Spectre.Console.Cli注入服务的几种姿势-数字星空

Spectre.Console大家可能都不陌生,写控制台程序美化还是不错的,支持着色,表格,图标等相当nice,如果对这个库不熟悉我强烈推荐你了解一下,对于写一些CLI小工具还是相当方便的, 本文主要讲讲 Spectre.Console.Cli的服务注入, TA是 Spectre.Console 库的一部分，用于创建命令行界面（CLI）应用程序。它提供了一个强大且易于使用的API来定义命令、参数和选项，同时支持 Spectre.Console 的丰富输出格式化功能。

一个官方极简的例子,定义一个GreetCommand:

public class GreetCommand : Command<GreetCommand.Settings>
{
    public class Settings : CommandSettings
    {
        [CommandArgument(0, "<name>")]
        [Description("The name of the person to greet.")]
        public string Name { get; set; }

        [CommandOption("-r|--repeat <times>")]
        [Description("The number of times to repeat the greeting.")]
        [DefaultValue(1)]
        public int Repeat { get; set; }
    }
    public override int Execute(CommandContext context, Settings settings)
    {
        for (int i = 0; i < settings.Repeat; i++)
        {
            Console.WriteLine($"Hello, {settings.Name}!");
        }
        return 0;
    }
}

接下来，在程序的入口点配置Command

public class Program
{
    public static int Main(string[] args)
    {
        var app = new CommandApp();
        app.Configure(config =>
        {
            config.AddCommand<GreetCommand>("greet");
        });
        return app.Run(args);
    }
}

对于Spectre.Console.Cli的常规使用我这里不做过多介绍,感兴趣的同学可以移步官方文档,本文主要讲一下在CLI程序中如何注入服务

那么我们需要在GreetCommand中注入服务应该怎么做呢? 比如下面的一个服务:

public class HelloService(ILogger<HelloService> logger)
{
    public Task<string> SayHello(string name, int age)
    {
        //注入的logger
        logger.LogInformation("SayHello called with name:{name},age:{age}", name, age);
        return Task.FromResult($"Hello,My name is {name}, I`m {age} years old!");
    }
}

其实Spectre.Console.Cli内置了最简单的方式,我们只需要在app.Configure中完成:

var services = new ServiceCollection();
//添加服务
services.AddSingleton<HelloService>();
//添加日志
services.AddLogging(config =>
{
    config.AddConsole();
});
var sp = services.BuildServiceProvider();

app.Configure(config =>
{
    //添加Commands
    config.AddCommand<OneCommand>("one");
    config.AddCommand<AnotherCommand>("another");
    //注册Services
    config.Settings.Registrar.RegisterInstance(sp.GetRequiredService<HelloService>());
});

注册的服务就可以直接使用了:

public class HelloCommand(HelloService helloService) : AsyncCommand<HelloCommand.HelloSettings>
{
    private readonly HelloService _helloService = helloService;
    public class HelloSettings : CommandSettings
    {
        [CommandArgument(0, "<name>")]
        [Description("The target to say hello to.")]
        public string Name { get; set; } = null!;
    }
    public override async Task<int> ExecuteAsync(CommandContext context, HelloSettings settings)
    {
        var message = await _helloService.SayHello(settings.Name, settings.Age);
        AnsiConsole.MarkupLine($"[blue]{message}[/]");
        return 0;
    }
}

另外的一个注入方式是实现ITypeRegistrar,官方提供MSDI的用例,自己也可以实现Autofac等其他DI,下面是MSDI的实现:

namespace Infrastructure
{
    public sealed class MsDITypeRegistrar(IServiceCollection services) : ITypeRegistrar
    {
        private readonly IServiceCollection _services =
            services ?? throw new ArgumentNullException(nameof(services));
        public ITypeResolver Build()
        {
            return new TypeResolver(_services.BuildServiceProvider());
        }
        public void Register(Type service, Type implementation)
        {
            _services.AddSingleton(service, implementation);
        }
        public void RegisterInstance(Type service, object implementation)
        {
            _services.AddSingleton(service, implementation);
        }
        public void RegisterLazy(Type service, Func<object> factory)
        {
            _services.AddSingleton(service, (provider) => factory());
        }
    }
    internal sealed class TypeResolver(IServiceProvider provider) : ITypeResolver
    {
        public object? Resolve(Type? type)
        {
            if (provider is null || type is null)
            {
                return null;
            }
            return ActivatorUtilities.GetServiceOrCreateInstance(provider, type);
        }
    }
}

使用的话只需要实例化CommandApp时候传入MsDITypeRegistrar即可:

var services = new ServiceCollection();
//添加服务...

var app = new CommandApp(new MsDITypeRegistrar(services));
app.Configure(config =>
{
   //...
});
return app.Run(args);

除了上面的方式,我们其实还可以使用ICommandInterceptor切面的方式来完成注入的操作:

下面我们定义一个AutoDIAttribute特性,实现一个AutoDIInterceptor的拦截器,后者主要给标记了AutoDI的属性服务赋值

[AttributeUsage(AttributeTargets.Property, Inherited = true)]
public class AutoDIAttribute : Attribute{ }

/// <summary>
/// 自动注入的拦截器
/// </summary>
internal class AutoDIInterceptor(IServiceProvider serviceProvider) : ICommandInterceptor
{
    public void Intercept(CommandContext context, CommandSettings settings)
    {
        var type = settings.GetType();
        var properties = type.GetProperties();
        foreach (var property in properties)
        {
            var isAutoInject = property.GetCustomAttributes<AutoDIAttribute>(true).Any();
            if (isAutoInject)
            {
                var service = ActivatorUtilities.GetServiceOrCreateInstance(serviceProvider, property.PropertyType);
                property.SetValue(settings, service);
            }
        }
    }
}

接下来在CommandSettings中标记需要自动注入服务的属性,如下面的HelloService:

internal class AutoDICommand : AsyncCommand<AutoDICommand.AnotherInjectSettings>
{
    public class AnotherInjectSettings : CommandSettings
    {
        /// <summary>
        /// 使用切面装载的服务
        /// </summary>
        [AutoDI]
        public HelloService HelloService { get; set; } = null!;

        [Description("user name")]
        [DefaultValue("vipwan"), CommandOption("-n|--name")]
        public string Name { get; set; } = null!;

        [Description("user age")]
        [DefaultValue(12), CommandOption("-a|--age")]
        public int Age { get; set; }
    }

    public override async Task<int> ExecuteAsync(CommandContext context, AnotherInjectSettings settings)
    {
        var message = await settings.HelloService.SayHello(settings.Name, settings.Age);
        AnsiConsole.MarkupLine($"[green]{message}[/]");
        return 0;
    }
}

然后在app.Configure中使用AutoDIInterceptor切面:

var services = new ServiceCollection();
//添加服务
services.AddSingleton<HelloService>();
var sp = services.BuildServiceProvider();

app.Configure(config =>
{
    //设置自动注入的拦截器
    config.SetInterceptor(new AutoDIInterceptor(sp));
    config.AddCommand<AutoDICommand>("di");
    //...
});

然后测试运行程序: