2.2.3 核心模块--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
• 层级对象配置到 key-value 键值对转换
• 通过环境变量修改日志级别
• 通过命令行修改日志级别

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);
        }
    }
}

启动程序，访问：https://localhost:5001/config

不仅得到 appsettings.json 的配置， 还可以得到环境变量配置

可以在 ConfigureAppConfiguration 中清除所有配置，再添加自己需要的配置，后面添加的配置会覆盖前面的配置

.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);
})

启动程序，访问：https://localhost:5001/config

这样可以得到自己添加的配置

层级对象配置到 key-value 键值对转换

appsettings.json

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

通过冒号读取下一级配置（Windows），Linux 上通过下划线

[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"]));
}

启动程序，输出如下：

Default Log Level: Debug

通过环境变量修改日志级别

在 launcSettings.json 中添加 Trace 日志级别

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

在 CreateHostBuilder 的时候添加环境变量配置

config.AddEnvironmentVariables();

启动程序，输出如下：

Default Log Level: Trace

通过命令行修改日志级别

CreateHostBuilder

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

在命令行中设置

set Logging__LogLevel__Default=Warning

Options

• 通过 ConfigurationBinder 操作 Options
• 通过 Configure 绑定 Option

通过 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 中新增一个节点

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

在 ConfigureServices 中绑定

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

在 ConfigController 中注入，与获取

private readonly MyOption _myOption;

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

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

启动程序，访问：https://localhost:5001/config/option

输出如下：

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

通过 Get 的方式

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

通过 Configure 绑定 Option

IOptions

• IOptions 被注册为 singletone，不支持为可命名的配置
• IOptionsSnapshot 被注册为 scoped，支持为可命名的配置
• IOptionsMonitor 被注册为 singletone，会被通知，支持重载配置，支持为可命名的配置

IOptions

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

通过 IOptions 注入

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

启动程序可以得到同样的输出

IOptionsSnapshot

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

启动程序，修改配置，刷新浏览器，可以获取到修改后的配置

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);

启动程序即可读取不同命名的配置

IOptionsMonitor

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

    // 配置变化处理
    myOption.OnChange(option =>
    {

    });
}

option 验证

属性验证标签

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; }
    }
}

绑定后校验

ConfigureServices

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

MyOption

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

启动程序，输出如下：

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

PostConfigure

当配置被读取出来的时候会被执行

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

GitHub源码链接：

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