2.2.3 核心模塊--配置

• IConfiguration
• Options

ASP.NET Core 中的配置：https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/configuration/?view=aspnetcore-5.0

IConfiguration

• IConfiguration 的使用
• 層級對象配置到 key-value 鍵值對轉換
• 通過環境變量修改日誌級別
• 通過命令行修改日誌級別

IConfiguration 的使用

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

新增 ConfigController.cs

namespace HelloApi.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class ConfigController : Controller
    {
        private readonly IConfiguration _configuration;

        public ConfigController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpGet]
        public IActionResult GetConfigurations()
        {
            var result = new List<string>();

            foreach (var key in _configuration.AsEnumerable())
            {
                result.Add($"Key: {key.Key}, value: {key.Value}");
            }

            return Ok(result);
        }
    }
}

啟動程序，訪問：https://localhost:5001/config

不僅得到 appsettings.json 的配置， 還可以得到環境變量配置

可以在 ConfigureAppConfiguration 中清除所有配置，再添加自己需要的配置，後面添加的配置會覆蓋前面的配置

.ConfigureAppConfiguration((hostingContext, config) =>
{
    config.Sources.Clear();

    var env = hostingContext.HostingEnvironment;

    config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
})

啟動程序，訪問：https://localhost:5001/config

這樣可以得到自己添加的配置

層級對象配置到 key-value 鍵值對轉換

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

通過冒號讀取下一級配置（Windows），Linux 上通過下劃線

[HttpGet]
public IActionResult GetConfigurations()
{
    var result = new List<string>();

    //foreach (var key in _configuration.AsEnumerable())
    //{
    //    result.Add($"Key: {key.Key}, value: {key.Value}");
    //}

    return Content(string.Format("Default Log Level: {0}", _configuration["Logging:LogLevel:Default"]));
}

啟動程序，輸出如下：

Default Log Level: Debug

通過環境變量修改日誌級別

在 launcSettings.json 中添加 Trace 日誌級別

"environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development",
        "Logging__LogLevel__Default": "Trace"
      }

在 CreateHostBuilder 的時候添加環境變量配置

config.AddEnvironmentVariables();

啟動程序，輸出如下：

Default Log Level: Trace

通過命令行修改日誌級別

CreateHostBuilder

config.AddCommandLine(source =>
{
    source.Args = args;
});

在命令行中設置

set Logging__LogLevel__Default=Warning

Options

• 通過 ConfigurationBinder 操作 Options
• 通過 Configure 綁定 Option

通過 ConfigurationBinder 操作 Options

新建 MyOption.cs

namespace HelloApi
{
    public class MyOption
    {
        public string Name { get; set; }

        public int Age { get; set; }
    }
}

在 appsettings.json 中新增一個節點

"MyOption": {
    "Name": "Mingson",
    "Age": 25 
  },

在 ConfigureServices 中綁定

var myOption = new MyOption();
Configuration.GetSection("MyOption").Bind(myOption);
// 單例注入到全局中
services.AddSingleton(myOption);

在 ConfigController 中注入，與獲取

private readonly MyOption _myOption;

public ConfigController(IConfiguration configuration, MyOption myOption)
{
    _configuration = configuration;
    _myOption = myOption;
}

[HttpGet("option")]
public IActionResult GetOption()
{
    return Ok(_myOption);
}

啟動程序，訪問：https://localhost:5001/config/option

輸出如下：

{"name":"Mingson","age":25}

通過 Get 的方式

myOption = Configuration.GetSection("MyOption").Get<MyOption>();

通過 Configure 綁定 Option

IOptions

• IOptions 被註冊為 singletone，不支持為可命名的配置
• IOptionsSnapshot 被註冊為 scoped，支持為可命名的配置
• IOptionsMonitor 被註冊為 singletone，會被通知，支持重載配置，支持為可命名的配置

IOptions

// 直接注入到容器中
services.Configure<MyOption>(Configuration.GetSection("MyOption"));

通過 IOptions 注入

public ConfigController(IConfiguration configuration, IOptions<MyOption> myOption)
{
    _configuration = configuration;
    _myOption = myOption.Value;
}

啟動程序可以得到同樣的輸出

IOptionsSnapshot

public ConfigController(IConfiguration configuration, IOptionsSnapshot<MyOption> myOption)
{
    _configuration = configuration;
    _myOption = myOption.Value;
}

啟動程序，修改配置，刷新瀏覽器，可以獲取到修改後的配置

可命名的配置

appsettings.json

"Jack": {
    "Name": "Jack",
    "Age": 16
  },
  "Peter": {
    "Name": "Peter",
    "Age": 18
  }

MyOption.cs

public const string PETER = "Peter";

public const string JACK = "Jack";

ConfigureServices

services.Configure<MyOption>("Peter", Configuration.GetSection("Peter"));
services.Configure<MyOption>("Jack", Configuration.GetSection("Jack"));

ConfigController

_myOption = myOption.Get(MyOption.PETER);
_myOption = myOption.Get(MyOption.JACK);

啟動程序即可讀取不同命名的配置

IOptionsMonitor

public ConfigController(IConfiguration configuration, IOptionsMonitor<MyOption> myOption)
{
    _configuration = configuration;
    _myOption = myOption.CurrentValue;

    // 配置變化處理
    myOption.OnChange(option =>
    {

    });
}

option 驗證

屬性驗證標籤

namespace HelloApi
{
    public class MyConfigOptions
    {
        public const string MyConfig = "MyConfig";

        [RegularExpression(@"^[a-zA-Z''-'\s]{1,40}$")]
        public string Key1 { get; set; }

        [Range(0, 1000, ErrorMessage = "Value for {0} must be between {1} and {2}.")]
        public int Key2 { get; set; }

        public int Key3 { get; set; }
    }
}

綁定後校驗

ConfigureServices

services.AddOptions<MyOption>().Bind(Configuration.GetSection("MyOption")).ValidateDataAnnotations();

MyOption

[Range(1, 20)]
public int Age { get; set; }

啟動程序，輸出如下：

OptionsValidationException: DataAnnotation validation failed for members: 'Age' with the error: 'The field Age must be between 1 and 20.'.

PostConfigure

當配置被讀取出來的時候會被執行

services.PostConfigure<MyOption>(option =>
{
    if (option.Age == 20)
    {
        option.Age = 19;
    }
});

GitHub源碼鏈接：

https://github.com/MINGSON666/Personal-Learning-Library/tree/main/ArchitectTrainingCamp/HelloApi