C# .NET如何自动实现依赖注入（DI）

csharp 复制代码

namespace DialysisSOPSystem.Infrastructure
{
    public static class ServiceCollectionExtensions
    {
        /// <summary>
        /// 批量注入服务
        /// </summary>
        /// <param name="services"></param>
        /// <returns></returns>
        public static IServiceCollection RegisterAutoInjectServices(this IServiceCollection services)
        {
            ArgumentNullException.ThrowIfNull(services);

            //获取当前Host运行依赖的程序集
            var context = DependencyContext.Default;
            var assemblies = context.RuntimeLibraries
                .SelectMany(lib => lib.GetDefaultAssemblyNames(context))
                .Select(Assembly.Load)
                .ToList();
            services.Scan(scan => scan
                     .FromAssemblies(assemblies)
                     .AddClasses(classes => classes.AssignableTo<ITransientDependency>())
                     .AsImplementedInterfaces()
                     .WithTransientLifetime()
                     .AddClasses(classes => classes.AssignableTo<IScopedDependency>())
                     .AsImplementedInterfaces()
                     .WithScopedLifetime()
                     .AddClasses(classes => classes.AssignableTo<ISingletonDependency>())
                     .AsImplementedInterfaces()
                     .WithSingletonLifetime());
            return services;
        }
    }
}

csharp 复制代码

namespace DialysisSOPSystem.Infrastructure
{
    public interface ITransientDependency { }

    public interface IScopedDependency { }

    public interface ISingletonDependency { }
}

 //1、Transient(瞬态)：每次从容器 （IServiceProvider）中获取的时候都是一个新的实例
 //2、Singleton(单例)：每次从同根容器中（同根 IServiceProvider）获取的时候都是同一个实例
 //3、Scoped（应用程序域单例）：每次从同一个容器中获取的实例是相同的、

csharp 复制代码

Startup类
public void ConfigureServices(IServiceCollection services)
{
    services.RegisterAutoInjectServices();

    // 添加控制器
    services.AddControllers();

    // 添加Swagger
    services.AddEndpointsApiExplorer();
    services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new() { Title = "Dialysis SOP API", Version = "v1" });
    });

    // 添加AutoMapper
    services.AddAutoMapper(typeof(Startup).Assembly);
}

csharp 复制代码

//这段代码获取程序集，上面的web引用service和接口、仓储
 var context = DependencyContext.Default;
            var assemblies = context.RuntimeLibraries
                .SelectMany(lib => lib.GetDefaultAssemblyNames(context))
                .Select(Assembly.Load)
                .ToList();
 //只能拿到当前所在的类库下的程序集
//var assemblies = AppDomain.CurrentDomain.GetAssemblies();
//或者显示引用，就不在web把其他依赖项拉进去

// 从指定路径加载程序集
var assemblyPath = Path.Combine(AppContext.BaseDirectory, "YourProject.Services.dll");
var serviceAssembly = Assembly.LoadFrom(assemblyPath);
// 添加到 DI 扫描范围
var assemblies = new[] { serviceAssembly }.Concat(AppDomain.CurrentDomain.GetAssemblies());