前言

一行業務代碼還沒寫，框架代碼一大堆，不利於學習。
常看到java的學習資料或博客，標題一般為《SpringBoot 整合 XXX》，所以仿照著寫了《.NET 6 整合 Autofac 依賴註入容器》這樣一個標題。
以下是我自己的用法，可能不是最佳實踐。

一. 引用包

NuGet搜索並安裝：
Autofac
Autofac.Extensions.DependencyInjection

二. 配置代碼

var builder = WebApplication.CreateBuilder(args);

...省略

// ASP.NET Core整合Autofac
builder.Host.UseServiceProviderFactory(new AutofacServiceProviderFactory());//通過工廠替換，把Autofac整合進來
builder.Host.ConfigureContainer<ContainerBuilder>(containerBuilder =>
{
    ServiceFactory.SetBuilder(containerBuilder);
    ServiceFactory.RegisterAssembly(Assembly.GetExecutingAssembly()); //註冊服務
});

var app = builder.Build();

ServiceFactory.SetContainer((app.Services as AutofacServiceProvider).LifetimeScope as IContainer);
Task.Run(async () => await ServiceFactory.StartAllService()); //啟動服務，註意：服務啟動完成之前，調用介面會異常

...省略

三. 服務的自動註冊、啟動、停止

IService介面

/// <summary>
/// 服務介面
/// </summary>
public interface IService
{
    /// <summary>
    /// 服務啟動
    /// </summary>
    Task OnStart();

    /// <summary>
    /// 服務停止
    /// </summary>
    Task OnStop();
}

RegisterServiceAttribute特性

/// <summary>
/// 註冊為服務
/// </summary>
public class RegisterServiceAttribute : Attribute
{
}

ServiceBase抽像類

[RegisterService]
public abstract class ServiceBase : IService
{
    #region OnStart
    public virtual Task OnStart()
    {
        return Task.CompletedTask;
    }
    #endregion

    #region OnStop
    public virtual Task OnStop()
    {
        return Task.CompletedTask;
    }
    #endregion

}

ServiceFactory服務工廠類

public class ServiceFactory
{
    private static ContainerBuilder _builder;

    private static IContainer _container;

    private static bool _isRunning; //服務是否正在運行

    public static void SetBuilder(ContainerBuilder builder)
    {
        _builder = builder;
    }

    public static void SetContainer(IContainer container)
    {
        _container = container;
    }

    /// <summary>
    /// Autofac.ContainerBuilder
    /// </summary>
    public static ContainerBuilder Builder
    {
        get
        {
            return _builder;
        }
    }

    /// <summary>
    /// 獲取服務
    /// </summary>
    /// <typeparam name="T">介面類型</typeparam>
    public static T Get<T>()
    {
        if (_isRunning)
        {
            return _container.Resolve<T>();
        }
        else
        {
            throw new Exception("服務尚未啟動完成");
        }
    }

    /// <summary>
    /// 獲取服務
    /// </summary>
    /// <param name="type">介面類型</param>
    public static object Get(Type type)
    {
        if (_isRunning)
        {
            return _container.Resolve(type);
        }
        else
        {
            throw new Exception("服務尚未啟動完成");
        }
    }

    #region 註冊程式集
    /// <summary>
    /// 註冊程式集
    /// </summary>
    /// <param name="serviceAssembly">服務程式集</param>
    public static void RegisterAssembly(Assembly serviceAssembly)
    {
        Type[] typeArr = serviceAssembly.GetTypes();

        foreach (Type type in typeArr)
        {
            if (type.GetCustomAttribute<RegisterServiceAttribute>() != null && !type.IsAbstract)
            {
                _builder.RegisterType(type).SingleInstance().AsImplementedInterfaces().AsSelf();
            }
            else
            {
                Type[] interfaceTypes = type.GetInterfaces();
                foreach (Type interfaceType in interfaceTypes)
                {
                    if (interfaceType.GetCustomAttribute<RegisterServiceAttribute>() != null && !type.IsAbstract)
                    {
                        _builder.RegisterType(type).SingleInstance().AsImplementedInterfaces().AsSelf();
                        break;
                    }
                }
            }
        }

        //_container = _builder.Build();
    }
    #endregion

    #region 啟動所有服務
    /// <summary>
    /// 啟動所有服務
    /// </summary>
    public static async Task StartAllService()
    {
        Type iServiceInterfaceType = typeof(IService);
        IEnumerable<Type> types = _container.ComponentRegistry.Registrations.Select(a => a.Activator.LimitType);
        await Parallel.ForEachAsync(types, async (type, c) =>
        {
            if (iServiceInterfaceType.IsAssignableFrom(type))
            {
                object obj = _container.Resolve(type);

                try
                {
                    IService service = obj as IService;
                    await service.OnStart();
                    LogUtil.Info("服務 " + obj.GetType().FullName + " 已啟動");
                }
                catch (Exception ex)
                {
                    LogUtil.Error(ex, "服務 " + obj.GetType().FullName + " 啟動失敗");
                }
            }
        });
        _isRunning = true;
    }
    #endregion

    #region 停止所有服務
    /// <summary>
    /// 停止所有服務
    /// </summary>
    public static async Task StopAllService()
    {
        Type iServiceInterfaceType = typeof(IService);
        IEnumerable<Type> types = _container.ComponentRegistry.Registrations.Select(a => a.Activator.LimitType);
        await Parallel.ForEachAsync(types, async (type, c) =>
        {
            if (iServiceInterfaceType.IsAssignableFrom(type))
            {
                object obj = _container.Resolve(type);
                IService service = obj as IService;

                try
                {
                    await service.OnStop();
                    LogUtil.Info("服務 " + obj.GetType().FullName + " 已停止");
                }
                catch (Exception ex)
                {
                    LogUtil.Error(ex, "服務 " + obj.GetType().FullName + " 停止失敗");
                }
            }
        });
        _isRunning = false;
    }
    #endregion

}

ServiceFactory的簡寫類

/// <summary>
/// ServiceFactory的簡寫
/// </summary>
public class SF
{
    /// <summary>
    /// 獲取服務
    /// </summary>
    /// <typeparam name="T">介面類型</typeparam>
    public static T Get<T>()
    {
        return ServiceFactory.Get<T>();
    }

    /// <summary>
    /// 獲取服務
    /// </summary>
    /// <param name="type">介面類型</param>
    public static object Get(Type type)
    {
        return ServiceFactory.Get(type);
    }
}

編寫服務類

服務類示例1

/// <summary>
/// 測試服務
/// </summary>
public class TestService : ServiceBase
{
    public async Task<string> GetValue()
    {
        return await Task.FromResult("測試數據");
    }
}

服務類示例2

重寫了OnStart和OnStop以實現服務的啟動和停止。

/// <summary>
/// 定時任務管理
/// </summary>
public class ScheduleJobs : ServiceBase
{
    #region 變數
    private IScheduler _scheduler;
    #endregion

    #region OnStart
    public override async Task OnStart()
    {
        try
        {
            NameValueCollection options = new NameValueCollection();
            string schedulerName = "DefaultQuartzScheduler";
            options.Add("quartz.scheduler.instanceName", schedulerName);
            StdSchedulerFactory schedulerFactory = new StdSchedulerFactory(options);
            _scheduler = await schedulerFactory.GetScheduler(schedulerName);
            if (_scheduler == null)
            {
                _scheduler = await schedulerFactory.GetScheduler();
            }
            await _scheduler.Start();
            AddJobs(_scheduler);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
    }
    #endregion

    #region OnStop
    public override async Task OnStop()
    {
        await _scheduler.Shutdown();
    }
    #endregion

    #region ScheduleJob
    private async Task ScheduleJob<T>(IScheduler scheduler, string cronString) where T : IJob
    {
        IJobDetail jobDetail = JobBuilder.Create<T>().Build();
        ITrigger trigger = TriggerBuilder.Create().WithCronSchedule(cronString).Build();
        await scheduler.ScheduleJob(jobDetail, trigger);
    }
    #endregion

    private async void AddJobs(IScheduler scheduler)
    {
        await ScheduleJob<TestJob>(scheduler, "0/30 * * * * ?");
    }

}

構造註入示例

[ApiController]
[Route("[controller]")]
public class TestController : ControllerBase
{
    private readonly TestService _testService;

    public TestController(TestService testService)
    {
        _testService = testService;
    }

    ...省略
}

也可以這樣使用

var value = await SF.Get<TestService>().GetValue();