About Audit

 Audit is a very popular feature, and every company I worked with implementing auditing in a different way. Other than JPA audit and using PLSQL trigger, I have done an audit event service which reading message from Message Queue and persist into DB, and also implement @Auditable using spring AOP. My current company prefers to use spring event to achieve the same goal, it's similar to the event service I built.

@Getter
@Setter
@ToString
@EqualsAndHashCode
public class AuditEvent extends ApplicationEvent{
    private AuditType auditType;
    private BaseEntity entity;
    private String oldValue;
    private String newValue;
    private String moduleId;
    private String sourceIp;
    private String dataName;
}

@Component
@RequiredArgsConstructor
public class AuditPublisher{
    final ApplicationEventPublisher publisher;

    public void publishAudit(AuditEvent auditEvent) {
        publisher.publishEvent(auditEvent);
    }
}

@Service
public class SomeService{
    private final AuditPublisher auditPublisher;

    public void createSomething(){
        AuditEvent auditEvent = new AuditEvent();
        auditPublisher.publishAudit(auditEvent);
    }
}

@Component
public class AuditListener implements ApplicationListener<AuditEvent> {
    final AuditTrailRepository auditTrailRepository;

    public void onApplicationEvent(AuditEvent auditEvent) {
        AuditTrail auditTrail = AuditTrail.builder().build();

        BeanUtils.copyProperties(auditEvent, auditTrail);
        auditTrail.setCreatedBy(AuditContext.getCurrentUser);
        auditTrailRepository.save(auditTrail);
    }
}

@Component
public class AuditInterceptor implements WebRequestInterceptor {
    public void preHandle(WebRequest request) {
        String username = null;
        if (request.getHeader("User") != null) {
            username = request.getHeader("User");
        }
        AuditContext.setCurrentUser(username);
    }

    public void postHandle(WebRequest request, ModelMap modelMap) {
        AuditContext.clear();
    }
}

public final class AuditContext {
    private static final InheritableThreadLocal<String> CURRENT_USER = new InheritableThreadLocal<>();
    private AuditContext() {
        
    }

    public static void setCurrentUser(String username) {
        CURRENT_USER.set(username);
    }
    
    public static String getCurrentUser(){
        return CURRENT_USER.get();
    }
    
    public static void clear(){
        CURRENT_USER.remove();
    }
}