Spring Boot: Use ThreadLocal-variable or pass parameters

Question

I´m wondering what is best practice with spring-boot and the already provided helper-classes that use ThreadLocal for saving values suche as LocaleContextHolder or RequestContextHolder.

Actually I do not really like to pass parameters such as Request or Locale through every method call and blows up the signature until it is finally used. I would rather like to hide this information-details and obtain the required information where necessary within the service. But is the RequestContextHolder or LocaleContextHolder the right thing to use then or is it bad habbit to rely on ThreadLocal operations? What is a recommended approach?

What problems might occur when relying on ThreadLocal? I read about cleaning-up is an important thing, but as this is done already by spring-boot I would assume these are safe operations.

Thanks for your input

Answer 1

If you want to access request-dependent objects like Locale or Request and do not want to blow up your method's signature with additional paramters you can access them using static methods provided by RequestContextHolder or LocaleContextHolder.

Example:

public String getLocaleOfRequest(){
    return LocaleContextHolder.getLocale()
}

There is actually no need to define ThreadLocals in your code for it.