Java REST API的泛型

@RestController
@RequestMapping("/api")
public class GenericController {

    @GetMapping("/first")
    public <T> T getFirstElement(@RequestParam List<T> list) {
        return getFirstElement(list);
    }

    private <T> T getFirstElement(List<T> list) {
        if (list == null || list.isEmpty()) {
            return null;
        }
        return list.get(0);
    }

    @PostMapping("/box")
    public ResponseEntity<ApiResponse<Box<String>>> createBox(@RequestBody Box<String> box) {
        ApiResponse<Box<String>> response = new ApiResponse<>();
        response.setStatus(200);
        response.setMessage("Box created successfully");
        response.setData(box);
        return ResponseEntity.ok(response);
    }
}

class Box<T> {
    private T value;

    public Box(T value) {
        this.value = value;
    }

    public T getValue() {
        return value;
    }

    public void setValue(T value) {
        this.value = value;
    }
}

class ApiResponse<T> {
    private int status;
    private String message;
    private T data;

    // getters and setters
}