一、前言

配置的本质就是字符串的键值对，微软的一系列接口其实就是对这些键值对字符串的抽象。

二、基本类型

2.1、Nuget包

• Microsoft.Extensions.Configuration.Abstractions

• Microsoft.Extensions.Configuration

2.2、抽象接口

• IConfiguration

  • 提供了查询、设置配置项、监控变化等方法

• IConfigurationRoot

  • 在IConfiguration接口基础上，增加了 Reload 方法强制从provider中重新加载配置值

• IConfigurationSection

• • 对配置节点的抽象

• IConfigurationBuilder

• • 根据提供的数据源注册并构建IConfiguration

• IConfigurationSource

• • 对数据源的抽象，例如Json、xml、环境变量、内存变量等

• IConfigurationProvider

• • 规定了配置项的获取、设置、重载等统一的行为

三、基本配置

注：各种配置方式的目的是在控制台中输出以下内容，如下图：

3.1、加载内存中的配置

• 需要引入包：Microsoft.Extensions.Configuration

• 主要方法：builder.AddInMemoryCollection()

static void Main(string[] args)
{IConfigurationBuilder builder = new ConfigurationBuilder();var memoryData = new Dictionary<string, string>();memoryData.Add("Student:Code", "10002385");memoryData.Add("Student:Name", "LiuSan");builder.AddInMemoryCollection(memoryData);IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");        Console.Read();
}

3.2、加载环境变量中的配置

• 需要引入包：Microsoft.Extensions.Configuration.EnvironmentVariables

• 主要方法：builder.AddEnvironmentVariables()

• 环境变量中层级关系使用 __ 代替 :

static void Main(string[] args)
{IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddEnvironmentVariables();IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");Console.Read();
}

3.3、加载命令行中的配置

• 需要引入包：Microsoft.Extensions.Configuration.CommandLine

• 主要方法：builder.AddCommandLine(args)

• 命令行中使用--表示配置项，层级关系使用:

• 主要在docker中使用

static void Main(string[] args)
{IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddCommandLine(args);IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");Console.Read();
}

3.4、加载Json中的配置

• 需要引入包：Microsoft.Extensions.Configuration.Json

• 主要方法：builder.AddJsonFile("appsettings.json")

static void Main(string[] args)
{IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddJsonFile("appsettings.json");IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");Console.Read();
}

3.5、加载xml中的配置

• 需要引入包：Microsoft.Extensions.Configuration.Xml

• 主要方法：builder.AddXmlFile("appsettings.xml")

• xml中不会读取最外层，所以Section必需从第二层开始

static void Main(string[] args)
{IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddXmlFile("appsettings.xml");IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");Console.Read();
}

四、高级配置

4.1、将配置绑定至强对象

• 需要引入包：Microsoft.Extensions.Configuration.Binder

• 主要方法：configurationRoot.GetSection("Student").Bind(student)

  class Program{static void Main(string[] args){IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddJsonFile("appsettings.json");IConfigurationRoot configurationRoot = builder.Build();var student = new Student();configurationRoot.GetSection("Student").Bind(student);Console.WriteLine($"Code:{student.Code}");Console.WriteLine($"Name:{student.Name}");Console.Read();}}class Student{public string Code { get; set; }public string Name { get; set; }}

4.2、IOptions

• 需要引入包：Microsoft.Extensins.Options

• 需要引入包：Microsoft.Extensions.Options.ConfigurationExtensions

• 本质其实就是将一个Section配置节点映射到一个实体对象

    class Program{static void Main(string[] args){IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddJsonFile("appsettings.json");IConfigurationRoot configurationRoot = builder.Build();IServiceCollection services = new ServiceCollection();services.Configure<WeixinOptions>(configurationRoot.GetSection("WeixinSetting"));services.AddScoped<IWeixinService, WeixinService>();var provider = services.BuildServiceProvider();var weixinService = provider.GetService<IWeixinService>();string appId = weixinService.AppId;string token = weixinService.Token;Console.Read();}}interface IWeixinService{string AppId { get; }string Token { get; }}class WeixinService: IWeixinService{IOptions<WeixinOptions> _options;public WeixinService(IOptions<WeixinOptions> options){_options = options;}public string AppId { get => _options.Value.AppId; }public string Token { get => _options.Value.Token;}}class WeixinOptions{public string AppId { get; set; }public string Token { get; set; }}

4.3、热更新

• IConfigurationBuilder添加数据源时设置reloadOnChange=true

• 监听的核心方法：var token = configurationRoot.GetReloadToken();

 static void Main(string[] args){IConfigurationBuilder builder = new ConfigurationBuilder();builder.AddJsonFile("appsettings.json", optional:false, reloadOnChange:true);IConfigurationRoot configurationRoot = builder.Build();IConfigurationSection configurationSection = configurationRoot.GetSection("Student");var token = configurationRoot.GetReloadToken();ChangeToken.OnChange(() => configurationRoot.GetReloadToken(), () => {Console.WriteLine("配置发生改变了...");Console.WriteLine($"Code:{configurationSection["Code"]}");Console.WriteLine($"Name:{configurationSection["Name"]}");});           Console.Read();}

五、总结

• 配置就是key-value键值对字符串

• IConfiguration和IConfigurationRoot是对键值对的抽象

• IConfigurationBuilder用于构建IConfiguration和IConfigurationRoot

• IConfigurationSource是对数据源的抽象

• IConfigurationProvider将不同来源的IConfigurationSource 转为统一的模型

• IOptions方便将不同的配置节点(Path)映射为对应的强类型对象

• IConfigurationBuilder添加多个数据源（IConfigurationSource）后，如果key重名，则以最后一个配置为准(覆盖前面)