这篇文章主要介绍“.Net Core怎么配置Configuration”,在日常操作中,相信很多人在.Net Core怎么配置Configuration问题上存在疑惑,小编查阅了各式资料,整理出简单好用的操作方法,希望对大家解答”.Net Core怎么配置Configuration”的疑惑有所帮助!接下来,请跟着小编一起来学习吧!
核心类
构建
ConfigurationBuilder
IConfigurationSource
ConfigurationProvider
ConfigurationRoot
查询
索引器
GetSection
DBConfiguration示例
最近又研究了一下.NetCore配置选项的源码实现,又学习到了不少东西。这篇文章先写一下IConfiguration的学习成果,Options的后面补上
ConfigurationBuilder:IConfigurationBuilder (构建IConfiguration)
IConfigurationSource (配置数据来源)
IConfigurationProvider (将配置源的原始结构转为为IDictionary<string, string>)
ConfigurationRoot:IConfigurationRoot:IConfiguration (配置根节点)
下面是ConfigurationBuilder中的主要代码
可以看到ConfigurationBuilder的主要功能就是配置数据源到集合中
在Build时依次调用IConfigurationSource的Build函数,并将返回的IConfigurationProvider加入到List中
最后用IConfigurationProvider的集合构建一个ConfigurationRoot对象
public IList<IConfigurationSource> Sources = new List<IConfigurationSource>(); public IConfigurationBuilder Add(IConfigurationSource source) { Sources.Add(source); return this; } public IConfigurationRoot Build() { List<IConfigurationProvider> list = new List<IConfigurationProvider>(); foreach (IConfigurationSource source in Sources) { IConfigurationProvider item = source.Build(this); list.Add(item); } return new ConfigurationRoot(list); }
public class EnvironmentVariablesConfigurationSource : IConfigurationSource { public string Prefix; public IConfigurationProvider Build(IConfigurationBuilder builder) { return new EnvironmentVariablesConfigurationProvider(Prefix); } public EnvironmentVariablesConfigurationSource() { } } public class CommandLineConfigurationSource : IConfigurationSource { public IDictionary<string, string> SwitchMappings; public IEnumerable<string> Args; public IConfigurationProvider Build(IConfigurationBuilder builder) { return new CommandLineConfigurationProvider(Args, SwitchMappings); } public CommandLineConfigurationSource() { } } //JsonConfigurationSource继承自FileConfigurationSource,我这里将其合为一个了 public abstract class JsonConfigurationSource : IConfigurationSource { public IFileProvider FileProvider { get; set; } public string Path { get; set; } public bool Optional { get; set; } public bool ReloadOnChange { get; set; } public int ReloadDelay { get; set; } = 250; public Action<FileLoadExceptionContext> OnLoadException { get; set; } public IConfigurationProvider Build(IConfigurationBuilder builder) { FileProvider = FileProvider ?? builder.GetFileProvider(); OnLoadException = OnLoadException ?? builder.GetFileLoadExceptionHandler(); return new JsonConfigurationProvider(this); } public void ResolveFileProvider() { if (FileProvider == null && !string.IsNullOrEmpty(Path) && System.IO.Path.IsPathRooted(Path)) { string directoryName = System.IO.Path.GetDirectoryName(Path); string text = System.IO.Path.GetFileName(Path); while (!string.IsNullOrEmpty(directoryName) && !Directory.Exists(directoryName)) { text = System.IO.Path.Combine(System.IO.Path.GetFileName(directoryName), text); directoryName = System.IO.Path.GetDirectoryName(directoryName); } if (Directory.Exists(directoryName)) { FileProvider = new PhysicalFileProvider(directoryName); Path = text; } } } }
上面展示了比较常用的三种ConfigurationSource,代码都比较简单。
也很容易看出来ConfigurationSource的作用就是配置数据源,并不解析数据。
解析数据源的功能由 IConfigurationProvider完成
下面为IConfigurationProvider接口定义的5个函数
public interface IConfigurationProvider { bool TryGet(string key, out string value); void Set(string key, string value); IChangeToken GetReloadToken(); void Load(); IEnumerable<string> GetChildKeys(IEnumerable<string> earlierKeys, string parentPath); }
ConfigurationProvider是一个抽象类,继承了IConfigurationProvider接口
在新建Provider时一般都会选择直接继承ConfigurationProvider,接下来看一下ConfigurationProvider的几个核心方法
public abstract class ConfigurationProvider : IConfigurationProvider { private ConfigurationReloadToken _reloadToken = new ConfigurationReloadToken(); protected IDictionary<string, string> Data= new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); public virtual bool TryGet(string key, out string value)=>Data.TryGetValue(key, out value); public virtual void Set(string key, string value)=>Data[key] = value; public virtual void Load(){} public IChangeToken GetReloadToken() { return _reloadToken; } protected void OnReload() { ConfigurationReloadToken configurationReloadToken = Interlocked.Exchange(ref _reloadToken, new ConfigurationReloadToken()); configurationReloadToken.OnReload(); }
可以推测出:
Load函数负责从源数据读取数据然后给字典Data赋值
ConfigurationProvider将数据存储在字典Data中,增加修改都是对字典的操作
每个ConfigurationProvider都会生成一个IChangeToken,在OnReload函数被调用时生成新的Token,并调用原Token的OnReload函数
在ConfigurationBuilder的Build函数中,我们生成了一个ConfigurationRoot,并给他传递了所有的ConfigrationProvider列表,下面我们看看他用我们的Provider都做了啥吧
private ConfigurationReloadToken _changeToken = new ConfigurationReloadToken(); public ConfigurationRoot(IList<IConfigurationProvider> providers) { _providers = providers; _changeTokenRegistrations = new List<IDisposable>(providers.Count); foreach (IConfigurationProvider p in providers) { p.Load(); ChangeToken.OnChange(p.GetReloadToken, delegate{ var oldToken=Interlocked.Exchange(ref _changeToken, new ConfigurationReloadToken()); oldToken.OnReload(); }) } } public IChangeToken GetReloadToken()=>_changeToken;
上面的代码也对部分地方进行了简化。可以看到ConfigurationRoot在生成时主要就做了两件事
1.调用Provider的Load函数,这会给Provider的Data赋值
2.读取Provider的ReloadToken,每个Provider的Reload事件都会触发ConfigurationRoot自己的ReloadToken的Reload事件
至此配置的数据源构建这块就分析完啦!
常规的配置查询有两种基本方式 :索引器和GetSection(string key)
其余的GetValue等等都是一些扩展方法,本篇文章不对此进行展开研究
索引器的查询执行的方式是倒叙查询所有的Provider,然后调用Provider的TryGet函数,在查询时重名的Key,最后加入的会生效。
赋值则是依次调用每个Provider的Set函数
public string this[string key] { get { for (int num = _providers.Count - 1; num >= 0; num--) { if (_providers[num].TryGet(key, out var value)) { return value; } } return null; } set { foreach (IConfigurationProvider provider in _providers) { provider.Set(key, value); } } }
public IConfigurationSection GetSection(string key) { return new ConfigurationSection(this, key); } public class ConfigurationSection : IConfigurationSection, IConfiguration { private readonly IConfigurationRoot _root; private readonly string _path; private string _key; public string Value { get { return _root[Path]; } set { _root[Path] = value; } } //ConfigurationPath.Combine = string.Join(":",paramList); public string this[string key] { get { return _root[ConfigurationPath.Combine(Path, key)]; } set { _root[ConfigurationPath.Combine(Path, key)] = value; } } public ConfigurationSection(IConfigurationRoot root, string path) { _root = root; _path = path; } public IConfigurationSection GetSection(string key) { return _root.GetSection(ConfigurationPath.Combine(Path, key)); } public IEnumerable<IConfigurationSection> GetChildren() { return _root.GetChildrenImplementation(Path); } public IChangeToken GetReloadToken() { return _root.GetReloadToken(); } }
可以看到GetSection会生成一个ConfigurationSection对象
而ConfigurationSection在读取/设置值时实际上就是对查询的Key用:拼接,然后调用IConfigurationRoot(_root)的赋值或查询函数
关于Configuration的配置和读取的知识点大概就是以上这些了,还有更深入的涉及到对象的绑定这一块Get<> Bind<> GetChildren()等,比较难读,要一行一行代码看,以后有时间可能再研究一下
最后贴上一个从数据加载配置源并动态更新的小例子
public void Run() { var builder = new ConfigurationBuilder(); var dataProvider = new DBDataProvider(); builder.Sources.Add(new DBConfigurationSource() { DataProvider = dataProvider, ReloadOnChange = true, Table = "config" }); IConfigurationRoot config = builder.Build(); Console.WriteLine(config["time"]); Task.Run(() => { while (true) { Thread.Sleep(2000); dataProvider.Update("config"); Console.WriteLine($"读取配置时间:{config["time"]}"); } }); Thread.Sleep(20000); } public class DBConfigurationProvider : ConfigurationProvider { private DBConfigurationSource Source { get; } public DBConfigurationProvider(DBConfigurationSource source) { Source = source; } public override void Load() { if (Source.ReloadOnChange) { ChangeToken.OnChange(() => Source.DataProvider.Watch(Source.Table), LoadData); } LoadData(); } private void LoadData() { var data = Source.DataProvider.GetData(Source.Table); Load(data); OnReload(); } public void Load(Dictionary<string, object> data) { var dic = new SortedDictionary<string, string>(StringComparer.OrdinalIgnoreCase); foreach (var element in data) { dic.Add(element.Key, element.Value?.ToString()); } base.Data = dic; } } public class DBConfigurationSource : IConfigurationSource { public DBDataProvider DataProvider { get; set; } public string Table { get; set; } public bool ReloadOnChange { get; set; } public bool Optional { get; set; } public DBConfigurationSource() { } public IConfigurationProvider Build(IConfigurationBuilder builder) { return new DBConfigurationProvider(this); } } public class DBDataProvider { private ConcurrentDictionary<string, CancellationTokenSource> tableToken = new ConcurrentDictionary<string, CancellationTokenSource>(); public DBDataProvider() { } public Dictionary<string, object> GetData(string table) { switch (table) { case "config": return GetConfig(); } return new Dictionary<string, object>(); } public void Update(string table) { Console.WriteLine($"更新数据库数据table:{table}"); if (tableToken.TryGetValue(table, out CancellationTokenSource cts)) { var oldCts = cts; tableToken[table] = new CancellationTokenSource(); oldCts.Cancel(); } } private Dictionary<string, object> GetConfig() { var valueDic = new Dictionary<string, object>(); valueDic.TryAdd("time", DateTime.Now.ToString()); valueDic.TryAdd("weather", "windy"); valueDic.TryAdd("people_number:male", 100); valueDic.TryAdd("people_number:female", 150); return valueDic; } public IChangeToken Watch(string table) { var cts = tableToken.GetOrAdd(table, x => new CancellationTokenSource()); return new CancellationChangeToken(cts.Token); } }
到此,关于“.Net Core怎么配置Configuration”的学习就结束了,希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习,快去试试吧!若想继续学习更多相关知识,请继续关注亿速云网站,小编会继续努力为大家带来更多实用的文章!
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