asp.net core 读取 appsettings.json 节点值

方法一直接读取JSON节点值：

  "AppSettings": {
"CacheDays": 30,
}

public string GetIntelligenceApiUrl
        {
            get
            {
                var cacheDays = new ConfigurationHelper().Get<string>("AppSettings:CacheDays");
                return cacheDays;
            }
        }

方法一的操作类：

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Configuration.Json;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using System.IO;

    /// <summary>
    /// 读取配置文件
    /// </summary>
    public class ConfigurationHelper
    {
        public IConfiguration _config { get; set; }

        public ConfigurationHelper()
        {
            _config = new ConfigurationBuilder()
            .Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true })//ReloadOnChange = true 当appsettings.json被修改时重新加载
            .Build();
        }

        public T GetAppSettings<T>(string key) where T : class, new()
        {
            var appconfig = new ServiceCollection()
                .AddOptions()
                .Configure<T>(_config.GetSection(key))
                .BuildServiceProvider()
                .GetService<IOptions<T>>()
                .Value;
            return appconfig;
        }

        public T Get<T>(string key)
        {
            IConfiguration config = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json", true, true).Build();

            return config.GetSection(key).Get<T>();
        }

        //public T GetAppsettings<T>(string key) where T : class, new()
        //{
        //    string keyDir = System.IO.Directory.GetCurrentDirectory();

        //    IConfiguration config = new ConfigurationBuilder()
        //        .SetBasePath(keyDir)
        //        .Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true })//ReloadOnChange = true 当appsettings.json被修改时重新加载
        //        .Build();
        //    var appconfig = new ServiceCollection()
        //        .AddOptions()
        //        .Configure<T>(config.GetSection(key))
        //        .BuildServiceProvider()
        //        .GetService<IOptions<T>>()
        //        .Value;
        //    return appconfig;
        //}

        /// <summary>
        /// 通过强类型绑定读取配置
        /// </summary>
        /// <typeparam name="Entity">要绑定的类型</typeparam>
        /// <param name="keyPath">配置文件路径</param>
        /// <returns>绑定的类</returns>
        public Entity GetSectionObject<Entity>(string keyPath = null) where Entity : new()
        {
            var entity = new Entity();
            if (string.IsNullOrEmpty(keyPath))
            {
                //将appsettings.json全部配置绑定到模型
                _config.Bind(entity);
            }
            else
            {
                //将指定路径下的配置项绑定到模型
                var section = _config.GetSection(keyPath);
                section.Bind(entity);
            }
            return entity;
        }
    }

方法二通过注入方式：

using Microsoft.Extensions.Configuration;

    public class AppSettingOptions : IAppSetting
    {
        public AppSettingOptions()
        {
            var configBuilder = new ConfigurationBuilder();
            configBuilder.AddJsonFile("appsettings.json");
            var config = configBuilder.Build();
            var section = config.GetSection("AppSettings");
            section.Bind(this);
        }

        public int CacheDays { get; set; }

    }

    public interface ISingle
    {
    }

    public interface IScope
    {
    }

    public interface ITrans
    {
    }

    public interface IAppSetting : IScope { }

方法二注入：

        readonly AppSettingOptions _config;

        public BoProcessIntelligenceShareHolder(IAppSetting config)
        {
            _config = (AppSettingOptions)config;
        }