.NET Core依赖注入中如何注入Unity示例中的验证类？

首先需要明确：.NET Core原生DI没有Unity那样的命名注册+直接指定构造注入参数的原生语法，我们可以通过两种方式实现你要的效果，具体取决于你的.NET版本：

第一步：确保目标类的构造函数依赖正确 #

你的Customer和Lead类需要接收对应的验证类作为构造参数，示例实现如下：

public class Customer : ICustomer
{
    private readonly IValidation<ICustomer> _validator;

    // 构造函数注入验证类
    public Customer(IValidation<ICustomer> validator)
    {
        _validator = validator;
    }

    // 实现ICustomer的属性
    public string CustomerName { get; set; }
    public string PhoneNumber { get; set; }
    public decimal BillAmount { get; set; }
    public DateTime BillDate { get; set; }
    public string Address { get; set; }

    // 调用验证类的逻辑
    public void Validation()
    {
        _validator.Validate(this);
    }
}

public class Lead : ICustomer
{
    private readonly IValidation<ICustomer> _validator;

    public Lead(IValidation<ICustomer> validator)
    {
        _validator = validator;
    }

    // 实现ICustomer的属性
    public string CustomerName { get; set; }
    public string PhoneNumber { get; set; }
    public decimal BillAmount { get; set; }
    public DateTime BillDate { get; set; }
    public string Address { get; set; }

    public void Validation()
    {
        _validator.Validate(this);
    }
}

方法一：.NET 8及以上推荐使用Keyed服务 #

.NET 8新增了Keyed服务特性，可以直接为同接口的不同实现标记区分键，完美替代Unity的命名注册逻辑：

服务注册代码 #

var builder = WebApplication.CreateBuilder(args);

// 1. 注册带Key的验证类
builder.Services.AddKeyedScoped<IValidation<ICustomer>, CustomerValidationAll>("CustomerValidator");
builder.Services.AddKeyedScoped<IValidation<ICustomer>, LeadValidation>("LeadValidator");

// 2. 注册Customer和Lead，指定注入对应Key的验证类
builder.Services.AddScoped<Customer>(sp => 
    new Customer(sp.GetRequiredKeyedService<IValidation<ICustomer>>("CustomerValidator")));
builder.Services.AddScoped<Lead>(sp => 
    new Lead(sp.GetRequiredKeyedService<IValidation<ICustomer>>("LeadValidator")));

// 3. 注册工厂函数，模拟Unity的Resolve<T>(name)逻辑
builder.Services.AddScoped<Func<string, ICustomer>>(sp => customerType =>
{
    return customerType switch
    {
        "Customer" => sp.GetRequiredService<Customer>(),
        "Lead" => sp.GetRequiredService<Lead>(),
        _ => throw new ArgumentException($"不支持的客户类型：{customerType}")
    };
});

使用方式 #

在需要获取实例的地方注入Func<string, ICustomer>即可：

public class DemoService
{
    private readonly Func<string, ICustomer> _customerFactory;

    public DemoService(Func<string, ICustomer> customerFactory)
    {
        _customerFactory = customerFactory;
    }

    public void TestValidation()
    {
        // 获取Customer实例（已注入CustomerValidationAll）
        ICustomer customer = _customerFactory("Customer");
        customer.CustomerName = "";
        try
        {
            customer.Validation(); // 会触发完整验证
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

        // 获取Lead实例（已注入LeadValidation）
        ICustomer lead = _customerFactory("Lead");
        lead.PhoneNumber = "";
        try
        {
            lead.Validation(); // 仅触发姓名和手机号验证
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

方法二：.NET 7及以下版本的实现方式 #

低版本没有Keyed服务，我们可以直接注册验证类的具体类型，再在构造目标类时指定依赖：

服务注册代码 #

var builder = WebApplication.CreateBuilder(args);

// 1. 注册验证类的具体类型
builder.Services.AddScoped<CustomerValidationAll>();
builder.Services.AddScoped<LeadValidation>();

// 2. 注册Customer和Lead，直接注入对应验证类
builder.Services.AddScoped<Customer>(sp => 
    new Customer(sp.GetRequiredService<CustomerValidationAll>()));
builder.Services.AddScoped<Lead>(sp => 
    new Lead(sp.GetRequiredService<LeadValidation>()));

// 3. 同样注册工厂函数
builder.Services.AddScoped<Func<string, ICustomer>>(sp => customerType =>
{
    return customerType switch
    {
        "Customer" => sp.GetRequiredService<Customer>(),
        "Lead" => sp.GetRequiredService<Lead>(),
        _ => throw new ArgumentException($"不支持的客户类型：{customerType}")
    };
});

使用方式 #

和方法一完全一致，注入Func<string, ICustomer>后根据类型字符串获取实例即可。

内容的提问来源于stack exchange，提问作者QueenBee