.netcore中appsetting.json中配置取项

1.在服务层的类中获取依赖IConfiguration config，它会自动获得json内容

//appsetting.json
{
  "Wx": {
    "Appid": "wx1a1ddfe11f25528a"
  }
}
//WxService类的构造函数
private readonly string? m_wxAppid;
public WxService(IConfiguration config) {
   m_wxAppid = config["Wx:Appid"];
}

 2.在第一种方法的基础加一个类的映射

//新写的类
public class WxSettings
{
  public string Appid { get; set; }
}

//Program.cs中注册依赖
builder.Services.Configure<WxSettings>(builder.Configuration.GetSection("Wx"));

//要用的类中获得依赖
private readonly IOptions<WxSettings> _wxSettings;
public WxService(IOptions<WxSettings> wxSettings) {
   _wxSettings = wxSettings;
}