.NET Core 3.0 使用 IHostApplicationLifetime 处理应用启动和停止事件

IHostedService

该接口中有两个方法：

StartAsync：当应用程序主机准备启动服务时触发

StopAsync：当应用程序主机准备停止服务时触发

//
// 摘要:
//     /// Defines methods for objects that are managed by the host. ///
public interface IHostedService
{
    //
    // 摘要:
    //     /// Triggered when the application host is ready to start the service. ///
    //
    // 参数:
    //   cancellationToken:
    //     Indicates that the start process has been aborted.
    Task StartAsync(CancellationToken cancellationToken);

    //
    // 摘要:
    //     /// Triggered when the application host is performing a graceful shutdown. ///
    //
    // 参数:
    //   cancellationToken:
    //     Indicates that the shutdown process should no longer be graceful.
    Task StopAsync(CancellationToken cancellationToken);
}

IHostApplicationLifetime

该接口中包含三个属性：Host程序的启动、正在停止、已停止，一个方法StopApplication，该方法用于主动停止程序。

//
// 摘要:
//     /// Allows consumers to be notified of application lifetime events. ///
public interface IHostApplicationLifetime
{
    //
    // 摘要:
    //     /// Triggered when the application host has fully started. ///
    CancellationToken ApplicationStarted
    {
        get;
    }

    //
    // 摘要:
    //     /// Triggered when the application host is performing a graceful shutdown. ///
    //     Shutdown will block until this event completes. ///
    CancellationToken ApplicationStopped
    {
        get;
    }

    //
    // 摘要:
    //     /// Triggered when the application host is performing a graceful shutdown. ///
    //     Shutdown will block until this event completes. ///
    CancellationToken ApplicationStopping
    {
        get;
    }

    //
    // 摘要:
    //     /// Requests termination of the current application. ///
    void StopApplication();
}

这里实现IHostedService接口，然后使用IHostApplicationLifetime（该接口由框架自动实现注入），在IHostedService的StartAsync方法中注册IHostApplicationLifetime中的三个程序运行事件，可以做一些自定义的操作，我这里只是记录了日志。

internal class LifetimeEventsHostedService : IHostedService
{
    private readonly string appCode = ConfigurationManager.GetAppSetting("AppCode");
    private readonly string appName = ConfigurationManager.GetAppSetting("AppName");
    private readonly IHostApplicationLifetime _appLifetime;

    public LifetimeEventsHostedService(IHostApplicationLifetime appLifetime)
    {
        _appLifetime = appLifetime;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        _appLifetime.ApplicationStarted.Register(OnStarted);
        _appLifetime.ApplicationStopping.Register(OnStopping);
        _appLifetime.ApplicationStopped.Register(OnStopped);

        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }

    private void OnStarted()
    {
        var interNetworkV6 = System.Net.Sockets.AddressFamily.InterNetworkV6;
        var interNetwork = System.Net.Sockets.AddressFamily.InterNetwork;
        var ipList = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces()
          .Select(p => p.GetIPProperties())
          .SelectMany(p => p.UnicastAddresses)
          .Where(p => (p.Address.AddressFamily == interNetwork || p.Address.AddressFamily == interNetworkV6) && !System.Net.IPAddress.IsLoopback(p.Address)).ToList();

        Console.WriteLine($"OnStarted has been called：【{appCode}】【{appName}】【{DateTime.Now}】 【{ipList[1].Address}】 【{ipList[0].Address}】");
        Logger.Info($"OnStarted has been called：【{appCode}】【{appName}】【{DateTime.Now}】 【{ipList[1].Address}】 【{ipList[0].Address}】");
    }

    private void OnStopping()
    {
        Console.WriteLine($"OnStopping has been called：【{appCode}】【{appName}】【{DateTime.Now}】");
        Logger.Info($"OnStopping has been called：【{appCode}】【{appName}】【{DateTime.Now}】");
    }

    private void OnStopped()
    {
        Console.WriteLine($"OnStopped has been called：【{appCode}】【{appName}】【{DateTime.Now}】");
        Logger.Info($"OnStopped has been called：【{appCode}】【{appName}】【{DateTime.Now}】");
    }
}

最后在服务中注入

.ConfigureServices(a =>
{
    a.AddSingleton<IHostedService, LifetimeEventsHostedService>();
});