Avoid unnecessary object creation when parsing XML tags.

[zhangweidavid]

https://github.com/mybatis/mybatis-3/blob/master/src/main/java/org/apache/ibatis/scripting/xmltags/XMLScriptBuilder.java
These handlers are thread-safe, so they do not need to be created every time。
Using a global Map instead of local variables

#1148

[harawata]

Good point. Thank you, @zhangweidavid !

@hazendaz ,
You cleaned up this class a while ago, but it would be more efficient if we reuse the HashMap instance.
I have no strong opinion about how to instantiate it, but does this PR look OK to you?

[kazuki43zoo]

I think that this is good PR.

[zhangweidavid]

https://github.com/mybatis/mybatis-3/blob/master/src/main/java/org/apache/ibatis/reflection/factory/DefaultObjectFactory.java
I think that the method of instantiateClass in this class should be private. @harawata what do you think about this ?

[harawata]

I would remove this method and call nodeHandlerMap.get() directly.
It's redundant and the name is inaccurate.

[zhangweidavid]

Good idea.

[harawata]

I think that the method of instantiateClass in this class should be private.

Agreed!
And thank you for the additional tests. :)

[harawata]

Merged. Thanks again!