What is Spring Boot?
Answer:
Spring Boot is a framework built on top of Spring that simplifies the development of Java applications by reducing configuration and setup time.
Key Features:
- Auto-configuration
- Embedded server (Tomcat)
- Production-ready features
- Minimal configuration
Why use Spring Boot?
Answer:
Spring Boot is used to quickly build stand-alone and production-ready applications with less boilerplate code.
Benefits:
- Faster development
- Easy deployment
- No need for XML configuration
- Microservices friendly
What is a REST API?
Answer:
REST (Representational State Transfer) API is a web service that allows communication between client and server using HTTP methods.
HTTP Methods:
- GET → Fetch data
- POST → Create data
- PUT → Update data
- DELETE → Remove data
What is @RestController?
Answer:
@RestController is a combination of @Controller and @ResponseBody. It is used to create RESTful web services.
Example:
“`java id=”r1″
@RestController
@RequestMapping(“/api”)
public class MyController {
@GetMapping("/hello")
public String hello() {
return "Hello World";
}}
---
## What is @RequestMapping?
### Answer:
@RequestMapping is used to map HTTP requests to handler methods in a controller.
### Example:java id=”r2″
@RequestMapping(value = “/test”, method = RequestMethod.GET)
public String test() {
return “Test API”;
}
---
## What is @Autowired?
### Answer:
@Autowired is used for dependency injection. It automatically injects required beans.
---
## What is Dependency Injection?
### Answer:
Dependency Injection is a design pattern where objects are provided to a class instead of creating them inside the class.
---
## What is Spring Boot Starter?
### Answer:
Spring Boot starters are pre-configured dependencies that simplify project setup.
### Example:
* spring-boot-starter-web
* spring-boot-starter-data-jpa
---
## What is Exception Handling in Spring Boot?
### Answer:
Spring Boot provides @ControllerAdvice and @ExceptionHandler to handle exceptions globally.
### Example:java id=”r3″
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(Exception.class)
public String handleException() {
return "Error occurred";
}}
---
## What is JWT (JSON Web Token)?
### Answer:
JWT is a token-based authentication mechanism used to securely transmit information between client and server.
---
## JWT Flow:
1. User logs in
2. Server generates JWT token
3. Client stores token
4. Client sends token in header
5. Server validates token
---
## JWT Example (Header)java id=”r4″
Authorization: Bearer
“`
Advantages of JWT:
- Stateless authentication
- Secure
- Scalable for microservices
Interview Tip:
Always explain with:
✔ Definition
✔ Real-world use
✔ Code example