Java中如何实现全局异常拦截机制

@ControllerAdvice
public class GlobalExceptionHandler {

    // 处理空指针异常
    @ExceptionHandler(NullPointerException.class)
    @ResponseBody
    public ResponseEntity<String> handleNullPointer(NullPointerException e) {
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                .body("发生空指针异常：" + e.getMessage());
    }

    // 处理自定义业务异常
    @ExceptionHandler(BusinessException.class)
    @ResponseBody
    public ResponseEntity<ErrorResponse> handleBusinessException(BusinessException e) {
        ErrorResponse error = new ErrorResponse(e.getCode(), e.getMessage());
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(error);
    }

    // 处理所有未被捕获的异常
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public ResponseEntity<ErrorResponse> handleGeneralException(Exception e) {
        ErrorResponse error = new ErrorResponse("500", "系统内部错误");
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error);
    }
}

public class ErrorResponse {
    private String code;
    private String message;

    public ErrorResponse(String code, String message) {
        this.code = code;
        this.message = message;
    }

    // getter 和 setter 省略
}

public class BusinessException extends RuntimeException {
    private String code;

    public BusinessException(String code, String message) {
        super(message);
        this.code = code;
    }

    // getter 方法
    public String getCode() {
        return code;
    }
}

if (user == null) {
    throw new BusinessException("USER_NOT_FOUND", "用户不存在");
}