How to dynamic ObjectMapper implementation for spring-CodePudding

The client can decide whether the PropertyNamingStrategy is SNAKE_CASE or CAMEL_CASE by adding it to the api parameter.

my idea is to do aop interceptor before entering the controller to customize ObjectMapper.

I have setPropertyNamingStrategy for ObjectMapper object but it only get first PropertyNamingStrategy set, values set after first time are not used.

@Aspect
@Component
@RequiredArgsConstructor
public class NamingJsonAspect {
  private final ObjectMapper objectMapper;

  @Pointcut("execution(public * com.nnv98..*Controller.*(..))")
  private void namingJson() {}

  @SneakyThrows
  @Before("namingJson()")
  public void doAround(JoinPoint proceedingJoinPoint) {
    ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
    assert attributes != null;
    HttpServletRequest request = attributes.getRequest();
    String namingJson = request.getParameter("namingJson");
    if(namingJson.equals("SNAKE_CASE")){
      objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
    }else {
      objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CAMEL_CASE);
    }
  }
}

thank you

CodePudding user response：

You should read the JavaDoc for ObjectMapper.

What you are seeing is expected behavior, as explained in the JavaDoc: configuration can only be done before first read/write usage. After first usage, changing the configuration may have no effect or may result in errors. The JavaDoc also explains how you can work around the limitation.