Introduction to the Spring Framework: IOC, AOP, and Building a Spring Web Application

Spring is an open‑source Java platform that provides a comprehensive infrastructure for quickly building durable applications; it simplifies web project setup and serves as the foundation for many enterprise solutions.

The core of Spring consists of the IOC container and AOP support. IOC (Inversion of Control) delegates object creation and dependency wiring to the container, typically configured via XML or Java annotations. AOP (Aspect‑Oriented Programming) allows cross‑cutting concerns such as logging, performance monitoring, and exception handling to be modularized using aspects, pointcuts, and advice.

To demonstrate these concepts, a Spring Boot web project is used. The project follows a five‑module structure: view, controller, service, model, and AOP. The @Controller annotation registers a controller class in the IOC container, while @Autowired injects a UserService implementation automatically. The service layer is marked with @Service , enabling the container to instantiate and inject it wherever needed.

In the aop package, a LogAspect class defines a pointcut that matches all public methods in the demo.controller package. @Before and @AfterReturning advice log method parameters and return values, illustrating how AOP can transparently add behavior without modifying business code.

The main class ( WebApplication ) contains a single SpringApplication.run() call, which boots the embedded Tomcat server, initializes the IOC container, scans for annotated components, and starts the web application on port 8080.

When a user accesses /users , the UserController handles the request, delegates to UserService for data retrieval, and returns a view name. Thymeleaf renders the view template with the model data. Creating a new user follows a similar flow: a POST request triggers a service method that persists the entity, then redirects back to the user list.

The article also includes promotional notes encouraging readers to join a WeChat architecture community for additional resources, but the technical content remains focused on Spring fundamentals and practical web development.