Spring AOP Simplifies Logging and Security in Java

📌 Spring Boot Annotation Series Part 17 – @GetMapping The @GetMapping annotation is used to handle HTTP GET requests in Spring Boot applications. It is part of the Spring Framework and is mainly used in REST APIs. 🔹 What is @GetMapping? @GetMapping is a shortcut for: @RequestMapping(method = RequestMethod.GET) Instead of writing the long version, we use this cleaner and more readable annotation. 🔹 Basic Example - @RestController @RequestMapping("/api") public class UserController { @GetMapping("/users") public String getUsers() { return "List of users"; } } 👉 This handles: GET http://localhost:8080/api/users 🔹 When Do We Use GET? ✔ To fetch data ✔ No modification of data ✔ Safe and idempotent operation Example use cases: - Get all users - Get user by ID - Fetch product list - Retrieve order details 🔹 In Simple Words @GetMapping handles read operations in REST APIs. When a GET request hits the URL, Spring executes the mapped method. #SpringBoot #Java #RESTAPI #BackendDevelopment #InterviewPreparation #LearningInPublic

Hi everyone 👋 📌 Spring Boot Annotation Series Part 18 – @PostMapping The @PostMapping annotation is used to handle HTTP POST requests in a Spring Boot application. It is part of the Spring Framework and is mainly used to create new resources in REST APIs. 🔹 What is @PostMapping? @PostMapping is a shortcut for: @RequestMapping(method = RequestMethod.POST) It makes the code cleaner and more readable. 🔹 When Do We Use POST? ✔ To create new data ✔ To submit form data ✔ To send request body (JSON/XML) ✔ When data is modified on the server Example use cases: Create a new user Place an order Register a customer Submit login details 🔹 Basic Example - @RestController @RequestMapping("/api/users") public class UserController { @PostMapping public String createUser(@RequestBody String user) { return "User created: " + user; } } 👉 Handles: POST http://localhost:8080/api/users 🔹 In Simple Words @PostMapping handles create operations in REST APIs. When a POST request hits the URL, Spring executes the mapped method and processes the request body. #SpringBoot #Java #RESTAPI #BackendDevelopment #InterviewPreparation #LearningInPublic

🚀 Build a 𝗛𝗶𝗴𝗵-𝗣𝗲𝗿𝗳𝗼𝗿𝗺𝗮𝗻𝗰𝗲, 𝗧𝗵𝗿𝗲𝗮𝗱-𝗦𝗮𝗳𝗲 Java Logging Framework I designed and implemented a 𝗖𝘂𝘀𝘁𝗼𝗺 𝗝𝗮𝘃𝗮 𝗟𝗼𝗴𝗴𝗶𝗻𝗴 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸 from scratch, focusing on performance, thread safety, and reusability across multiple modules instead of relying on existing logging libraries. The objective was to build a modular, extensible, and thread-safe logging utility that can be reused across Spring Boot applications. 🏗️ Architecture Highlights • 𝗙𝗮𝗰𝘁𝗼𝗿𝘆 𝗣𝗮𝘁𝘁𝗲𝗿𝗻 → Centralized logger creation using LoggerFactory   • 𝗦𝗶𝗻𝗴𝗹𝗲𝘁𝗼𝗻 𝗽𝗲𝗿 𝗖𝗹𝗮𝘀𝘀→ Managed using ConcurrentHashMap<String, CustomLogger>   • Thread-safe initialization using computeIfAbsent()   • 𝗦𝘁𝗿𝗮𝘁𝗲𝗴𝘆 𝗣𝗮𝘁𝘁𝗲𝗿𝗻 → Separate Formatter, Writer, and Level handling   • 𝗣𝗮𝗰𝗸𝗮𝗴𝗲𝗱 𝗮𝘀 𝗿𝗲𝘂𝘀𝗮𝗯𝗹𝗲 𝗝𝗔𝗥 → Plug-and-play across Controller / Service / Repository layers  ⚡ Key Technical Points • 𝗟𝗼𝗰𝗸-𝗳𝗿𝗲𝗲 𝗰𝗼𝗻𝗰𝘂𝗿𝗿𝗲𝗻𝗰𝘆 𝘂𝘀𝗶𝗻𝗴 𝗖𝗼𝗻𝗰𝘂𝗿𝗿𝗲𝗻𝘁𝗛𝗮𝘀𝗵𝗠𝗮𝗽. • One logger instance per class (singleton strategy)   • Multi-module reusable logging library   • Clean separation of concerns following SOLID principles   • Designed for safe usage in multi-threaded environments  🔄 Flow Application Layer   → LoggerFactory   → ConcurrentHashMap Cache   → CustomLogger   → Formatter / Level / Writer   → Console Output The framework is packaged as a reusable library and integrated into a Spring Boot project to simulate real-world multi-layer usage. GitHub: https://lnkd.in/gKpGZrCy This project focuses on practical low-level design, concurrency, and reusable library architecture. #Java #SystemDesign #LowLevelDesign #Concurrency #SpringBoot #DesignPatterns #BackendDevelopment #SoftwareArchitecture

💡 Spring Boot Annotations I Use in Real Projects (With Real-World Use Cases) 🔸Stereotype Annotations (@Component, @Service, @Repository) Structure application into clear layers Controller → Service → Repository Improves maintainability 🔸REST API Annotations (@RestController, @RequestMapping) Build clean, scalable & production-ready REST APIs Simplifies request handling 🔸Configuration & Properties (@Configuration, @ComponentScan, @EnableAutoConfiguration) Reduce manual setup Enable auto-configuration & component scanning 🔸Dependency Injection (@Autowired, @Qualifier, @Inject) Promote loose coupling Improve testability & flexibility 🔸Exception Handling (@ExceptionHandler, @ControllerAdvice) Centralized error handling Clean & consistent API responses 🔸Transaction Management (@Transactional) Automatic commit & rollback Ensures data consistency #spingboot #Java #learning #restapi #webdev

Recently, I stopped “using” Spring Boot and started understanding it. At first, building a REST API felt easy. Controller. Service. Repository. Done. But as the system grew, real engineering problems showed up: Slow endpoints. N+1 queries. Lazy loading errors. Circular dependencies. Bloated service classes. Security confusion with JWT and filter chains. So I stepped back and studied what was actually happening underneath. I read about: • Dependency Injection and Inversion of Control • How JPA and Hibernate generate SQL • Proper transaction boundaries with @Transactional • DTO vs Entity design • Connection pooling and indexing • Clean Architecture principles Then I started applying it. I moved transactions to the service layer. Replaced entity exposure with DTOs. Used fetch joins to fix N+1 queries. Reduced tight coupling by separating responsibilities. Analyzed SQL logs instead of guessing. The biggest lesson: Spring Boot makes it easy to build. But scaling an API forces you to think about design, boundaries, and tradeoffs. Frameworks don’t create clean systems. Engineers do. Still learning. Still refactoring. Still optimizing. #SpringBoot #Java #BackendDevelopment #SoftwareEngineering #CleanArchitecture #SystemDesign #APIDesign #Microservices #Developers

📌 Spring Boot Annotation Series Part 19 – @DeleteMapping @DeleteMapping is used to handle HTTP DELETE requests in a REST API. It is part of Spring Framework and is commonly used in RESTful services built with Spring Boot. 🔹 Why Do We Use @DeleteMapping? In REST APIs: GET → Fetch data POST → Create data PUT → Update data DELETE → Remove data @DeleteMapping handles delete operations. 🔹 What Happens Internally? @DeleteMapping is a shortcut for: @RequestMapping(method = RequestMethod.DELETE) So it is a specialized version of @RequestMapping. 🔹 In Simple Words @DeleteMapping connects an HTTP DELETE request to a controller method to remove a resource. #SpringBoot #Java #RESTAPI #DeleteMapping #BackendDevelopment #InterviewPreparation

Understanding Annotations in Spring Boot: Annotations play a key role in how Spring Boot applications are built and configured. But what exactly are they? Annotations are metadata added to Java code that tell the Spring framework how to behave or configure certain components. Instead of writing large configuration files, Spring Boot uses annotations to simplify development. Some commonly used annotations include: 🔹 @SpringBootApplication Marks the main class and enables auto-configuration, component scanning, and configuration support. 🔹 @RestController / @Controller Used to handle incoming HTTP requests and return responses. 🔹 @Service Indicates that a class contains business logic. 🔹 @Repository Used for database interaction and persistence operations. 🔹 @Autowired Allows Spring to automatically inject dependencies. ✅ These annotations help reduce boilerplate code and make Spring Boot applications easier to build and manage. Understanding how and why annotations are used is an important step toward mastering Spring Boot. #SpringBoot #Java #BackendDevelopment #SoftwareDevelopment

🔹 Concept: Data Validation in Backend APIs In my backend project, I implemented data validation to ensure only correct and meaningful data is stored in the system. 📌 Example validations used: @NotBlank → Ensures the field is not empty @Email → Ensures the email format is valid 📌 Why is validation important? • Prevents invalid or bad data from entering the database • Improves application reliability and data integrity • Helps catch errors early before processing • Enhances API security and stability Proper validation is a critical step in building robust and reliable backend services, especially when developing REST APIs with Spring Boot. #Java #SpringBoot #BackendDevelopment #APIDesign #SoftwareEngineering #Programming #Developers #TechCommunity #JavaDevelopment #CodingJourney

Most teams think multi-tenancy starts with schema design. I think that starts one layer too low. Before multi-tenancy is a database problem, a routing problem, or an isolation problem, it is a context propagation problem. In a real system, tenant identity has to survive the full execution path — controllers, services, repositories, interceptors, async boundaries, and background work — or tenant-aware behavior becomes fragile. That was the core idea behind my latest article: • tenant identity is not just metadata • it is execution context • and if that context is not propagated correctly, multi-tenancy is only partially real One concrete example is pairing a Context Object with a SQLInterceptor. The business code stays generic, while runtime infrastructure applies tenant-aware predicates, schema selection, or routing based on the active tenant context. That gives you a much cleaner model than scattering tenant-specific conditionals across the codebase. The two failure modes are the ones that matter most: • context loss → the system no longer knows which tenant the work belongs to • context leakage → stale tenant context gets reused, which is much worse in production I wrote more about this here: https://lnkd.in/g-VSQGJX #Java #SoftwareArchitecture #Multitenancy #BackendDevelopment #DistributedSystems