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
    
     ();            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
    
     ();    //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
    
     ();
    

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
    
     (Configuration.GetSection("MyOption"));
    

通过 IOptions 注入

public ConfigController(IConfiguration configuration, IOptions
    
      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){    _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
    
     ("Peter", Configuration.GetSection("Peter"));services.Configure
     
      ("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){    _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
    
     ().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
    
     (option =>{    if (option.Age == 20)    {        option.Age = 19;    }});
    

GitHub源码链接：

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

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