Spring Boot Global Exception Handling with @RestControllerAdvice

🤔 Why your transaction COMMITs even after throwing an exception This is a trap many Spring developers fall into. By default, Spring rolls back transactions only for runtime exceptions. @Transactional public void processOrder() throws Exception { throw new Exception("failed"); } Looks correct. But the transaction commits. Why? Because checked exceptions do NOT trigger rollback by default. So you get: Exception thrown API fails But DB data is still saved To fix it: @Transactional(rollbackFor = Exception.class) This behavior has caused real production bugs. If you’re using @Transactional, this worth remembering ❗ #springboot #transactions #java #backend

Day 19 – Exception Handling in Spring Boot Today I focused on handling exceptions properly in Spring Boot applications. Exception handling is important for building reliable and production-ready APIs. Instead of exposing raw errors, we should return meaningful and structured responses. =>@ControllerAdvice Used to handle exceptions globally across the entire application. It allows centralized error handling instead of writing try-catch blocks in every controller. =>@ExceptionHandler Used to handle specific exceptions. It defines what response should be returned when a particular exception occurs. => Custom Exceptions Creating custom exception classes improves clarity. For example, throwing a ResourceNotFoundException when data is not found makes the API more meaningful. => Proper exception handling improves: Code cleanliness User-friendly error responses Maintainability API reliability Structured exception handling is essential for building production-ready and maintainable backend systems. #Day19 #SpringBoot #ExceptionHandling #Java #BackendDevelopment #LearningJourney

APIs Are Contracts, Not Just Endpoints Once an API is public: fields shouldn’t disappear behavior shouldn’t change silently Backward compatibility is a backend responsibility. #Java #RESTAPI #SystemDesign

🚀 Mastering Spring Boot (Spring Bean) Recently, I explored Java-based configuration in Spring Boot and how beans are managed using the IoC container. Key takeaways: 1️⃣ What is a Spring Bean? A Spring Bean is an object managed by the Spring IoC container. Spring creates, configures, and manages its lifecycle. Beans are usually defined using @Component, @Service, @Repository, or @Bean in a @Configuration class. The container handles dependency injection, so you don’t need to manually new the object. ✅ Cleaner, maintainable, and scalable code 💡 Pro Tip: Using @Configuration & @Bean effectively gives you full control over your beans and is a must-know for building robust Spring Boot applications. #SpringBoot #Java #IoC #ApplicationContext #DependencyInjection #JavaConfig #SpringFramework #CleanCode #EnterpriseJava

Application Starts ↓ Spring IoC Container Created ↓ Spring Context Initialized ↓ Beans Created & Managed ↓ Dependencies Injected (DI) ↓ Bean Lifecycle Managed ↓ Application Uses Beans ↓ Context Closed → Beans Destroyed This learning helped me understand how Spring Boot builds loosely coupled, scalable, and maintainable backend applications. #SpringBoot #Java #BackendDevelopment #LearningJourney #SpringFramework #Developer #JavaDeveloper

What is the difference between @ComponentScan and @EnableAutoConfiguration in Spring Boot? 🎯 @ComponentScan finds and registers your classes annotated with: @Component, @Service, @Repository, @Controller (from the package where your main class exists and its sub-packages) 🎯 @EnableAutoConfiguration automatically configures Spring Boot beans based on: dependencies present in the classpath application properties 🎯 Example If you add spring-boot-starter-web, @EnableAutoConfiguration automatically configures things like: embedded Tomcat DispatcherServlet JSON converter And @ComponentScan will detect your UserController, UserService, etc. ------------------------------------------------------------------- Conclusion @ComponentScan = find my code beans @EnableAutoConfiguration = configure framework beans automatically ✅ #SpringBoot #Java #Microservices #BackendDevelopment #SpringFramework #AutoConfiguration #ComponentScan #SoftwareEngineering #InterviewPreparation #JavaDeveloper #RestAPI #TechInterview #CleanCode #DeveloperLife

Day 17 – Spring Boot Annotations Explained Today I focused on understanding some important Spring Boot annotations that power backend applications. -> @RestController Combines @Controller and @ResponseBody. It is used to create REST APIs and return JSON responses directly. -> @RequestMapping Maps HTTP requests to specific handler methods. It defines the URL path and supports different HTTP methods like GET, POST, PUT, and DELETE. -> @Autowired Used for Dependency Injection. Spring automatically injects required beans into a class. -> @Configuration Indicates that a class contains bean definitions. Spring processes it to generate and manage beans in the application context. Understanding these annotations helps in writing clean, structured, and maintainable backend code. Spring Boot reduces complexity, but knowing what happens behind the scenes makes a real difference. #Day17 #SpringBoot #Java #BackendDevelopment #Annotations #LearningJourney

❓Did you know your Spring Boot controller might never run? With @Valid, validation happens before your method executes. If input is wrong, Spring stops the request at the door. I broke down what really happens in the validation flow — and why it matters in real APIs. 📖 https://lnkd.in/d2sZmuPH #SpringBoot #Java #BackendDevelopment #RESTAPI #SoftwareEngineering

💡 Ever faced an API that “works”… but feels messy inside? Here’s a small but powerful Spring Boot REST API practice I learned the hard way 👇 - Always return a ResponseEntity\<T\> instead of plain objects. It gives you full control over HTTP status codes and response metadata. - Add a GlobalExceptionHandler using @ControllerAdvic — it keeps your error handling clean and consistent. - Never expose JPA entities directly! Use DTOs to avoid lazy-loading traps and improve security. These tweaks might look small, but they make your APIs feel enterprise-grade. 🚀 👉 What’s one Spring Boot tip you wish you knew earlier? #Java #SpringBoot #FullStackDeveloper #RESTAPI #CodingLife #BackendDevelopment

🚨 Spring Boot, @Bean inside @Component behaves VERY differently Look at this: @Component public class AppConfig {   @Bean   public OrderService orderService() {     return new OrderService();   } } Looks fine, right? ❌ But this does NOT behave like @Configuration. 🧠 What actually happens at runtime When @Bean is inside @Component: ❌ No CGLIB proxy ❌ No method interception ❌ No singleton guarantee on method calls Calling: orderService(); orderService(); 👉 creates NEW objects every time This mode is called Lite Configuration. ✅ Correct way (Full Configuration Mode) @Configuration public class AppConfig {   @Bean   public OrderService orderService() {     return new OrderService();   } } Here Spring: Creates a CGLIB proxy Intercepts method calls Always returns the same singleton bean 🚨 Why this matters in real projects @Bean public PaymentService paymentService() {   return new PaymentService(orderService()); // 💥 different instance } ➡ Silent bugs ➡ Unexpected behavior ➡ Painful production debugging No exception. No warning. Just wrong behavior. 🎯 Golden Rule @Configuration changes how Java methods behave. @Component does not. #SpringBoot #Java #SpringFramework #Backend #SoftwareEngineering #JVM #SpringTips