基于.NET Core的跨平台开发，配置文件与之前.NET Framework采用xml的config文件不同，目前主要是采用json文件键值对配置方式读取。

参考网上相关资料总结如下：

一. 引入扩展 System.Configuration.ConfigurationManager

Nuget 下载扩展，Install-Package System.Configuration.ConfigurationManager

使用方式：添加配置文件App.config。读取方式与原.NET Framework方式一致

优点：兼容.NET Framework 原有配置方式

缺点：项目运行过程中若需修改App.config文件，对项目中输出的内容没有丝毫影响，Debug发现获取到的值的确没有变化，需要重新编译才生效。

二. 引入扩展 Microsoft.Extensions.Options.ConfigurationExtensions

Nuget 下载扩展，

Install-Package Microsoft.Extensions.Options.ConfigurationExtensions

Install-Package Microsoft.Extensions.Configuration.FileExtensions

Install-Package Microsoft.Extensions.Configuration.Json

使用方式：参考微软官网

优点：可以读取application.json中的配置参数，不再使用XML可以说很好的贴近Core的设计理念

缺点：运行时修改json文件读取到的内容不会改变，但是至少重启项目可以修改，若要运行时候修改json文件监听实现监听变化。查看源码，可以发现 虽然配置信息是通过AddSingleton注入的
但同时也注入了IOptionsChangeTokenSource ，故只需要在获取配置信息时将IOptions<> 替换为 IOptionsMonitor<>(通过监听的Option来获取信息)，并通过 IOptionsMonitor<>.CurrentValue获取即可实时获取到最新的配置信息(存在修改监听)

另外就是，这个方法采用的是反序列化的原理，也就是必须有一个跟配置文件对应的实体类才可以，这个感觉比较鸡肋，放弃。

三. 自定义扩展方法，这个实现自己写，原理是监听文件是否变更，来刷新Configuration 配置实现。

参考园友一个实现，具体需要是否有效，要花时间实践一下，原链接地址，代码如下：

public class ConfigurationManager
 {
 /// <summary>
 /// 配置内容
 /// </summary>
 private static NameValueCollection _configurationCollection = new NameValueCollection();

 /// <summary>
 /// 配置监听响应链堆栈
 /// </summary>
 private static Stack<KeyValuePair<string, FileSystemWatcher>> FileListeners = new Stack<KeyValuePair<string, FileSystemWatcher>>();

 /// <summary>
 /// 默认路径
 /// </summary>
 private static string _defaultPath = Directory.GetCurrentDirectory() + "\\appsettings.json";

 /// <summary>
 /// 最终配置文件路径
 /// </summary>
 private static string _configPath = null;

 /// <summary>
 /// 配置节点关键字
 /// </summary>
 private static string _configSection = "AppSettings";

 /// <summary>
 /// 配置外连接的后缀
 /// </summary>
 private static string _configUrlPostfix = "Url";

 /// <summary>
 /// 最终修改时间戳
 /// </summary>
 private static long _timeStamp = 0L;

 /// <summary>
 /// 配置外链关键词，例如：AppSettings.Url
 /// </summary>
 private static string _configUrlSection { get { return _configSection + "." + _configUrlPostfix; } }


 static ConfigurationManager()
 {
 ConfigFinder(_defaultPath);
 }

 /// <summary>
 /// 确定配置文件路径
 /// </summary>
 private static void ConfigFinder(string Path)
 {
 _configPath = Path;
 JObject config_json = new JObject();
 while (config_json != null)
 {
 config_json = null;
 FileInfo config_info = new FileInfo(_configPath);
 if (!config_info.Exists) break;

 FileListeners.Push(CreateListener(config_info));
 config_json = LoadJsonFile(_configPath);
 if (config_json[_configUrlSection] != null)
 _configPath = config_json[_configUrlSection].ToString();
 else break;
 }

 if (config_json == null || config_json[_configSection] == null) return;

 LoadConfiguration();
 }

 /// <summary>
 /// 读取配置文件内容
 /// </summary>
 private static void LoadConfiguration()
 {
 FileInfo config = new FileInfo(_configPath);
 var configColltion = new NameValueCollection();
 JObject config_object = LoadJsonFile(_configPath);
 if (config_object == null || !(config_object is JObject)) return;
 
 if (config_object[_configSection]!=null)
 {
 foreach (JProperty prop in config_object[_configSection])
 {
 configColltion[prop.Name] = prop.Value.ToString();
 }
 }
 
 _configurationCollection = configColltion;
 }

 /// <summary>
 /// 解析Json文件
 /// </summary>
 /// <param name="FilePath">文件路径</param>
 /// <returns></returns>
 private static JObject LoadJsonFile(string FilePath)
 {
 JObject config_object = null;
 try
 {
 StreamReader sr = new StreamReader(FilePath, Encoding.Default);
 config_object = JObject.Parse(sr.ReadToEnd());
 sr.Close();
 }
 catch { }
 return config_object;
 }

 /// <summary>
 /// 添加监听树节点
 /// </summary>
 /// <param name="info"></param>
 /// <returns></returns>
 private static KeyValuePair<string, FileSystemWatcher> CreateListener(FileInfo info)
 {

 FileSystemWatcher watcher = new FileSystemWatcher();
 watcher.BeginInit();
 watcher.Path = info.DirectoryName;
 watcher.Filter = info.Name;
 watcher.IncludeSubdirectories = false;
 watcher.EnableRaisingEvents = true;
 watcher.NotifyFilter = NotifyFilters.Attributes | NotifyFilters.CreationTime | NotifyFilters.DirectoryName | NotifyFilters.FileName | NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.Size;
 watcher.Changed += new FileSystemEventHandler(ConfigChangeListener);
 watcher.EndInit();

 return new KeyValuePair<string, FileSystemWatcher>(info.FullName, watcher);
 
 }

 private static void ConfigChangeListener(object sender, FileSystemEventArgs e)
 {
 long time = TimeStamp();
 lock (FileListeners)
 {
 if (time > _timeStamp)
 {
 _timeStamp = time;
 if (e.FullPath != _configPath || e.FullPath == _defaultPath)
 {
 while (FileListeners.Count > 0)
 {
 var listener = FileListeners.Pop();
 listener.Value.Dispose();
 if (listener.Key == e.FullPath) break;
 }
 ConfigFinder(e.FullPath);
 }
 else
 {
 LoadConfiguration();
 }
 }
 }
 }

 private static long TimeStamp()
 {
 return (long)((DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds * 100);
 }

 private static string c_configSection = null;
 public static string ConfigSection
 {
 get { return _configSection; }
 set { c_configSection = value; }
 }


 private static string c_configUrlPostfix = null;
 public static string ConfigUrlPostfix
 {
 get { return _configUrlPostfix; }
 set { c_configUrlPostfix = value; }
 }

 private static string c_defaultPath = null;
 public static string DefaultPath
 {
 get { return _defaultPath; }
 set { c_defaultPath = value; }
 }

 public static NameValueCollection AppSettings
 {
 get { return _configurationCollection; }
 }

 /// <summary>
 /// 手动刷新配置，修改配置后，请手动调用此方法，以便更新配置参数
 /// </summary>
 public static void RefreshConfiguration()
 {
 lock (FileListeners)
 {
 //修改配置
 if (c_configSection != null) { _configSection = c_configSection; c_configSection = null; }
 if (c_configUrlPostfix != null) { _configUrlPostfix = c_configUrlPostfix; c_configUrlPostfix = null; }
 if (c_defaultPath != null) { _defaultPath = c_defaultPath; c_defaultPath = null; }
 //释放掉全部监听响应链
 while (FileListeners.Count > 0)
 FileListeners.Pop().Value.Dispose();
 ConfigFinder(_defaultPath);
 }
 }

 }