Relax MyBatisPagingItemReader to allow constructor instanciation

[MadJlzz]

This PR is linked to the issue #323

Basically, I used the SqlSession interface instead of the SqlSessionTemplate implementation.

I override doOpen() and doClose() to avoid initialization of the connection through afterPropertiesSet.

This is not a final version ready to be merged since it is missing unit tests. I just wanted to show any other solution.

[kazuki43zoo]

Basically, I used the SqlSession interface instead of the SqlSessionTemplate implementation.

Why? Is this changes related to this issue?
I think should be create a new issue because this change has not related with this issue.

WDYT?

[MadJlzz]

Basically, I used the SqlSession interface instead of the SqlSessionTemplate implementation.

You are totally right, about my change, it is not necessary here. I will use SqlSessionTemplate like before. Using interface instead of implementation is the key for good encapsulation and for loose coupling in the code. That's why I did it.

[MadJlzz]

@kazuki43zoo I've fixed all problems and I may have a solution. Instead of construction SqlSessionTemplate inside afterPropertiesSet, I initialize the object once if it is null.

That way, we could either use @Component and a basic constructor without having to call afterPropertiesSet.

Now, if you disagree with my point of view explained in #323, we can still abandon this PR and close the issue.

WDYT ?

[mp789991268]

Yes

[kazuki43zoo]

@MadJlzz I've merged now, Thanks for your contributing!