依賴注入

官網(wǎng)介紹

https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.2

Scrutor

• 開源地址https://github.com/khellang/Scrutor
• 參考文檔 https://www.cnblogs.com/catcher1994/p/10316928.html
  手動(dòng)管理依賴注入過于麻煩,當(dāng)有多個(gè)倉(cāng)儲(chǔ)，服務(wù)，無(wú)法統(tǒng)一注入，Scrutor能幫助我們簡(jiǎn)化ASP.NET Core的DI注冊(cè)。

在ConfigServices中，我們?cè)拘枰@樣子依次注入倉(cāng)儲(chǔ)，服務(wù)和其他接口及實(shí)現(xiàn)，當(dāng)有多個(gè)倉(cāng)儲(chǔ)時(shí)，這樣就過于繁瑣。

services.AddTransient<IUserRepository, UserRepository>();
services.AddTransient<IUserService, UserService>();
services.AddTransient<ICurrentUser, CurrentUser>();

Serivce后綴服務(wù)注入DI

當(dāng)我們有多個(gè)Service后綴的服務(wù)時(shí)，使用以下方法，可將服務(wù)掃描只留下以Serivce結(jié)尾的類，將其類型注冊(cè)為提供所有公共接口生成服務(wù)，其生命周期為Transient，

services.Scan(scan => scan
        //加載Startup這個(gè)類所在的程序集
        .FromAssemblyOf<Startup>()
        // 表示要注冊(cè)那些類，上面的代碼還做了過濾，只留下了以 Service 結(jié)尾的類
        .AddClasses(classes => classes.Where(t => t.Name.EndsWith("Service", StringComparison.OrdinalIgnoreCase)))
        //表示將類型注冊(cè)為提供其所有公共接口作為服務(wù)
        .AsImplementedInterfaces()
        //表示注冊(cè)的生命周期為 Transient
        .WithTransientLifetime()
         );

ITransientDependency

新建一個(gè)空接口，當(dāng)其他類繼承此接口后，統(tǒng)一注入到DI中，以Transient的生命周期。

namespace LinCms.Zero.Dependency
{
    public interface ITransientDependency
    {
    }
}

接口

public interface ICurrentUser
{
    int? Id { get; }

    int? GroupId { get; }

    bool? IsAdmin { get; }
}

模擬實(shí)現(xiàn)

    public class CurrentUser : ICurrentUser, ITransientDependency
    {
     
        public int? Id => 1;
        public int? GroupId => 2;
        public bool? IsAdmin => true;
    }

掃描所有繼承ITransientDependency的實(shí)現(xiàn)。

   services.Scan(scan => scan
       // We start out with all types in the assembly of ITransientService
        .FromAssemblyOf<ITransientDependency>()
        // AddClasses starts out with all public, non-abstract types in this assembly.
        // These types are then filtered by the delegate passed to the method.
        // In this case, we filter out only the classes that are assignable to ITransientService.
        .AddClasses(classes => classes.AssignableTo<ITransientDependency>())
        // We then specify what type we want to register these classes as.
        // In this case, we want to register the types as all of its implemented interfaces.
        // So if a type implements 3 interfaces; A, B, C, we'd end up with three separate registrations.
        .AsImplementedInterfaces()
        // And lastly, we specify the lifetime of these registrations.
        .WithTransientLifetime()
         );

如何使用

在其他類中使用此接口

[ApiController]
[Route("cms/user")]
public class UserController : ControllerBase
{
    private readonly ICurrentUser _currentUser;

    public UserController(ICurrentUser currentUser)
    {
        _currentUser = currentUser;
    }

    [HttpGet]
    public int GetUser()
    {
        return _currentUser.Id;
    }
}

統(tǒng)一注入

當(dāng)然，我們可以統(tǒng)一注入，而非寫二次servics.Scan

services.Scan(scan => scan
            .FromAssemblyOf<Startup>()
            .AddClasses(classes => classes.Where(t => t.Name.EndsWith("Service",StringComparison.OrdinalIgnoreCase)))
            .AsImplementedInterfaces()
            .WithTransientLifetime()
            .FromAssemblyOf<ITransientDependency>()
            .AddClasses(classes => classes.AssignableTo<ITransientDependency>())
            .AsImplementedInterfaces()
            .WithTransientLifetime()
      );