Building an IoC Container from Scratch with .NET Framework 4.7.2

This article dissects the core mechanisms of dependency injection by manually implementing a minimalist IoC container. The author points out that IoC primarily consists of three elements: registration, resolution, and lifecycle management. The article presents implementation code based on C# reflection and dictionary mapping, with a focus on analyzing how the Resolve method recursively searches for constructor parameters and automatically creates dependency instances, thereby solving the cumbersome problem of manually assembling objects. Through a test case involving a three-level dependency chain, the article verifies that the container can automatically populate constructor parameters and correctly implements the singleton pattern, ensuring that the same service instance is returned during multiple resolutions. The author also notes that although this simplified container lacks enterprise-grade features such as Scoped lifecycle, thread-safe locking, circular dependency detection, and IDisposable resource management, its 50-plus lines of code precisely reveal the essence of an IoC container: achieving inversion of control by recursively resolving the dependency tree and building objects layer by layer from the leaf nodes upward.