如何在启动时启动服务 (`IServiceCollection`)

Question

我有一个单例服务，我希望 运行 在启动时等待一些 Controller 通过依赖注入构建服务。

该服务处理来自服务总线的数据，它似乎没有正确依赖客户端流量。最干净的初始化方法是什么？

Answer 1

哦，在Startup.cs里面引用就行了，不用配置

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    // Has message bus connection
    services.AddSingleton<ISomeRespository, SomeRepository>();

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(... ISomeRespository db)
{

呃 :)

Answer 2

通常您会正常实例化服务，然后将其引用传递给 AddSingleton() 方法。

var someRepository = new SomeRepository(/*pass in configuration and dependencies*/);

// pass instance of the already instantiated service
services.AddSingleton<ISomeRespository>(someRepository);

编辑

或者预热扩展方法：

public static class WarmupServiceProviderExtensions
{
    public static void WarmUp(this IServiceProvider app)
    {
        // Just call it to resolve, no need to safe a reference
        app.RequestService<ISomeRepository>();
    }
}

在你的 Startup.cs

public void Configure(IServiceProvider app) 
{
    app.UseXyz(...);

    // warmup/initailize your services
    app.WarmUp();
}