.NET 6 Worker Service获取appsettings.json连接字符串报错：Configuration不存在

报错原因是当前ConfigureServices的重载仅接收IServiceCollection参数，没有直接暴露Configuration对象，导致无法直接引用。以下是两种解决方式：

方法一：使用带HostBuilderContext的重载 #

修改ConfigureServices的委托签名，添加HostBuilderContext参数，通过该上下文对象获取配置：

using Microsoft.Extensions.Configuration;
using WorkerService;

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices((context, services) =>
    {
        services.Configure<WorkerService.DAL._DBConnStr>(context.Configuration.GetSection("ConnectionStrings"));

        services.AddHttpClient();
        services.AddHostedService<Worker>();
    })
    .Build();

await host.RunAsync();

方法二：提前构建配置对象 #

先手动构建IConfiguration实例，再在ConfigureServices中使用：

using Microsoft.Extensions.Configuration;
using WorkerService;

var configuration = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
    .AddCommandLine(args)
    .Build();

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.Configure<WorkerService.DAL._DBConnStr>(configuration.GetSection("ConnectionStrings"));

        services.AddHttpClient();
        services.AddHostedService<Worker>();
    })
    .Build();

await host.RunAsync();

额外注意事项 #

确保_DBConnStr类的属性名称与appsettings.json中ConnectionStrings下的键名一致（大小写不敏感，但建议保持匹配），示例类结构：

namespace WorkerService.DAL
{
    public class _DBConnStr
    {
        public string Sqlserver1ConnectionString { get; set; }
        public string Oracle1ConnectionString { get; set; }
        // 对应其他连接字符串的属性
    }
}

内容的提问来源于stack exchange，提问作者A.K