在.Net 6 Worker服务中使用appsettings.json

Question

我想添加一个依赖于appsettings的单例服务吗。

在.Net 6工作者服务启动时，我该如何做到这一点？

using AutoMapper;
var mapperConfig = new MapperConfiguration(mc =>
{
mc.AddProfile(new MappingProfile());
});
IMapper mapper = mapperConfig.CreateMapper();
IHost host = Host.CreateDefaultBuilder(args)
.ConfigureServices(services =>
{
services.AddHostedService<Worker>();
services.AddSingleton(mapper);
services.AddSingleton<IOrderNumberGenerator, OrderNumberGenerator>();
services.AddSingleton(new ServiceIwantToCall(<--I need too use apsettings here-->));
})
.Build();
await host.RunAsync();

Answer 1

目前您正在尝试注册ServiceIwantToCall的实例。相反，您可以注册一个工厂方法来解析一个，一旦解析，它将成为一个singleton。例如，这个匿名方法：

services.AddSingleton(serviceProvider => { 
// resolve the configuration provider from the container
IConfiguration config = serviceProvider.GetRequiredService<IConfiguration>();
// get the config value and instantiate a ServiceIwantToCall
// return the instantiated service
string someValue = config["myValueKey"];
return new ServiceIwantToCall(someValue);
});