.net core three dependency injection methods (native dependency injector, scrutor, autofac)

In .NET Core, Dependency Injection (DI) is a core feature that allows you to manage the life cycle and dependencies of objects in your application. By default, .NET Core provides a built-in DI container, but you can also choose to extend it, or use third-party DI frameworks such as Scrutor and Autofac. Below I will introduce the advantages and disadvantages of these three methods and help you understand their respective characteristics.

1. Native .NET Core dependency injection container

.NET Core provides a lightweight dependency injection container by default, commonly known as. This is an out-of-the-box solution for most simple and moderately complex applications.

Main features

• Built-in support: No additional libraries are required, use them directlyThe Core project is OK.
• Easy to use: The dependency injection API is very simple and suitable for basic DI usage scenarios.
• Support basic life cycle: supportTransient、ScopedandSingletonThree life cycle management methods.
• Limited features: Not supported some advanced features, such as conditional registration, automatic registration, scanning classes according to conventions, etc.

Example of usage

public void ConfigureServices(IServiceCollection services) {     
    <IServiceA, ServiceA>(); // Transient life cycle    <IServiceB, ServiceB>(); // Scoped life cycle    <IServiceC, ServiceC>(); // Singleton life cycle}

advantage

• High integration: highly integrated with frameworks such as Core.
• Performance: Since it is a lightweight container, it performs better.
• Low learning curve: No additional learning and configuration is required, suitable for most common scenarios.

shortcoming

• Limited functions: advanced functions such as automatic scanning and registration according to agreements are not supported, and the API is relatively basic.
• Poor scalability: If you need more advanced features, you may need to implement many functions yourself, or introduce third-party libraries.

2. Native .NET Core Dependency Injection Container + Scrutor

Scrutor is an open source library used to extend the built-in DI container of .NET Core, providing automatic registration, scanning classes according to conventions, conditional registration and other functions. It allows you to enjoy more automation and flexibility based on using native dependency injection containers.

Main features

• Automatic scanning and registration: Scrutor supports automatic scanning of assemblies and registration according to conventions such as namespace, class suffix, etc., reducing the workload of manual registration.
• Flexible service registration: Services can be registered dynamically based on different conditions (for example, select services based on configuration or environment).
• More richer features: chain calls and custom registration behavior, such as registering by class name suffix or adding interceptors to services.

Example of usage

public void ConfigureServices(IServiceCollection services) { 
    (scan => scan .FromAssemblyOf<Startup>() // Scan the assembly    .AddClasses(classes => <Startup>()) // Select the class by namespace    .AsImplementedInterfaces() // Register as an implementation interface    .WithTransientLifetime()); // Use Transient Lifecycle}

advantage

• Automation: Automatically register classes and interfaces, avoiding the lengthy manual registration process, especially suitable for large projects.
• Strong flexibility: supports registration according to agreements, conditions and rules, allowing services to be managed more efficiently.
• Scalability: Added a lot of features to native containers, allowing developers to configure dependency injection more flexibly.

shortcoming

• Introducing additional libraries: The additional Scrutor library is required.
• It may have a small impact on performance: automatic scanning and registration can bring some performance overhead, especially in large applications.

3. Use Autofac

Autofac is a popular third-party dependency injection framework that provides richer features than .NET Core's built-in containers. It supports complex service life cycles, conditional registration, modular registration and other advanced functions, and is one of the commonly used third-party DI frameworks in .NET Core development.

Main features

• Advanced features: such as conditional injection, attribute injection, modular registration, and more fine-grained dependency resolution, etc., suitable for more complex scenarios.
• Scalability and flexibility: Provides rich scaling mechanisms that can adjust DI behavior as needed, for example throughModuleCome to register services in batches, or realize your ownIServiceProvider。
• Performance optimization: For large-scale applications, Autofac has better performance and management capabilities and can provide more control and optimization.

Example of usage

public void ConfigureServices(IServiceCollection services) { 
    var builder = new ContainerBuilder(); 
    // Register service    <ServiceA>().As<IServiceA>().InstancePerDependency(); // Transient life cycle    <ServiceB>().As<IServiceB>().SingleInstance(); // Singleton life cycle    
    // Add existing services to Autofac container    (services);  

    // Build the container and use it    var container = (); 
    return new AutofacServiceProvider(container); 
}

advantage

• Rich functions: Support complex scenarios such as conditional injection, attribute injection, dynamic service generation, modular registration, etc.
• Strong scalability: Provides many custom hooks and expansion points, allowing for very flexible customization of DI behavior.
• Performance: For complex applications, Autofac provides better performance optimization and service management capabilities.

shortcoming

• Steeper learning curve: Autofac offers more configuration and extension options than native dependency injection containers, which may take more time to learn and master.
• Additional dependencies: third-party libraries (Autofac) need to be introduced to increase the complexity of the project.

Summary and comparison

• Native .NET Core DI is suitable for small and medium-sized applications, especially when functional requirements are relatively simple.
• Native DI + Scrutor is suitable for medium to large applications, especially when automatic scanning, conventional registration and flexible configuration are required.
• Autofac is suitable for large and complex applications, especially scenarios that require more customization and flexibility.

Depending on your project size, requirements complexity and team experience, it is important to choose the right dependency injection method.

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