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.NET基于类名约定的自动依赖注入完整指南

news 来源：原创 2025/6/21 7:54:02

🚀 .NET基于类名约定的自动依赖注入完整指南

基于类名约定的自动依赖注入可大幅减少手动注册服务的工作量，本文将通过清晰的结构、美观的排版和丰富的示例，帮助你快速掌握这一实用技术。

🌈 核心特性概览

特性	说明
类名约定	自动识别以 `Service` 结尾的类（不区分大小写）
接口优先匹配	优先注册到 `I{ClassName}` 形式的接口（如 `UserService` → `IUserService`）
多生命周期支持	支持 `Transient`/`Scoped`/`Singleton` 三种生命周期
灵活扫描控制	可指定任意程序集或默认扫描调用程序集
无接口自注册	自动注册未实现接口的类为自身类型

📦 完整代码实现（含所有重载）

using Microsoft.Extensions.DependencyInjection;
using System;
using System.Linq;
using System.Reflection;/// <summary>
/// 依赖注入扩展方法集合（基于类名约定）
/// </summary>
public static class ServiceCollectionExtensions
{/// <summary>/// 自动注册以"Service"结尾的类（默认Transient生命周期）/// </summary>public static IServiceCollection AutoRegisterServices(this IServiceCollection services,Assembly assembly = null){assembly ??= Assembly.GetCallingAssembly();// 扫描规则：公共类、非抽象、非泛型、类名以Service结尾var serviceTypes = assembly.GetTypes().Where(t => t.IsClass && !t.IsAbstract && t.IsPublic &&!t.ContainsGenericParameters &&t.Name.EndsWith("Service", StringComparison.OrdinalIgnoreCase)).ToArray();// 注册服务到容器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{// 注册到所有实现的接口foreach (var @interface in interfaces){services.AddTransient(@interface, implType);}}}else{// 无接口时注册自身services.AddTransient(implType);}}return services;}/// <summary>/// 自动注册以"Service"结尾的类（支持自定义生命周期）/// </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;}// 辅助方法：获取服务类型（提取公共逻辑）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();// 辅助方法：创建服务描述符（提取公共逻辑）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);}// 返回第一个接口（避免注册多个描述符）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中注册（`Program.cs`）

var builder = WebApplication.CreateBuilder(args);// 方式1：默认Transient（扫描调用程序集）
builder.Services.AutoRegisterServices();// 方式2：指定Scoped生命周期
builder.Services.AutoRegisterServices(ServiceLifetime.Scoped);// 方式3：扫描指定程序集（如业务层）
var businessAssembly = Assembly.Load("MyBusinessLayer");
builder.Services.AutoRegisterServices(ServiceLifetime.Singleton, businessAssembly);var app = builder.Build();

2. 服务类示例（符合约定的实现）

// ✅ 示例1：接口匹配型服务
public interface IUserService { string GetInfo(); }
public class UserService : IUserService 
{public string GetInfo() => "User Service Running";
}// ✅ 示例2：多接口实现服务
public interface IAuthService { void Login(); }
public interface ILogService { void WriteLog(string msg); }
public class AuthService : IAuthService, ILogService 
{public void Login() { /* 登录逻辑 */ }public void WriteLog(string msg) { /* 日志逻辑 */ }
}// ✅ 示例3：无接口自注册服务
public class DataService 
{public void ProcessData() { /* 数据处理 */ }
}// ❌ 示例4：不符合约定的类（不会被注册）
public class ServiceHelper { }        // 类名不以Service结尾
public abstract class BaseService { } // 抽象类

🔧 扩展优化方案（带emoji标记）

1. 🌐 基于类名的生命周期自动识别

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. 📌 特性标记增强控制

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

3. ⚡ 缓存扫描结果提升性能

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 => /* 扫描规则 */).ToArray();}}return _cachedServiceTypes;
}

📝 最佳实践指南

📦 混合注册策略
- 核心服务（如DbContext）手动注册：
  services.AddDbContext<AppDbContext>(options => {...});
- 业务服务自动注册：
  builder.Services.AutoRegisterServices();

🔍 精准扫描范围

// 仅扫描当前程序集中的服务
builder.Services.AutoRegisterServices(typeof(UserService).Assembly);

✅ 单元测试验证

[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);
}