依赖注入新视角：ASP.NET Core中方法注入如何破解构造器注入困局

public classOrderService
{
    privatereadonly IPaymentGateway _paymentGateway;
    privatereadonly INotificationService _notificationService;

    public OrderService(
        IPaymentGateway paymentGateway, 
        INotificationService notificationService)
    {
        _paymentGateway = paymentGateway ?? thrownew ArgumentNullException();
        _notificationService = notificationService ?? thrownew ArgumentNullException();
    }
}

services.AddSingleton<OrderService>(); 
services.AddScoped<IPaymentGateway>(); // 生命周期不匹配

// 需要mock所有依赖项
var service = new OrderService(
    Mock.Of<IPaymentGateway>(), 
    Mock.Of<INotificationService>());

public class OrderService
{
    public void ProcessOrder(
        Order order, 
        IPaymentGateway paymentGateway)
    {
        paymentGateway.Process(order);
    }
}

public classLoggingMiddleware
{
    privatereadonly RequestDelegate _next;
    
    public LoggingMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(
        HttpContext context, 
        ILogger<LoggingMiddleware> logger)
    {
        logger.LogInformation("请求处理中...");
        await _next(context);
    }
}

[ApiController]
[Route("api/orders")]
public class OrdersController : ControllerBase
{
    [HttpPost]
    public IActionResult ProcessOrder(
        [FromBody] Order order, 
        [FromServices] IPaymentGateway gateway)
    {
        gateway.Process(order);
        return Ok();
    }
}

是否所有方法都需要相同依赖？
├── 是 → 构造器注入
└── 否 → 
    ├── 依赖项具有不同生命周期 → 方法注入
    ├── 需要参数级控制 → 方法注入
    └── 类职责过度膨胀 → 优先重构类设计