CODEWITHSUNDEEP
javaxmlserializationjaxbxml-serialization
Arturas M
Arturas M

Reputation: 4369

How to implement an xml saveable/loadable class?

I would like to create a class, which would be loadable and saveable to an XML file. I want to use one class which is doing the loading task and I want to integrate it with the actual class that I want to save and load, everything seems to be doable up to the point where JAVA doesn't allow the class instance to be change from within the class, i.e. there is no:

this = JAXBLoader.load();

So currently that's the problem I'm facing.

And I want to be able to control the loading and saving it via the public methods from the class itself, so that from the outside I don't need any factories or managers to load it. Currently the only solution I've seen to this was if I extended the class that I want to save as an xml and then delegate all the methods to the intance of the actual class and then when loading a new instance from the file, the instance would get replaced. But it is a bit of overhead to have to delegate all of the methods, especially pain in the ass if you need to add new methods to the class and have multiple implementations...

So are there any good practices or patterns on achieving something similar or solving the problem I demonstrated above? Actually I'm open, if somebody can overall share what are the best ways to do class saving and loading the easiest ways I would really glad about it.

Upvotes: 0

Views: 70

Answers (1)

lexicore
lexicore

Reputation: 43671

I'm not quite sure why do you want to avoid external factories and managers. For me it seems quite natural to extract serialization and not handle it in the model classes themselves. But okay.

What I understood is that your core problem is to load data into this instance. Here's a simple way to achieve this with JAXB.

I'm the author of JAXB2 Basics, a plugin package for JAXB/XJC. It contains the copyable plugin which generates a few copyTo methods in the schema-derived classes.

This will give you methods like copyTo(Object target). With this you can first unmarshal data from XML into some temporary instance and then copyTo(this). Something like:

MyType temporaryInstance = unmarshaller.unmarshal(source, MyType.class).getValue();
temporaryInstance.copyTo(this);

You can add this method to your schema-derived code via code injection or by subclassing.

Upvotes: 1

Related Questions