.Net Core配置Configuration具體實(shí)現(xiàn)

更新時(shí)間：2021年09月07日 15:13:06 作者：張三~~

這篇文章主要介紹了.Net Core配置Configuration具體實(shí)現(xiàn)，文中運(yùn)用大量代碼進(jìn)行講解，如果有對(duì)相關(guān)知識(shí)感興趣的小伙伴可以參考這篇文章，希望可以幫助到你

核心類

ConfigurationBuilder:IConfigurationBuilder (構(gòu)建IConfiguration)
IConfigurationSource （配置數(shù)據(jù)來源）
IConfigurationProvider （將配置源的原始結(jié)構(gòu)轉(zhuǎn)為為IDictionary<string, string>）
ConfigurationRoot:IConfigurationRoot:IConfiguration （配置根節(jié)點(diǎn)）

構(gòu)建

ConfigurationBuilder

下面是ConfigurationBuilder中的主要代碼

可以看到ConfigurationBuilder的主要功能就是配置數(shù)據(jù)源到集合中

在Build時(shí)依次調(diào)用IConfigurationSource的Build函數(shù)，并將返回的IConfigurationProvider加入到List中

最后用IConfigurationProvider的集合構(gòu)建一個(gè)ConfigurationRoot對(duì)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);
}

IConfigurationSource

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繼承自FileConfigurationSource，我這里將其合為一個(gè)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;
   }
  }
 }
}

上面展示了比較常用的三種ConfigurationSource，代碼都比較簡單。

也很容易看出來ConfigurationSource的作用就是配置數(shù)據(jù)源，并不解析數(shù)據(jù)。

解析數(shù)據(jù)源的功能由 IConfigurationProvider完成

ConfigurationProvider

下面為IConfigurationProvider接口定義的5個(gè)函數(shù)

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是一個(gè)抽象類，繼承了IConfigurationProvider接口

在新建Provider時(shí)一般都會(huì)選擇直接繼承ConfigurationProvider，接下來看一下ConfigurationProvider的幾個(gè)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();
 }

可以推測出：

Load函數(shù)負(fù)責(zé)從源數(shù)據(jù)讀取數(shù)據(jù)然后給字典Data賦值
ConfigurationProvider將數(shù)據(jù)存儲(chǔ)在字典Data中，增加修改都是對(duì)字典的操作
每個(gè)ConfigurationProvider都會(huì)生成一個(gè)IChangeToken,在OnReload函數(shù)被調(diào)用時(shí)生成新的Token，并調(diào)用原Token的OnReload函數(shù)

ConfigurationRoot

在ConfigurationBuilder的Build函數(shù)中，我們生成了一個(gè)ConfigurationRoot，并給他傳遞了所有的ConfigrationProvider列表，下面我們看看他用我們的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;

上面的代碼也對(duì)部分地方進(jìn)行了簡化?？梢钥吹紺onfigurationRoot在生成時(shí)主要就做了兩件事

1.調(diào)用Provider的Load函數(shù)，這會(huì)給Provider的Data賦值
2.讀取Provider的ReloadToken,每個(gè)Provider的Reload事件都會(huì)觸發(fā)ConfigurationRoot自己的ReloadToken的Reload事件

至此配置的數(shù)據(jù)源構(gòu)建這塊就分析完啦！

查詢

常規(guī)的配置查詢有兩種基本方式：索引器和GetSection(string key)

其余的GetValue等等都是一些擴(kuò)展方法，本篇文章不對(duì)此進(jìn)行展開研究

索引器

索引器的查詢執(zhí)行的方式是倒敘查詢所有的Provider，然后調(diào)用Provider的TryGet函數(shù)，在查詢時(shí)重名的Key，最后加入的會(huì)生效。

賦值則是依次調(diào)用每個(gè)Provider的Set函數(shù)

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);
  }
 }
}

GetSection

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會(huì)生成一個(gè)ConfigurationSection對(duì)象

而ConfigurationSection在讀取/設(shè)置值時(shí)實(shí)際上就是對(duì)查詢的Key用:拼接，然后調(diào)用IConfigurationRoot（_root）的賦值或查詢函數(shù)

關(guān)于Configuration的配置和讀取的知識(shí)點(diǎn)大概就是以上這些了，還有更深入的涉及到對(duì)象的綁定這一塊Get<> Bind<> GetChildren()等，比較難讀，要一行一行代碼看，以后有時(shí)間可能再研究一下

最后貼上一個(gè)從數(shù)據(jù)加載配置源并動(dòng)態(tài)更新的小例子

DBConfiguration示例

 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($"讀取配置時(shí)間：{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($"更新數(shù)據(jù)庫數(shù)據(jù)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);
    }
}

到此這篇關(guān)于.Net Core配置Configuration具體實(shí)現(xiàn)的文章就介紹到這了,更多相關(guān).Net Core Configuration內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

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