log.Error(ex);
}
}
private void SendArguments()
{
try
{
using (TcpClient tcpClient = new TcpClient(localHost, localPort))
{
using (NetworkStream networkStream = tcpClient.GetStream())
{
byte[] data = Encoding.UTF8.GetBytes(string.Join(" ", Environment.GetCommandLineArgs()));
networkStream.Write(data, 0, data.Length);
}
}
}
catch (Exception ex)
{
Log.Error(ex);
}
}
private Semaphore semaphore;
private string semaphoreName = $"Global\\{Environment.MachineName}-myAppName{Assembly.GetExecutingAssembly().GetName().Version}-sid{Process.GetCurrentProcess().SessionId}";
private string localHost = "127.0.0.1";
private int localPort = 19191;
}
然后在App.xaml.cs中,我有以下代码:
protected override void OnStartup(StartupEventArgs e)
{
SingleInstanceService singleInstanceService = new SingleInstanceService();
if (singleInstanceService.IsFirstInstance())
{
singleInstanceService.OnArgumentsReceived += OnArgumentsReceived;
// Some other calls
}
base.OnStartup(e);
}
private void OnArgumentsReceived(string[] args)
{
// ProcessCommandLineArgs(args);
}
请随时讨论这个主题,我认为这是Windows桌面开发人员中非常普遍的用例。谢谢。
使用依赖项注入。您将需要定义一个接口,然后实现该接口。在启动代码中,您将需要添加接口及其作为单例服务的实现。
在实现构造函数中,您可以只将要运行的代码放入一次。这将使对象的生存期保持不变。
还有其他类型的注入,瞬态和范围注入,但对于您的用例,您可能只需要单例。
Program.cs
using System;
using Microsoft.Extensions.DependencyInjection;
namespace example
{
class Program
{
static void Main(string[] args)
{
// create service collection
var serviceCollection = new ServiceCollection();
ConfigureServices(serviceCollection);
var serviceProvider = serviceCollection.BuildServiceProvider();
serviceProvider.GetService<Startup>().Run();
}
private static void ConfigureServices(IServiceCollection serviceCollection)
{
// add services
serviceCollection.AddTransient<IMyService, MyService>();
serviceCollection.AddTransient<Startup>();
}
}
}
Startup.cs
namespace example
{
public class Startup
{
private readonly IMyService _myService;
public Startup(IMyService myService)
{
_myService = myService;
}
public void Run()
{
_myService.MyMethod();
}
}
}
Interace
namespace example
{
public interface IMyService
{
void MyMethod();
}
}
服务的实施
namespace example
{
public class MyService : IMyService
{
public MyService()
{
// on signleton service this only gets invoked once
}
public void MyMethod()
{
// your imolmentation here
}
}
}
一些在线参考:https://dzone.com/articles/dependency-injection-in-net-core-console-applicati