🚀 .NET基于類名約定的自動依賴注入完整指南

基于類名約定的自動依賴注入可大幅減少手動注冊服務的工作量，本文將通過清晰的結構、美觀的排版和豐富的示例，幫助你快速掌握這一實用技術。

🌈 核心特性概覽

特性	說明
類名約定	自動識別以 Service 結尾的類（不區分大小寫）
接口優先匹配	優先注冊到 I{ClassName} 形式的接口（如 UserService → IUserService）
多生命周期支持	支持 Transient/Scoped/Singleton 三種生命周期
靈活掃描控制	可指定任意程序集或默認掃描調用程序集
無接口自注冊	自動注冊未實現接口的類為自身類型

📦 完整代碼實現（含所有重載）

using Microsoft.Extensions.DependencyInjection;
using System;
using System.Linq;
using System.Reflection;/// <summary>
/// 依賴注入擴展方法集合（基于類名約定）
/// </summary>
public static class ServiceCollectionExtensions
{/// <summary>/// 自動注冊以"Service"結尾的類（默認Transient生命周期）/// </summary>public static IServiceCollection AutoRegisterServices(this IServiceCollection services,Assembly assembly = null){assembly ??= Assembly.GetCallingAssembly();// 掃描規則：公共類、非抽象、非泛型、類名以Service結尾var serviceTypes = assembly.GetTypes().Where(t => t.IsClass && !t.IsAbstract && t.IsPublic &&!t.ContainsGenericParameters &&t.Name.EndsWith("Service", StringComparison.OrdinalIgnoreCase)).ToArray();// 注冊服務到容器foreach (var implType in serviceTypes){var interfaces = implType.GetInterfaces();if (interfaces.Any()){// 匹配I{ClassName}接口（如UserService→IUserService）var matchingInterface = interfaces.FirstOrDefault(i => i.Name == "I" + implType.Name);if (matchingInterface != null){services.AddTransient(matchingInterface, implType);}else{// 注冊到所有實現的接口foreach (var @interface in interfaces){services.AddTransient(@interface, implType);}}}else{// 無接口時注冊自身services.AddTransient(implType);}}return services;}/// <summary>/// 自動注冊以"Service"結尾的類（支持自定義生命周期）/// </summary>public static IServiceCollection AutoRegisterServices(this IServiceCollection services,ServiceLifetime lifetime,Assembly assembly = null){assembly ??= Assembly.GetCallingAssembly();var serviceTypes = GetServiceTypes(assembly);foreach (var implType in serviceTypes){var interfaces = implType.GetInterfaces();var descriptor = CreateServiceDescriptor(implType, interfaces, lifetime);services.Add(descriptor);}return services;}// 輔助方法：獲取服務類型（提取公共邏輯）private static Type[] GetServiceTypes(Assembly assembly) =>assembly.GetTypes().Where(t => t.IsClass && !t.IsAbstract && t.IsPublic &&!t.ContainsGenericParameters &&t.Name.EndsWith("Service", StringComparison.OrdinalIgnoreCase)).ToArray();// 輔助方法：創建服務描述符（提取公共邏輯）private static ServiceDescriptor CreateServiceDescriptor(Type implType, Type[] interfaces, ServiceLifetime lifetime){if (interfaces.Any()){var matchingInterface = interfaces.FirstOrDefault(i => i.Name == "I" + implType.Name);if (matchingInterface != null){return new ServiceDescriptor(matchingInterface, implType, lifetime);}// 返回第一個接口（避免注冊多個描述符）return new ServiceDescriptor(interfaces[0], implType, lifetime);}return new ServiceDescriptor(implType, implType, lifetime);}
}

🚀 使用示例（清晰排版）

1. 在ASP.NET Core中注冊（Program.cs）

var builder = WebApplication.CreateBuilder(args);// 方式1：默認Transient（掃描調用程序集）
builder.Services.AutoRegisterServices();// 方式2：指定Scoped生命周期
builder.Services.AutoRegisterServices(ServiceLifetime.Scoped);// 方式3：掃描指定程序集（如業務層）
var businessAssembly = Assembly.Load("MyBusinessLayer");
builder.Services.AutoRegisterServices(ServiceLifetime.Singleton, businessAssembly);var app = builder.Build();

2. 服務類示例（符合約定的實現）

// ? 示例1：接口匹配型服務
public interface IUserService { string GetInfo(); }
public class UserService : IUserService 
{public string GetInfo() => "User Service Running";
}// ? 示例2：多接口實現服務
public interface IAuthService { void Login(); }
public interface ILogService { void WriteLog(string msg); }
public class AuthService : IAuthService, ILogService 
{public void Login() { /* 登錄邏輯 */ }public void WriteLog(string msg) { /* 日志邏輯 */ }
}// ? 示例3：無接口自注冊服務
public class DataService 
{public void ProcessData() { /* 數據處理 */ }
}// ? 示例4：不符合約定的類（不會被注冊）
public class ServiceHelper { }        // 類名不以Service結尾
public abstract class BaseService { } // 抽象類

🔧 擴展優化方案（帶emoji標記）

1. 🌐 基于類名的生命周期自動識別

private static ServiceLifetime GetLifetimeFromName(string className)
{if (className.Contains("Singleton", StringComparison.OrdinalIgnoreCase))return ServiceLifetime.Singleton;if (className.Contains("Scoped", StringComparison.OrdinalIgnoreCase))return ServiceLifetime.Scoped;return ServiceLifetime.Transient;
}

2. 📌 特性標記增強控制

[AttributeUsage(AttributeTargets.Class)]
public class AutoRegisterAttribute : Attribute 
{public ServiceLifetime Lifetime { get; set; } = ServiceLifetime.Transient;public bool IsEnabled { get; set; } = true;
}

3. ? 緩存掃描結果提升性能

private static readonly object LockObj = new();
private static Type[] _cachedServiceTypes;private static Type[] GetCachedServiceTypes(Assembly assembly)
{if (_cachedServiceTypes == null){lock (LockObj){_cachedServiceTypes = assembly.GetTypes().Where(t => /* 掃描規則 */).ToArray();}}return _cachedServiceTypes;
}

📝 最佳實踐指南

1. 📦 混合注冊策略

   • 核心服務（如DbContext）手動注冊：
     services.AddDbContext<AppDbContext>(options => {...});
   • 業務服務自動注冊：
     builder.Services.AutoRegisterServices();

2. 🔍 精準掃描范圍

   // 僅掃描當前程序集中的服務
   builder.Services.AutoRegisterServices(typeof(UserService).Assembly);
   

3. ? 單元測試驗證

   [Fact]
   public void Should_Resolve_Service_By_Convention()
   {var services = new ServiceCollection();services.AutoRegisterServices(typeof(IAuthService).Assembly);var provider = services.BuildServiceProvider();var service = provider.GetService<IAuthService>();Assert.NotNull(service);
   }