Abhimanyu Mishra’s Post

Understanding Key Annotations in Spring Boot Annotations make Spring Boot development simple and powerful. Let’s look at three important ones 👇 🔹 @Entity → Represents a table in the database → Each instance of the class maps to a row → Used in the data layer 🔹 @RestController → Handles HTTP requests and returns responses → Used to build REST APIs → Combines @Controller + @ResponseBody 🔹 @Service → Contains business logic of the application → Acts as a bridge between Controller and Repository ✅ In simple terms: • @RestController → Handles requests • @Service → Processes logic • @Entity → Represents data Understanding these annotations helps you see how different layers in Spring Boot work together. #SpringBoot #Java #BackendDevelopment #LearningInPublic #DeveloperGrowth

When working with APIs, you often need to pass data in the request. Spring Boot provides two common ways: @PathVariable and @RequestParam Example: @GetMapping("/users/{id}") public String getUser(@PathVariable int id) { return "User ID: " + id; } Here, id is part of the URL. Now using RequestParam: @GetMapping("/users") public String getUser(@RequestParam int id) { return "User ID: " + id; } Difference: • @PathVariable → part of URL path • @RequestParam → query parameter Example URLs: /users/10 → PathVariable /users?id=10 → RequestParam Choosing the right one improves API design. Next post: What is @RequestBody and how JSON is handled #Java #SpringBoot #BackendDevelopment #APIDesign

New to Spring Boot? You'll see these annotations in every project. Here's what they actually do: @SpringBootApplication → Entry point. Combines @Configuration, @EnableAutoConfiguration, @ComponentScan @RestController → Marks a class as an HTTP request handler that returns data (not views) @Service → Business logic layer. Spring manages it as a bean @Repository → Data access layer. Also enables Spring's exception translation @Autowired → Inject a dependency automatically (prefer constructor injection instead) @GetMapping / @PostMapping / @PutMapping / @DeleteMapping → Maps HTTP methods to your handler methods @RequestBody → Deserializes JSON from request body into a Java object @PathVariable → Extracts values from the URL path Bookmark this. You'll refer back to it constantly. Which annotation confused you the most when starting out? 👇 #Java #SpringBoot #Annotations #BackendDevelopment #LearningInPublic

@Service in Spring Boot @Service is used to define the business logic layer in a Spring Boot application. It tells Spring: “This class contains the core logic of the application.” Key idea: • Processes data • Applies business rules • Connects Controller and Repository Works closely with: • @Repository → Fetches data • @RestController → Handles requests In simple terms: @Service → Handles Logic Understanding @Service helps you keep your application clean, organized, and maintainable. #SpringBoot #Java #BackendDevelopment #LearningInPublic

#Java #Spring #Bean 🌱 Spring Bean Lifecycle 👉 In Spring Framework, bean lifecycle has 5 simple steps: 🔄 Lifecycle Steps 1️⃣ Instantiate ➡️ Spring creates object 2️⃣ Inject Dependencies 💉 ➡️ Dependencies added (@Autowired) 3️⃣ Initialize ⚙️ ➡️ Setup using @PostConstruct 4️⃣ Use Bean 🚀 ➡️ Business logic runs 5️⃣ Destroy 🧨 ➡️ Cleanup using @PreDestroy 🧠 One-Line 👉 Spring Bean Lifecycle = Create → Inject → Initialize → Use → Destroy (managed by Spring Container)

#Post3 In the previous post, we understood the role of @RestController in building APIs. Now the next step is 👇 How do we map HTTP requests to methods? That’s where mapping annotations come in 🔥 In Spring Boot, we use: • @GetMapping → for GET requests • @PostMapping → for POST requests • @PutMapping → for UPDATE • @DeleteMapping → for DELETE • @PatchMapping → for partial updates Example: @GetMapping("/users") → fetch all users @PostMapping("/users") → create a new user 💡 What about @RequestMapping? @RequestMapping is a generic annotation that can handle all HTTP methods. Example: @RequestMapping(value="/users", method=RequestMethod.GET) 👉 But in modern Spring Boot, we prefer specific annotations like @GetMapping for cleaner and readable code Key takeaway: Use specific mapping annotations for better clarity and maintainability 👍 In the next post, we will understand how @RequestBody works in handling request data 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic

🚀 Spring Boot — Why I stopped using Entity in request body Earlier, I used to accept Entity directly in my APIs: @PostMapping("/users") public User createUser(@RequestBody User user) { return userService.save(user); } It worked… but later I realized the problem. ⸻ Issues I faced: ✔ Unnecessary fields coming from request ✔ Hard to control what client sends ✔ Tight coupling with DB structure What I do now: Use DTO instead: @PostMapping("/users") public User createUser(@RequestBody UserDto dto) { return userService.create(dto); } ✔ Only required fields ✔ Better validation ✔ Cleaner API contract ⸻ ⭐ Simple rule: 👉 Entity → database 👉 DTO → request/response Small change, but made APIs much safer. Do you accept Entity or DTO in your request body? #SpringBoot #JavaDeveloper #BackendDevelopment #LearningInPublic #Java

How Spring Boot Handles Requests Internally (Deep Dive) Ever wondered what happens when you hit an API in Spring Boot? 🤔 Here’s the real flow 👇 🔹 DispatcherServlet Acts as the front controller receives all incoming requests 🔹 Handler Mapping Maps the request to the correct controller method 🔹 Controller Layer Handles request & sends response 🔹 Service Layer Contains business logic 🔹 Repository Layer Interacts with database using JPA/Hibernate 🔹 Response Handling Spring converts response into JSON using Jackson 🔹 Exception Handling Handled globally using @ControllerAdvice 💡 Understanding this flow helped me debug issues faster and design better APIs. #Java #SpringBoot #BackendDeveloper #Microservices #RESTAPI #FullStackDeveloper #LearningInPublic

Clean REST API in Spring Boot (Best Practice) 🚀 Here’s a simple structure you should follow 👇 📁 Controller - Handles HTTP requests 📁 Service - Business logic 📁 Repository - Database interaction Example 👇 @RestController @RequestMapping("/users") public class UserController { @Autowired private UserService userService; @GetMapping("/{id}") public User getUser(@PathVariable Long id) { return userService.getUserById(id); } } 💡 Why this matters: ✔ Clean code ✔ Easy testing ✔ Better scalability ⚠️ Avoid: Putting everything inside controller ❌ Structure matters more than code 🔥 Follow for more practical backend tips 🚀 #SpringBoot #Java #CleanArchitecture #Backend

🚀 Developed a basic REST API using Spring Boot to handle HTTP requests and responses. 🔹 What I implemented: Created a REST Controller using @RestController Used @RequestMapping to define base URL (/api) Built a GET API using @GetMapping("/student") 🔹 API Endpoint: http://localhost:8080/api/student 🔹 Output: "Student data" 🔹 Key Learnings: How Spring Boot handles HTTP requests Understanding request → controller → response flow Basics of REST API development Excited to move next into POST APIs and sending real data using @RequestBody 🔥 #SpringBoot #Java #BackendDevelopment #LearningJourney #CSE