Spring Boot
Request & Response Handling
Handle HTTP requests and build proper API responses.
@RequestBody and @ResponseBody
@RequestBody: Binds the HTTP request body to a Java object (for POST/PUT)
@ResponseBody: Writes the return value to the HTTP response body (included in @RestController)
Java
@PostMapping("/users")
public ResponseEntity<UserDto> createUser(@RequestBody @Valid UserDto dto) {
UserDto created = userService.create(dto);
URI location = URI.create("/api/users/" + created.getId());
return ResponseEntity.created(location).body(created);
}Query Parameters and Path Variables
Extract values from the URL:
Java
// Path Variable: /api/users/42
@GetMapping("/{id}")
public User getUser(@PathVariable("id") Long userId) { ... }
// Query Param: /api/users?page=0&size=10
@GetMapping
public Page<User> getUsers(
@RequestParam(defaultValue = "0") int page,
@RequestParam(defaultValue = "10") int size) { ... }