Annotations

Spring Boot is a popular framework for building Java-based enterprise applications, including RESTful APIs. Annotations play a crucial role in Spring Boot applications, as they help define the behavior of various components. Here are some common annotations used for creating RESTful APIs in Spring Boot:

1. @SpringBootApplication:

   • Usage: Main class of the Spring Boot application. It is often placed on the class containing the main method.

   • Example:

     @SpringBootApplication
     public class MyApplication {
         public static void main(String[] args) {
             SpringApplication.run(MyApplication.class, args);
         }
     }

2. @RestController:

   • Usage: Applied to classes to indicate that they are controllers handling HTTP requests and responses.

   • Example:

     @RestController
     public class MyController {
         // Controller methods here
     }

3. @RequestMapping (or @GetMapping, @PostMapping, @PutMapping, @DeleteMapping):

   • Usage: Used to map HTTP requests to specific handler methods.

   • Example:

     @RestController
     public class MyController {
         @GetMapping("/hello")
         public String sayHello() {
             return "Hello, World!";
         }
     }

4. @PathVariable:

   • Usage: Extracts values from URI templates in @RequestMapping annotated methods.

   • Example:

     @GetMapping("/hello/{name}")
     public String sayHello(@PathVariable String name) {
         return "Hello, " + name + "!";
     }

5. @RequestParam:

   • Usage: Binds parameters from the query string to the method parameters.

   • Example:

     @GetMapping("/greet")
     public String greet(@RequestParam String name) {
         return "Greetings, " + name + "!";
     }

6. @RequestBody:

   • Usage: Used to bind the HTTP request body to a method parameter.

   • Example:

     @PostMapping("/create")
     public ResponseEntity<String> create(@RequestBody MyEntity entity) {
         // Process the entity and return a response
     }

7. @ResponseStatus:

   • Usage: Sets the HTTP status code for the response.

   • Example:

     @PostMapping("/create")
     @ResponseStatus(HttpStatus.CREATED)
     public ResponseEntity<String> create(@RequestBody MyEntity entity) {
         // Process the entity and return a response
     }

8. @CrossOrigin:

   • Usage: Configures Cross-Origin Resource Sharing (CORS) for a controller or a specific method.

   • Example:

     @CrossOrigin(origins = "http://localhost:8080")
     @RestController
     public class MyController {
         // Controller methods here
     }

Depending on your application's requirements, you may need to use additional annotations or customize the behavior of these annotations further.