Hi,
take a look at
https://ci.apache.org/projects/wicket/guide/8.x/single.html#_components_lifecycle
You might want to move the code from constructor to
onInitialize()
and you can use
onRemove()
to free it up as this is called when the component gets removed from the page /
the page itself gets removed;
Keep in mind that wicket stores old pages by default. In your case you might
also want to have a look at LoadableDetachableModel, so that the model can
react with "activation"/"passivation" of its data;
The goal should usually be to not store any data at all that can be retrieved,
so to not waste memory - said, it might be necessary in your case to store it
with the page as it might be very expensive to (re)create the data, then the
above onInitialize/ onRemove on the page level would be good to use;
Best,
KB
----- Ursprüngliche Mail -----
> Von: "yvus" <yves.courvois...@enata.com>
> An: users@wicket.apache.org
> Gesendet: Dienstag, 25. September 2018 11:22:15
> Betreff: Demo Page with User Related Data
> Dear All,
>
> I have the complex task to develop a webpage GUI for a java/c++ app, i.e.
> the java app contains objects that wrap c++ classes of a .so library. For
> example the Frame.java class wraps a corresponding c++ class frame.h (which
> does the math). Therefore we call in the constructor of the Frame.java class
> a c++ constructor through JNA and store the Pointer in a field.
>
> public class Frame {
> private Pointer cppPointer;
> public Frame() {
> cppPointer = Wrapper.INSTANCE.frameConstructor(...) // JNA call to
> c++ constructor retrieving the c++ pointer.
> }
> }
>
> On the webpage, I have the following scenario in which we display a demo
> page which renders a 3d view. The user is able to displace an object which
> position is determined by the fields of Frame.java and hence the c++
> classes. Moving the object is done by changing 'values' in a form. Each of
> these 'values' directly modify the Frames and hence the Frame c++-class's
> attributes.
>
> In order to have the pointers created only once per page, we construct all
> the pointers in the constructor of the page and store them in a model which
> serializes the addresses. This allows to have the c++ side created only once
> on the page. This seems fine until we have to destroy the pointers memory.
>
> How to determine when we leave the page in order to destroy the Pointers?
> How would you manage this scenario? is it a good thing to construct the
> pointers in the constructors of the page? When would you allow to destroy
> the c++ allocated memory?
>
> Thanks
>
> --
> Sent from:
> http://apache-wicket.1842946.n4.nabble.com/Users-forum-f1842947.html
>
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