常德网站seo,广告设计与制作流程,建设 网站,外贸相关岗位人才招聘启事前言上次#xff0c;我们介绍了《如何获取 ASP.NET Core 启动地址》。但是#xff0c;如果要在 BackgroundService 中获取启动地址可不那么容易#xff0c;因为 BackgroundService 在 app 启动前就开始执行了:var builder WebApplication.CreateBuilder(args);
builder.Ser…前言上次我们介绍了《如何获取 ASP.NET Core 启动地址》。但是如果要在 BackgroundService 中获取启动地址可不那么容易因为 BackgroundService 在 app 启动前就开始执行了:var builder WebApplication.CreateBuilder(args);
builder.Services.AddHostedServiceDemoBackgroundService();var app builder.Build();app.MapGet(/, () Hello My IO!);await app.StartAsync();Console.WriteLine(app.Urls.First());await app.WaitForShutdownAsync();internal class DemoBackgroundService : BackgroundService
{protected override async Task ExecuteAsync(CancellationToken stoppingToken){Console.WriteLine(BackgroundService ExecuteAsync);await Task.CompletedTask;}
}那要怎么实现呢IHostApplicationLifetime我们可以利用ASP.NET Core应用程序生存期事件等待启动完成再获取启动地址internal class DemoBackgroundService : BackgroundService
{private readonly IServiceProvider _services;private string _url;public DemoBackgroundService(IServiceProvider services, IHostApplicationLifetime lifetime){_services services;lifetime.ApplicationStarted.Register(OnAppStarted);}public void OnAppStarted(){var server _services.GetServiceIServer();_url server.Features.GetIServerAddressesFeature().Addresses.First();}protected override async Task ExecuteAsync(CancellationToken stoppingToken){while (string.IsNullOrWhiteSpace(_url)){await Task.Delay(1000); }Console.WriteLine(BackgroundService ExecuteAsync);Console.WriteLine(_url);await Task.CompletedTask;}
}现在可以正常获取 ASP.NET Core 启动地址了SemaphoreSlim轮询虽然可以解决问题但感觉不太优雅。我们可以创建一个信号灯 SemaphoreSlim在ExecuteAsync方法中等待信号灯而在启动后释放信号灯static SemaphoreSlim semaphoreSlim new SemaphoreSlim(0, 1);public void OnAppStarted()
{...semaphoreSlim.Release();
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{await semaphoreSlim.WaitAsync();...
}可以看到这样还带来了另外一个好处比上面的解决方式更快地进入到了 BackgroundService结论今天我们利用了ASP.NET Core应用程序生存期事件实现了在 BackgroundService 获取 ASP.NET Core 启动地址。添加微信号【MyIO666】邀你加入技术交流群
