Database Aspect

DatabaseAspect.java

@Aspect
@Component
public class DatabaseAspect {
    /**
     * AOP joint point handler that will be invoked by AOP when it encounters a method annotated with Database
     * or the class containing this method is annotated with Database.
     *
     * @param jointPoint joint point object
     * @return the result of joint point
     * @throws Throwable if any exception occurred while handling joint point
     */
    @Around("@within(Database) || @annotation(Database)")
    public Object database(ProceedingJoinPoint jointPoint) throws Throwable {
        MethodSignature signature = (MethodSignature) jointPoint.getSignature();
        Method method = signature.getMethod();
        String name = findDatabaseName(method).orElse("");
        try {
            DatabaseContext.set(name);
            return jointPoint.proceed();
        } finally {
            DatabaseContext.clear();
        }
    }

    /**
     * findDatabaseName finds the database name for this method, the method or class declaring
     * this method would have Database annotation. We try to first find the annotation from the method
     * if method does not contain the annotation than we check class if that contains any annotation.
     *
     * @param method method object
     * @return an optional string
     */

    private Optional<String> findDatabaseName(Method method) {
        // the performance of this can be improved by caching the result in a map
        Database database = Optional.ofNullable(method.getAnnotation(Database.class)).orElseGet(() -> {
            Class<?> klass = method.getDeclaringClass();
            return AnnotationUtils.findAnnotation(klass, Database.class);
        });
        return Optional.ofNullable(database).map(Database::value);
    }
}