目录核心类 构建ConfigurationBuilder IConfigurationSource ConfigurationProvider ConfigurationRoot 查
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
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：
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
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);
}
}
到此这篇关于.net core配置Configuration具体实现的文章就介绍到这了,更多相关.Net Core Configuration内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
--结束END--
本文标题: .Net Core配置Configuration具体实现
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